* High IO Wait with RAID 1 @ 2009-03-12 23:46 Ryan Wagoner 2009-03-13 0:48 ` Alain Williams 2009-03-13 14:48 ` John Robinson 0 siblings, 2 replies; 14+ messages in thread From: Ryan Wagoner @ 2009-03-12 23:46 UTC (permalink / raw) To: linux-raid From what I can tell the issue here lies with mdadm and/or its interaction with CentOS 5.2. Let me first go over the configuration of both systems. System 1 - CentOS 5.2 x86_64 2x Seagate 7200.9 160GB in RAID 1 2x Seagate 7200.10 320GB in RAID 1 3x Hitachi Deskstar 7K1000 1TB in RAID 5 All attached to Supermicro LSI 1068 PCI Express controller System 2 - CentOS 5.2 x86 1x Non Raid System Drive 2x Hitachi Deskstart 7K1000 1TB in RAID 1 Attached to onboard ICH controller Both systems exhibit the same issues on the RAID 1 drives. That rules out the drive brand and controller card. During any IO intensive process the IO wait will raise and the system load will climb. I've had the IO wait as high as 70% and the load at 13+ while migrating a vmdk file with vmware-vdiskmanager. You can easily recreate the issue with bonnie++. I can perform the same disk intensive operation on the RAID 5 array with almost no io wait or load. What is the deal with this? Is there something I can tweak? ^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: High IO Wait with RAID 1 2009-03-12 23:46 High IO Wait with RAID 1 Ryan Wagoner @ 2009-03-13 0:48 ` Alain Williams 2009-03-13 3:21 ` Ryan Wagoner 2009-03-13 18:42 ` David Rees 2009-03-13 14:48 ` John Robinson 1 sibling, 2 replies; 14+ messages in thread From: Alain Williams @ 2009-03-13 0:48 UTC (permalink / raw) To: Ryan Wagoner; +Cc: linux-raid On Thu, Mar 12, 2009 at 06:46:45PM -0500, Ryan Wagoner wrote: > From what I can tell the issue here lies with mdadm and/or its > interaction with CentOS 5.2. Let me first go over the configuration of > both systems. > > System 1 - CentOS 5.2 x86_64 > 2x Seagate 7200.9 160GB in RAID 1 > 2x Seagate 7200.10 320GB in RAID 1 > 3x Hitachi Deskstar 7K1000 1TB in RAID 5 > All attached to Supermicro LSI 1068 PCI Express controller > > System 2 - CentOS 5.2 x86 > 1x Non Raid System Drive > 2x Hitachi Deskstart 7K1000 1TB in RAID 1 > Attached to onboard ICH controller > > Both systems exhibit the same issues on the RAID 1 drives. That rules > out the drive brand and controller card. During any IO intensive > process the IO wait will raise and the system load will climb. I've > had the IO wait as high as 70% and the load at 13+ while migrating a > vmdk file with vmware-vdiskmanager. You can easily recreate the issue > with bonnie++. I suspect that the answer is 'no', however I am seeing problems with raid 1 on CentOS 5.2 x86_64. The system worked nicely for some 2 months, then apparently a disk died and it's mirror appeared to have problems before the first could be replaced. The motherboard & both disks have now been replaced (data saved with a bit of luck & juggling). I have been assuming hardware, but there seems little else to change... and you report long I/O waits that I saw and still see (even when I don't see the kernel error messages below). Disks have been Seagate & Samsung, but now both ST31000333AS (1TB) as raid 1. Adaptec AIC7902 Ultra320 SCSI adapter aic7902: Ultra320 Wide Channel A, SCSI Id=7, PCI-X 101-133Mhz, 512 SCBs Executing 'w' or 'cat /proc/mdstat' can take several seconds, failing sdb with mdadm and system performance becomes great again. I am seeing this sort of thing in /var/log/messages: Mar 12 09:21:58 BFPS kernel: ata2.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x2 frozen Mar 12 09:21:58 BFPS kernel: ata2.00: cmd ea/00:00:00:00:00/00:00:00:00:00/a0 tag 0 Mar 12 09:21:58 BFPS kernel: res 40/00:00:00:4f:c2/00:00:00:00:00/00 Emask 0x4 (timeout) Mar 12 09:21:58 BFPS kernel: ata2.00: status: { DRDY } Mar 12 09:22:03 BFPS kernel: ata2: port is slow to respond, please be patient (Status 0xd0) Mar 12 09:22:08 BFPS kernel: ata2: device not ready (errno=-16), forcing hardreset Mar 12 09:22:08 BFPS kernel: ata2: hard resetting link Mar 12 09:22:08 BFPS kernel: ata2: SATA link up 3.0 Gbps (SStatus 123 SControl 300) Mar 12 09:22:39 BFPS kernel: ata2.00: qc timeout (cmd 0xec) Mar 12 09:22:39 BFPS kernel: ata2.00: failed to IDENTIFY (I/O error, err_mask=0x5) Mar 12 09:22:39 BFPS kernel: ata2.00: revalidation failed (errno=-5) Mar 12 09:22:39 BFPS kernel: ata2: failed to recover some devices, retrying in 5 secs Mar 12 09:22:44 BFPS kernel: ata2: hard resetting link Mar 12 09:24:02 BFPS kernel: ata2: SATA link up 3.0 Gbps (SStatus 123 SControl 300) Mar 12 09:24:06 BFPS kernel: ata2.00: qc timeout (cmd 0xec) Mar 12 09:24:06 BFPS kernel: ata2.00: failed to IDENTIFY (I/O error, err_mask=0x5) Mar 12 09:24:06 BFPS kernel: ata2.00: revalidation failed (errno=-5) Mar 12 09:24:06 BFPS kernel: ata2: failed to recover some devices, retrying in 5 secs Mar 12 09:24:06 BFPS kernel: ata2: hard resetting link Mar 12 09:24:06 BFPS kernel: ata2: SATA link up 3.0 Gbps (SStatus 123 SControl 300) Mar 12 09:24:06 BFPS kernel: ata2.00: qc timeout (cmd 0xec) Mar 12 09:24:06 BFPS kernel: ata2.00: failed to IDENTIFY (I/O error, err_mask=0x5) Mar 12 09:24:06 BFPS kernel: ata2.00: revalidation failed (errno=-5) Mar 12 09:24:06 BFPS kernel: ata2.00: disabled Mar 12 09:24:06 BFPS kernel: ata2: port is slow to respond, please be patient (Status 0xff) Mar 12 09:24:06 BFPS kernel: ata2: device not ready (errno=-16), forcing hardreset Mar 12 09:24:06 BFPS kernel: ata2: hard resetting link Mar 12 09:24:06 BFPS kernel: ata2: SATA link up 3.0 Gbps (SStatus 123 SControl 300) Mar 12 09:24:06 BFPS kernel: ata2: EH complete Mar 12 09:24:06 BFPS kernel: sd 1:0:0:0: SCSI error: return code = 0x00040000 Mar 12 09:24:06 BFPS kernel: end_request: I/O error, dev sdb, sector 1953519821 Mar 12 09:24:06 BFPS kernel: raid1: Disk failure on sdb2, disabling device. Mar 12 09:24:06 BFPS kernel: Operation continuing on 1 devices Mar 12 09:24:06 BFPS kernel: sd 1:0:0:0: SCSI error: return code = 0x00040000 Mar 12 09:24:06 BFPS kernel: end_request: I/O error, dev sdb, sector 975018957 Mar 12 09:24:06 BFPS kernel: md: md3: sync done. Mar 12 09:24:06 BFPS kernel: sd 1:0:0:0: SCSI error: return code = 0x00040000 Mar 12 09:24:06 BFPS kernel: end_request: I/O error, dev sdb, sector 975019981 Mar 12 09:24:06 BFPS kernel: sd 1:0:0:0: SCSI error: return code = 0x00040000 Mar 12 09:24:06 BFPS kernel: end_request: I/O error, dev sdb, sector 975021005 Mar 12 09:24:06 BFPS kernel: sd 1:0:0:0: SCSI error: return code = 0x00040000 Mar 12 09:24:06 BFPS kernel: end_request: I/O error, dev sdb, sector 975022029 Mar 12 09:24:06 BFPS kernel: sd 1:0:0:0: SCSI error: return code = 0x00040000 Mar 12 09:24:06 BFPS kernel: end_request: I/O error, dev sdb, sector 975022157 Mar 12 09:24:06 BFPS kernel: RAID1 conf printout: Mar 12 09:24:06 BFPS kernel: --- wd:1 rd:2 Mar 12 09:24:06 BFPS kernel: disk 0, wo:0, o:1, dev:sda2 Mar 12 09:24:06 BFPS kernel: disk 1, wo:1, o:0, dev:sdb2 Mar 12 09:24:06 BFPS kernel: RAID1 conf printout: Mar 12 09:24:06 BFPS kernel: --- wd:1 rd:2 Mar 12 09:24:06 BFPS kernel: disk 0, wo:0, o:1, dev:sda2 Mar 12 09:28:07 BFPS smartd[3183]: Device: /dev/sdb, not capable of SMART self-check Mar 12 09:28:07 BFPS smartd[3183]: Sending warning via mail to root ... Mar 12 09:28:07 BFPS smartd[3183]: Warning via mail to root: successful Mar 12 09:28:07 BFPS smartd[3183]: Device: /dev/sdb, failed to read SMART Attribute Data Mar 12 09:28:07 BFPS smartd[3183]: Sending warning via mail to root ... Mar 12 09:28:07 BFPS smartd[3183]: Warning via mail to root: successful -- Alain Williams Linux/GNU Consultant - Mail systems, Web sites, Networking, Programmer, IT Lecturer. +44 (0) 787 668 0256 http://www.phcomp.co.uk/ Parliament Hill Computers Ltd. Registration Information: http://www.phcomp.co.uk/contact.php Past chairman of UKUUG: http://www.ukuug.org/ #include <std_disclaimer.h> ^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: High IO Wait with RAID 1 2009-03-13 0:48 ` Alain Williams @ 2009-03-13 3:21 ` Ryan Wagoner 2009-03-13 9:39 ` Robin Hill ` (2 more replies) 2009-03-13 18:42 ` David Rees 1 sibling, 3 replies; 14+ messages in thread From: Ryan Wagoner @ 2009-03-13 3:21 UTC (permalink / raw) To: Alain Williams; +Cc: linux-raid I'm glad I'm not the only one experiencing the issue. Luckily the issues on both my systems aren't as bad. I don't have any errors showing in /var/log/messages on either system. I've been trying to track down this issue for about a year now. I just recently my the connection with RAID 1 and mdadm when copying data on the second system. Unfortunately it looks like the fix is to avoid software RAID 1. I prefer software RAID over hardware RAID on my home systems for the flexibility it offers, especially since I can easily move the disks between systems in the case of hardware failure. If I can find time to migrate the VMs, which run my web sites and email to another machine, I'll reinstall the one system utilizing RAID 1 on the LSI controller. It doesn't support RAID 5 so I'm hoping I can just pass the remaining disks through. You would think that software RAID 1 would be much simpler to implement than RAID 5 performance wise. Ryan On Thu, Mar 12, 2009 at 7:48 PM, Alain Williams <addw@phcomp.co.uk> wrote: > On Thu, Mar 12, 2009 at 06:46:45PM -0500, Ryan Wagoner wrote: >> From what I can tell the issue here lies with mdadm and/or its >> interaction with CentOS 5.2. Let me first go over the configuration of >> both systems. >> >> System 1 - CentOS 5.2 x86_64 >> 2x Seagate 7200.9 160GB in RAID 1 >> 2x Seagate 7200.10 320GB in RAID 1 >> 3x Hitachi Deskstar 7K1000 1TB in RAID 5 >> All attached to Supermicro LSI 1068 PCI Express controller >> >> System 2 - CentOS 5.2 x86 >> 1x Non Raid System Drive >> 2x Hitachi Deskstart 7K1000 1TB in RAID 1 >> Attached to onboard ICH controller >> >> Both systems exhibit the same issues on the RAID 1 drives. That rules >> out the drive brand and controller card. During any IO intensive >> process the IO wait will raise and the system load will climb. I've >> had the IO wait as high as 70% and the load at 13+ while migrating a >> vmdk file with vmware-vdiskmanager. You can easily recreate the issue >> with bonnie++. > > I suspect that the answer is 'no', however I am seeing problems with raid 1 > on CentOS 5.2 x86_64. The system worked nicely for some 2 months, then apparently > a disk died and it's mirror appeared to have problems before the first could be > replaced. The motherboard & both disks have now been replaced (data saved with a bit > of luck & juggling). I have been assuming hardware, but there seems little else > to change... and you report long I/O waits that I saw and still see > (even when I don't see the kernel error messages below). > > Disks have been Seagate & Samsung, but now both ST31000333AS (1TB) as raid 1. > Adaptec AIC7902 Ultra320 SCSI adapter > aic7902: Ultra320 Wide Channel A, SCSI Id=7, PCI-X 101-133Mhz, 512 SCBs > > Executing 'w' or 'cat /proc/mdstat' can take several seconds, > failing sdb with mdadm and system performance becomes great again. > > I am seeing this sort of thing in /var/log/messages: > Mar 12 09:21:58 BFPS kernel: ata2.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x2 frozen > Mar 12 09:21:58 BFPS kernel: ata2.00: cmd ea/00:00:00:00:00/00:00:00:00:00/a0 tag 0 > Mar 12 09:21:58 BFPS kernel: res 40/00:00:00:4f:c2/00:00:00:00:00/00 Emask 0x4 (timeout) > Mar 12 09:21:58 BFPS kernel: ata2.00: status: { DRDY } > Mar 12 09:22:03 BFPS kernel: ata2: port is slow to respond, please be patient (Status 0xd0) > Mar 12 09:22:08 BFPS kernel: ata2: device not ready (errno=-16), forcing hardreset > Mar 12 09:22:08 BFPS kernel: ata2: hard resetting link > Mar 12 09:22:08 BFPS kernel: ata2: SATA link up 3.0 Gbps (SStatus 123 SControl 300) > Mar 12 09:22:39 BFPS kernel: ata2.00: qc timeout (cmd 0xec) > Mar 12 09:22:39 BFPS kernel: ata2.00: failed to IDENTIFY (I/O error, err_mask=0x5) > Mar 12 09:22:39 BFPS kernel: ata2.00: revalidation failed (errno=-5) > Mar 12 09:22:39 BFPS kernel: ata2: failed to recover some devices, retrying in 5 secs > Mar 12 09:22:44 BFPS kernel: ata2: hard resetting link > Mar 12 09:24:02 BFPS kernel: ata2: SATA link up 3.0 Gbps (SStatus 123 SControl 300) > Mar 12 09:24:06 BFPS kernel: ata2.00: qc timeout (cmd 0xec) > Mar 12 09:24:06 BFPS kernel: ata2.00: failed to IDENTIFY (I/O error, err_mask=0x5) > Mar 12 09:24:06 BFPS kernel: ata2.00: revalidation failed (errno=-5) > Mar 12 09:24:06 BFPS kernel: ata2: failed to recover some devices, retrying in 5 secs > Mar 12 09:24:06 BFPS kernel: ata2: hard resetting link > Mar 12 09:24:06 BFPS kernel: ata2: SATA link up 3.0 Gbps (SStatus 123 SControl 300) > Mar 12 09:24:06 BFPS kernel: ata2.00: qc timeout (cmd 0xec) > Mar 12 09:24:06 BFPS kernel: ata2.00: failed to IDENTIFY (I/O error, err_mask=0x5) > Mar 12 09:24:06 BFPS kernel: ata2.00: revalidation failed (errno=-5) > Mar 12 09:24:06 BFPS kernel: ata2.00: disabled > Mar 12 09:24:06 BFPS kernel: ata2: port is slow to respond, please be patient (Status 0xff) > Mar 12 09:24:06 BFPS kernel: ata2: device not ready (errno=-16), forcing hardreset > Mar 12 09:24:06 BFPS kernel: ata2: hard resetting link > Mar 12 09:24:06 BFPS kernel: ata2: SATA link up 3.0 Gbps (SStatus 123 SControl 300) > Mar 12 09:24:06 BFPS kernel: ata2: EH complete > Mar 12 09:24:06 BFPS kernel: sd 1:0:0:0: SCSI error: return code = 0x00040000 > Mar 12 09:24:06 BFPS kernel: end_request: I/O error, dev sdb, sector 1953519821 > Mar 12 09:24:06 BFPS kernel: raid1: Disk failure on sdb2, disabling device. > Mar 12 09:24:06 BFPS kernel: Operation continuing on 1 devices > Mar 12 09:24:06 BFPS kernel: sd 1:0:0:0: SCSI error: return code = 0x00040000 > Mar 12 09:24:06 BFPS kernel: end_request: I/O error, dev sdb, sector 975018957 > Mar 12 09:24:06 BFPS kernel: md: md3: sync done. > Mar 12 09:24:06 BFPS kernel: sd 1:0:0:0: SCSI error: return code = 0x00040000 > Mar 12 09:24:06 BFPS kernel: end_request: I/O error, dev sdb, sector 975019981 > Mar 12 09:24:06 BFPS kernel: sd 1:0:0:0: SCSI error: return code = 0x00040000 > Mar 12 09:24:06 BFPS kernel: end_request: I/O error, dev sdb, sector 975021005 > Mar 12 09:24:06 BFPS kernel: sd 1:0:0:0: SCSI error: return code = 0x00040000 > Mar 12 09:24:06 BFPS kernel: end_request: I/O error, dev sdb, sector 975022029 > Mar 12 09:24:06 BFPS kernel: sd 1:0:0:0: SCSI error: return code = 0x00040000 > Mar 12 09:24:06 BFPS kernel: end_request: I/O error, dev sdb, sector 975022157 > Mar 12 09:24:06 BFPS kernel: RAID1 conf printout: > Mar 12 09:24:06 BFPS kernel: --- wd:1 rd:2 > Mar 12 09:24:06 BFPS kernel: disk 0, wo:0, o:1, dev:sda2 > Mar 12 09:24:06 BFPS kernel: disk 1, wo:1, o:0, dev:sdb2 > Mar 12 09:24:06 BFPS kernel: RAID1 conf printout: > Mar 12 09:24:06 BFPS kernel: --- wd:1 rd:2 > Mar 12 09:24:06 BFPS kernel: disk 0, wo:0, o:1, dev:sda2 > > Mar 12 09:28:07 BFPS smartd[3183]: Device: /dev/sdb, not capable of SMART self-check > Mar 12 09:28:07 BFPS smartd[3183]: Sending warning via mail to root ... > Mar 12 09:28:07 BFPS smartd[3183]: Warning via mail to root: successful > Mar 12 09:28:07 BFPS smartd[3183]: Device: /dev/sdb, failed to read SMART Attribute Data > Mar 12 09:28:07 BFPS smartd[3183]: Sending warning via mail to root ... > Mar 12 09:28:07 BFPS smartd[3183]: Warning via mail to root: successful > > > > -- > Alain Williams > Linux/GNU Consultant - Mail systems, Web sites, Networking, Programmer, IT Lecturer. > +44 (0) 787 668 0256 http://www.phcomp.co.uk/ > Parliament Hill Computers Ltd. Registration Information: http://www.phcomp.co.uk/contact.php > Past chairman of UKUUG: http://www.ukuug.org/ > #include <std_disclaimer.h> > -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html ^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: High IO Wait with RAID 1 2009-03-13 3:21 ` Ryan Wagoner @ 2009-03-13 9:39 ` Robin Hill 2009-03-13 10:17 ` Alain Williams 2009-03-13 16:22 ` Bill Davidsen 2 siblings, 0 replies; 14+ messages in thread From: Robin Hill @ 2009-03-13 9:39 UTC (permalink / raw) To: linux-raid [-- Attachment #1: Type: text/plain, Size: 1626 bytes --] On Thu Mar 12, 2009 at 10:21:28PM -0500, Ryan Wagoner wrote: > I'm glad I'm not the only one experiencing the issue. Luckily the > issues on both my systems aren't as bad. I don't have any errors > showing in /var/log/messages on either system. I've been trying to > track down this issue for about a year now. I just recently my the > connection with RAID 1 and mdadm when copying data on the second > system. > > Unfortunately it looks like the fix is to avoid software RAID 1. I > prefer software RAID over hardware RAID on my home systems for the > flexibility it offers, especially since I can easily move the disks > between systems in the case of hardware failure. > > If I can find time to migrate the VMs, which run my web sites and > email to another machine, I'll reinstall the one system utilizing RAID > 1 on the LSI controller. It doesn't support RAID 5 so I'm hoping I can > just pass the remaining disks through. > You could also try using software RAID 10 or RAID 5 on the two drives. Both of these will be effectively the same as a RAID 1 (ISTR you can actually just update the metadata to convert from a RAID 1 to a RAID 5) but will use a different code path so should eliminate the issue you're seeing. A 2 drive RAID 10 with far layout will also give some read performance improvements (at the cost of slightly slower writes). Cheers, Robin -- ___ ( ' } | Robin Hill <robin@robinhill.me.uk> | / / ) | Little Jim says .... | // !! | "He fallen in de water !!" | [-- Attachment #2: Type: application/pgp-signature, Size: 197 bytes --] ^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: High IO Wait with RAID 1 2009-03-13 3:21 ` Ryan Wagoner 2009-03-13 9:39 ` Robin Hill @ 2009-03-13 10:17 ` Alain Williams [not found] ` <7d86ddb90903130519p4268dc33vc8ad42b53aefa2e2@mail.gmail.com> 2009-03-13 16:22 ` Bill Davidsen 2 siblings, 1 reply; 14+ messages in thread From: Alain Williams @ 2009-03-13 10:17 UTC (permalink / raw) To: Ryan Wagoner; +Cc: linux-raid On Thu, Mar 12, 2009 at 10:21:28PM -0500, Ryan Wagoner wrote: > I'm glad I'm not the only one experiencing the issue. Luckily the > issues on both my systems aren't as bad. I don't have any errors > showing in /var/log/messages on either system. I've been trying to > track down this issue for about a year now. I just recently my the > connection with RAID 1 and mdadm when copying data on the second > system. Did you have the problem straight from install, or perhaps when a new kernel started being used ? My system worked well for some months, there was no kernel update and it started to go wrong a couple of weeks ago. I also see errors when I run 'badblocks' -- which makes it smell of a hardware issue, but the disks were tested, on return, by the hardware supplier and they did not find any problem with them. Given that you are not seeing anything in /var/log/messages make me think that I do have some other problem -- perhaps in addition to what you have. -- Alain Williams Linux/GNU Consultant - Mail systems, Web sites, Networking, Programmer, IT Lecturer. +44 (0) 787 668 0256 http://www.phcomp.co.uk/ Parliament Hill Computers Ltd. Registration Information: http://www.phcomp.co.uk/contact.php Past chairman of UKUUG: http://www.ukuug.org/ #include <std_disclaimer.h> ^ permalink raw reply [flat|nested] 14+ messages in thread
[parent not found: <7d86ddb90903130519p4268dc33vc8ad42b53aefa2e2@mail.gmail.com>]
* Fwd: High IO Wait with RAID 1 [not found] ` <7d86ddb90903130519p4268dc33vc8ad42b53aefa2e2@mail.gmail.com> @ 2009-03-13 12:21 ` Ryan Wagoner 0 siblings, 0 replies; 14+ messages in thread From: Ryan Wagoner @ 2009-03-13 12:21 UTC (permalink / raw) To: linux-raid I tried rolling back the kernal and have the same issue. Here is an example of the dstat output when writing with bonnie++ on RAID 1. As soon as the write buffer fills up the wait climbs as it is waiting to write to the disk. The output looks the same on both systems. usr sys idl wai hiq siq| read writ| recv send| in out | int csw 0 0 100 0 0 0| 0 0 | 586B 1682B| 0 0 |1015 110 0 0 100 0 0 0| 0 0 | 64B 412B| 0 0 |1022 96 4 1 96 1 0 0| 40k 0 | 238B 664B| 0 0 |1011 124 43 6 50 1 0 0|4096B 0 | 375B 428B| 0 0 |1026 90 43 7 50 0 0 0| 0 0 | 64B 412B| 0 0 |1005 60 43 8 50 0 0 0| 0 0 | 64B 412B| 0 0 |1023 91 43 6 50 0 0 0|4096B 0 | 64B 412B| 0 0 |1006 77 40 14 44 0 0 1| 0 62M| 158B 396B| 0 0 |1194 160 40 10 0 46 0 3| 0 145M| 158B 522B| 0 0 |1297 128 38 8 0 52 0 3|4096B 127M| 64B 412B| 0 0 |1276 147 41 9 1 48 0 3|4096B 120M| 174B 366B| 0 0 |1252 129 43 8 3 45 0 0| 0 16k| 158B 412B| 0 0 |1012 113 40 16 6 36 0 1|4096B 41M| 64B 318B| 0 0 |1142 188 42 11 0 45 0 2| 0 130M| 64B 675B| 0 0 |1327 276 43 9 0 44 0 4| 0 138M| 64B 412B| 0 0 |1280 130 34 9 16 38 0 2|4096B 107M| 64B 412B| 0 0 |1229 120 44 9 4 44 0 0| 0 8192B| 64B 412B| 0 0 |1024 175 41 17 0 41 0 0| 0 33M| 192B 366B| 0 0 |1096 193 37 9 1 51 0 3|4096B 126M| 64B 428B| 0 0 |1288 173 44 8 0 44 0 3| 0 142M| 64B 412B| 0 0 |1289 164 Here is the dstat output with the same bonnie command on the RAID 5 volume. This machine has two VMware guests running so the system wasn't idle when grabbing the output. usr sys idl wai hiq siq| read writ| recv send| in out | int csw 1 14 83 2 0 0| 120k 537k| 0 0 | 0 0.2 |3084 10k 18 11 68 1 0 0| 40k 8192B|9180B 1192B| 0 0 |3074 12k 36 18 43 2 0 0| 272k 24M| 123k 4865B| 0 0 |3858 14k 30 26 42 1 1 2| 808k 67M| 21k 1418B| 0 0 |5253 18k 39 19 43 0 0 0|4096B 0 |4600B 692B| 0 0 |3079 11k 36 19 29 17 0 0| 116k 1104k|3024B 2464B| 0 0 |3221 10k 40 17 14 30 0 1| 136k 400k| 86k 5828B| 0 0 |3189 10k 37 21 17 23 0 0| 380k 35M| 30k 1708B| 0 0 |4223 16k 30 29 37 2 2 2|1160k 115M| 390B 550B| 0 0 |6647 24k 31 29 37 1 1 2|1112k 127M| 664B 314B| 0 0 |6745 24k 33 26 28 11 0 1| 728k 71M|3074B 526B| 0 0 |4608 16k 37 24 2 37 0 0| 0 16k|1616B 14k| 0 0 |3086 10k 34 21 11 33 1 1| 388k 33M| 26k 1280B| 0 0 |3939 13k 30 32 36 1 1 1|1304k 111M| 60B 420B| 0 0 |5083 19k 31 35 30 2 1 2|1296k 125M| 19k 2051B| 0 0 |5987 20k 38 22 19 22 0 1| 692k 28M|3084B 2480B| 0 0 |3744 11k 41 17 38 3 0 0| 736k 2184k| 120B 298B| 0 0 |3785 11k 34 30 21 14 0 0| 360k 35M| 48k 2862B| 0 0 |4178 12k 37 26 35 1 1 1|1056k 136M| 13k 1394B| 0 0 |4331 11k 34 28 33 2 0 1|1228k 134M| 30k 1658B| 0 0 |4132 11k 36 21 28 14 0 0| 332k 23M| 151k 5798B| 0 0 |3368 9166 37 18 18 28 0 0| 16k 88k| 13k 990B| 0 0 |3092 8403 38 23 23 16 1 0| 316k 39M| 30k 1920B| 0 0 |3635 9723 32 33 33 2 0 1|1180k 132M| 295B 404B| 0 0 |3907 9935 31 31 35 2 1 1|1120k 123M| 43k 2424B| 0 0 |4746 14k 32 29 37 2 1 1|1380k 71M|3084B 2440B| 0 0 |5341 19k 37 24 36 1 0 0| 700k 53M| 459B 496B| 0 0 |4402 20k 35 20 29 14 1 1|1808k 61M|4596B 500B| 0 0 |5551 19k 30 30 35 2 1 3|1076k 107M| 246B 620B| 0 0 |6769 24k 36 25 30 7 1 2|1088k 66M| 165k 10k| 0 0 |5093 17k On Fri, Mar 13, 2009 at 5:17 AM, Alain Williams <addw@phcomp.co.uk> wrote: > On Thu, Mar 12, 2009 at 10:21:28PM -0500, Ryan Wagoner wrote: >> I'm glad I'm not the only one experiencing the issue. Luckily the >> issues on both my systems aren't as bad. I don't have any errors >> showing in /var/log/messages on either system. I've been trying to >> track down this issue for about a year now. I just recently my the >> connection with RAID 1 and mdadm when copying data on the second >> system. > > Did you have the problem straight from install, or perhaps when a new > kernel started being used ? > > My system worked well for some months, there was no kernel update and > it started to go wrong a couple of weeks ago. I also see errors > when I run 'badblocks' -- which makes it smell of a hardware issue, > but the disks were tested, on return, by the hardware supplier and > they did not find any problem with them. > > Given that you are not seeing anything in /var/log/messages make me > think that I do have some other problem -- perhaps in addition to > what you have. > > -- > Alain Williams > Linux/GNU Consultant - Mail systems, Web sites, Networking, Programmer, IT Lecturer. > +44 (0) 787 668 0256 http://www.phcomp.co.uk/ > Parliament Hill Computers Ltd. Registration Information: http://www.phcomp.co.uk/contact.php > Past chairman of UKUUG: http://www.ukuug.org/ > #include <std_disclaimer.h> > -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html ^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: High IO Wait with RAID 1 2009-03-13 3:21 ` Ryan Wagoner 2009-03-13 9:39 ` Robin Hill 2009-03-13 10:17 ` Alain Williams @ 2009-03-13 16:22 ` Bill Davidsen 2009-03-13 17:42 ` Ryan Wagoner 2 siblings, 1 reply; 14+ messages in thread From: Bill Davidsen @ 2009-03-13 16:22 UTC (permalink / raw) To: Ryan Wagoner; +Cc: Alain Williams, linux-raid Ryan Wagoner wrote: > I'm glad I'm not the only one experiencing the issue. Luckily the > issues on both my systems aren't as bad. I don't have any errors > showing in /var/log/messages on either system. I've been trying to > track down this issue for about a year now. I just recently my the > connection with RAID 1 and mdadm when copying data on the second > system. > > Unfortunately it looks like the fix is to avoid software RAID 1. I > prefer software RAID over hardware RAID on my home systems for the > flexibility it offers, especially since I can easily move the disks > between systems in the case of hardware failure. > > If I can find time to migrate the VMs, which run my web sites and > email to another machine, I'll reinstall the one system utilizing RAID > 1 on the LSI controller. It doesn't support RAID 5 so I'm hoping I can > just pass the remaining disks through. > > You would think that software RAID 1 would be much simpler to > implement than RAID 5 performance wise. > > Ryan > > On Thu, Mar 12, 2009 at 7:48 PM, Alain Williams <addw@phcomp.co.uk> wrote: > >> On Thu, Mar 12, 2009 at 06:46:45PM -0500, Ryan Wagoner wrote: >> >>> From what I can tell the issue here lies with mdadm and/or its >>> interaction with CentOS 5.2. Let me first go over the configuration of >>> both systems. >>> >>> System 1 - CentOS 5.2 x86_64 >>> 2x Seagate 7200.9 160GB in RAID 1 >>> 2x Seagate 7200.10 320GB in RAID 1 >>> 3x Hitachi Deskstar 7K1000 1TB in RAID 5 >>> All attached to Supermicro LSI 1068 PCI Express controller >>> >>> System 2 - CentOS 5.2 x86 >>> 1x Non Raid System Drive >>> 2x Hitachi Deskstart 7K1000 1TB in RAID 1 >>> Attached to onboard ICH controller >>> >>> Both systems exhibit the same issues on the RAID 1 drives. That rules >>> out the drive brand and controller card. During any IO intensive >>> process the IO wait will raise and the system load will climb. I've >>> had the IO wait as high as 70% and the load at 13+ while migrating a >>> vmdk file with vmware-vdiskmanager. You can easily recreate the issue >>> with bonnie++. >>> >> I suspect that the answer is 'no', however I am seeing problems with raid 1 >> on CentOS 5.2 x86_64. The system worked nicely for some 2 months, then apparently >> a disk died and it's mirror appeared to have problems before the first could be >> replaced. The motherboard & both disks have now been replaced (data saved with a bit >> of luck & juggling). I have been assuming hardware, but there seems little else >> to change... and you report long I/O waits that I saw and still see >> (even when I don't see the kernel error messages below). >> >> Disks have been Seagate & Samsung, but now both ST31000333AS (1TB) as raid 1. >> Adaptec AIC7902 Ultra320 SCSI adapter >> aic7902: Ultra320 Wide Channel A, SCSI Id=7, PCI-X 101-133Mhz, 512 SCBs >> >> Executing 'w' or 'cat /proc/mdstat' can take several seconds, >> failing sdb with mdadm and system performance becomes great again. >> >> I am seeing this sort of thing in /var/log/messages: >> Mar 12 09:21:58 BFPS kernel: ata2.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x2 frozen >> Mar 12 09:21:58 BFPS kernel: ata2.00: cmd ea/00:00:00:00:00/00:00:00:00:00/a0 tag 0 >> Mar 12 09:21:58 BFPS kernel: res 40/00:00:00:4f:c2/00:00:00:00:00/00 Emask 0x4 (timeout) >> Mar 12 09:21:58 BFPS kernel: ata2.00: status: { DRDY } >> Mar 12 09:22:03 BFPS kernel: ata2: port is slow to respond, please be patient (Status 0xd0) >> Mar 12 09:22:08 BFPS kernel: ata2: device not ready (errno=-16), forcing hardreset >> Mar 12 09:22:08 BFPS kernel: ata2: hard resetting link >> Mar 12 09:22:08 BFPS kernel: ata2: SATA link up 3.0 Gbps (SStatus 123 SControl 300) >> Mar 12 09:22:39 BFPS kernel: ata2.00: qc timeout (cmd 0xec) >> Mar 12 09:22:39 BFPS kernel: ata2.00: failed to IDENTIFY (I/O error, err_mask=0x5) >> Mar 12 09:22:39 BFPS kernel: ata2.00: revalidation failed (errno=-5) >> Mar 12 09:22:39 BFPS kernel: ata2: failed to recover some devices, retrying in 5 secs >> Mar 12 09:22:44 BFPS kernel: ata2: hard resetting link >> Mar 12 09:24:02 BFPS kernel: ata2: SATA link up 3.0 Gbps (SStatus 123 SControl 300) >> Mar 12 09:24:06 BFPS kernel: ata2.00: qc timeout (cmd 0xec) >> Mar 12 09:24:06 BFPS kernel: ata2.00: failed to IDENTIFY (I/O error, err_mask=0x5) >> Mar 12 09:24:06 BFPS kernel: ata2.00: revalidation failed (errno=-5) >> Mar 12 09:24:06 BFPS kernel: ata2: failed to recover some devices, retrying in 5 secs >> Mar 12 09:24:06 BFPS kernel: ata2: hard resetting link >> Mar 12 09:24:06 BFPS kernel: ata2: SATA link up 3.0 Gbps (SStatus 123 SControl 300) >> Mar 12 09:24:06 BFPS kernel: ata2.00: qc timeout (cmd 0xec) >> Mar 12 09:24:06 BFPS kernel: ata2.00: failed to IDENTIFY (I/O error, err_mask=0x5) >> Mar 12 09:24:06 BFPS kernel: ata2.00: revalidation failed (errno=-5) >> Mar 12 09:24:06 BFPS kernel: ata2.00: disabled >> Mar 12 09:24:06 BFPS kernel: ata2: port is slow to respond, please be patient (Status 0xff) >> Mar 12 09:24:06 BFPS kernel: ata2: device not ready (errno=-16), forcing hardreset >> Mar 12 09:24:06 BFPS kernel: ata2: hard resetting link >> Mar 12 09:24:06 BFPS kernel: ata2: SATA link up 3.0 Gbps (SStatus 123 SControl 300) >> Mar 12 09:24:06 BFPS kernel: ata2: EH complete >> Mar 12 09:24:06 BFPS kernel: sd 1:0:0:0: SCSI error: return code = 0x00040000 >> Mar 12 09:24:06 BFPS kernel: end_request: I/O error, dev sdb, sector 1953519821 >> Mar 12 09:24:06 BFPS kernel: raid1: Disk failure on sdb2, disabling device. >> Mar 12 09:24:06 BFPS kernel: Operation continuing on 1 devices >> Mar 12 09:24:06 BFPS kernel: sd 1:0:0:0: SCSI error: return code = 0x00040000 >> Mar 12 09:24:06 BFPS kernel: end_request: I/O error, dev sdb, sector 975018957 >> Mar 12 09:24:06 BFPS kernel: md: md3: sync done. >> Mar 12 09:24:06 BFPS kernel: sd 1:0:0:0: SCSI error: return code = 0x00040000 >> Mar 12 09:24:06 BFPS kernel: end_request: I/O error, dev sdb, sector 975019981 >> Mar 12 09:24:06 BFPS kernel: sd 1:0:0:0: SCSI error: return code = 0x00040000 >> Mar 12 09:24:06 BFPS kernel: end_request: I/O error, dev sdb, sector 975021005 >> Mar 12 09:24:06 BFPS kernel: sd 1:0:0:0: SCSI error: return code = 0x00040000 >> Mar 12 09:24:06 BFPS kernel: end_request: I/O error, dev sdb, sector 975022029 >> Mar 12 09:24:06 BFPS kernel: sd 1:0:0:0: SCSI error: return code = 0x00040000 >> Mar 12 09:24:06 BFPS kernel: end_request: I/O error, dev sdb, sector 975022157 >> Mar 12 09:24:06 BFPS kernel: RAID1 conf printout: >> Mar 12 09:24:06 BFPS kernel: --- wd:1 rd:2 >> Mar 12 09:24:06 BFPS kernel: disk 0, wo:0, o:1, dev:sda2 >> Mar 12 09:24:06 BFPS kernel: disk 1, wo:1, o:0, dev:sdb2 >> Mar 12 09:24:06 BFPS kernel: RAID1 conf printout: >> Mar 12 09:24:06 BFPS kernel: --- wd:1 rd:2 >> Mar 12 09:24:06 BFPS kernel: disk 0, wo:0, o:1, dev:sda2 >> >> Mar 12 09:28:07 BFPS smartd[3183]: Device: /dev/sdb, not capable of SMART self-check >> Mar 12 09:28:07 BFPS smartd[3183]: Sending warning via mail to root ... >> Mar 12 09:28:07 BFPS smartd[3183]: Warning via mail to root: successful >> Mar 12 09:28:07 BFPS smartd[3183]: Device: /dev/sdb, failed to read SMART Attribute Data >> Mar 12 09:28:07 BFPS smartd[3183]: Sending warning via mail to root ... >> Mar 12 09:28:07 BFPS smartd[3183]: Warning via mail to root: successful >> Part of the issue with software RAID is that when you do two writes, be it mirrors or CRC, you actually have to push the data over the system bus to the controller. With hardware RAID you push it to the controller, freeing the bus. "But wait, there's more" because the controller on a motherboard may not have enough cache to hold the i/o, may not optimize the access, etc, etc. And worst case it may write one drive then the other (serial access) instead of writing both at once. So performance may not be a bit better with the motherboard controller, and even an independent controller may not help much under load, since the limits here are the memory for cache (software has more) and the smartness of the write decisions (software is usually at least as good). Going to hardware RAID buys only one thing in my experience, and that is it works at boot time, before the kernel gets into memory. The other issue is that hardware RAID is per-disk, while software can allow selection of multiple RAID types by partition, allowing arrays to match use when that's appropriate. -- Bill Davidsen <davidsen@tmr.com> "Woe unto the statesman who makes war without a reason that will still be valid when the war is over..." Otto von Bismark ^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: High IO Wait with RAID 1 2009-03-13 16:22 ` Bill Davidsen @ 2009-03-13 17:42 ` Ryan Wagoner 2009-03-13 18:37 ` David Rees 0 siblings, 1 reply; 14+ messages in thread From: Ryan Wagoner @ 2009-03-13 17:42 UTC (permalink / raw) To: Bill Davidsen; +Cc: Alain Williams, linux-raid Yeah I understand the basics to RAID and the effect cache has on performance. It just seems that RAID 1 should offer better write performance than a 3 drive RAID 5 array. However I haven't run the numbers so I could be wrong. It could be just that I expect too much from RAID 1. I'm debating about reloading the box with RAID 10 across 160GB of the 4 drives (160GB and 320GB) and a mirror on the remaining space. In theory this should gain me write performance. Thanks, Ryan On Fri, Mar 13, 2009 at 11:22 AM, Bill Davidsen <davidsen@tmr.com> wrote: > Ryan Wagoner wrote: >> >> I'm glad I'm not the only one experiencing the issue. Luckily the >> issues on both my systems aren't as bad. I don't have any errors >> showing in /var/log/messages on either system. I've been trying to >> track down this issue for about a year now. I just recently my the >> connection with RAID 1 and mdadm when copying data on the second >> system. >> >> Unfortunately it looks like the fix is to avoid software RAID 1. I >> prefer software RAID over hardware RAID on my home systems for the >> flexibility it offers, especially since I can easily move the disks >> between systems in the case of hardware failure. >> >> If I can find time to migrate the VMs, which run my web sites and >> email to another machine, I'll reinstall the one system utilizing RAID >> 1 on the LSI controller. It doesn't support RAID 5 so I'm hoping I can >> just pass the remaining disks through. >> >> You would think that software RAID 1 would be much simpler to >> implement than RAID 5 performance wise. >> >> Ryan >> >> On Thu, Mar 12, 2009 at 7:48 PM, Alain Williams <addw@phcomp.co.uk> wrote: >> >>> >>> On Thu, Mar 12, 2009 at 06:46:45PM -0500, Ryan Wagoner wrote: >>> >>>> >>>> From what I can tell the issue here lies with mdadm and/or its >>>> interaction with CentOS 5.2. Let me first go over the configuration of >>>> both systems. >>>> >>>> System 1 - CentOS 5.2 x86_64 >>>> 2x Seagate 7200.9 160GB in RAID 1 >>>> 2x Seagate 7200.10 320GB in RAID 1 >>>> 3x Hitachi Deskstar 7K1000 1TB in RAID 5 >>>> All attached to Supermicro LSI 1068 PCI Express controller >>>> >>>> System 2 - CentOS 5.2 x86 >>>> 1x Non Raid System Drive >>>> 2x Hitachi Deskstart 7K1000 1TB in RAID 1 >>>> Attached to onboard ICH controller >>>> >>>> Both systems exhibit the same issues on the RAID 1 drives. That rules >>>> out the drive brand and controller card. During any IO intensive >>>> process the IO wait will raise and the system load will climb. I've >>>> had the IO wait as high as 70% and the load at 13+ while migrating a >>>> vmdk file with vmware-vdiskmanager. You can easily recreate the issue >>>> with bonnie++. >>>> >>> >>> I suspect that the answer is 'no', however I am seeing problems with raid >>> 1 >>> on CentOS 5.2 x86_64. The system worked nicely for some 2 months, then >>> apparently >>> a disk died and it's mirror appeared to have problems before the first >>> could be >>> replaced. The motherboard & both disks have now been replaced (data saved >>> with a bit >>> of luck & juggling). I have been assuming hardware, but there seems >>> little else >>> to change... and you report long I/O waits that I saw and still see >>> (even when I don't see the kernel error messages below). >>> >>> Disks have been Seagate & Samsung, but now both ST31000333AS (1TB) as >>> raid 1. >>> Adaptec AIC7902 Ultra320 SCSI adapter >>> aic7902: Ultra320 Wide Channel A, SCSI Id=7, PCI-X 101-133Mhz, 512 SCBs >>> >>> Executing 'w' or 'cat /proc/mdstat' can take several seconds, >>> failing sdb with mdadm and system performance becomes great again. >>> >>> I am seeing this sort of thing in /var/log/messages: >>> Mar 12 09:21:58 BFPS kernel: ata2.00: exception Emask 0x0 SAct 0x0 SErr >>> 0x0 action 0x2 frozen >>> Mar 12 09:21:58 BFPS kernel: ata2.00: cmd >>> ea/00:00:00:00:00/00:00:00:00:00/a0 tag 0 >>> Mar 12 09:21:58 BFPS kernel: res >>> 40/00:00:00:4f:c2/00:00:00:00:00/00 Emask 0x4 (timeout) >>> Mar 12 09:21:58 BFPS kernel: ata2.00: status: { DRDY } >>> Mar 12 09:22:03 BFPS kernel: ata2: port is slow to respond, please be >>> patient (Status 0xd0) >>> Mar 12 09:22:08 BFPS kernel: ata2: device not ready (errno=-16), forcing >>> hardreset >>> Mar 12 09:22:08 BFPS kernel: ata2: hard resetting link >>> Mar 12 09:22:08 BFPS kernel: ata2: SATA link up 3.0 Gbps (SStatus 123 >>> SControl 300) >>> Mar 12 09:22:39 BFPS kernel: ata2.00: qc timeout (cmd 0xec) >>> Mar 12 09:22:39 BFPS kernel: ata2.00: failed to IDENTIFY (I/O error, >>> err_mask=0x5) >>> Mar 12 09:22:39 BFPS kernel: ata2.00: revalidation failed (errno=-5) >>> Mar 12 09:22:39 BFPS kernel: ata2: failed to recover some devices, >>> retrying in 5 secs >>> Mar 12 09:22:44 BFPS kernel: ata2: hard resetting link >>> Mar 12 09:24:02 BFPS kernel: ata2: SATA link up 3.0 Gbps (SStatus 123 >>> SControl 300) >>> Mar 12 09:24:06 BFPS kernel: ata2.00: qc timeout (cmd 0xec) >>> Mar 12 09:24:06 BFPS kernel: ata2.00: failed to IDENTIFY (I/O error, >>> err_mask=0x5) >>> Mar 12 09:24:06 BFPS kernel: ata2.00: revalidation failed (errno=-5) >>> Mar 12 09:24:06 BFPS kernel: ata2: failed to recover some devices, >>> retrying in 5 secs >>> Mar 12 09:24:06 BFPS kernel: ata2: hard resetting link >>> Mar 12 09:24:06 BFPS kernel: ata2: SATA link up 3.0 Gbps (SStatus 123 >>> SControl 300) >>> Mar 12 09:24:06 BFPS kernel: ata2.00: qc timeout (cmd 0xec) >>> Mar 12 09:24:06 BFPS kernel: ata2.00: failed to IDENTIFY (I/O error, >>> err_mask=0x5) >>> Mar 12 09:24:06 BFPS kernel: ata2.00: revalidation failed (errno=-5) >>> Mar 12 09:24:06 BFPS kernel: ata2.00: disabled >>> Mar 12 09:24:06 BFPS kernel: ata2: port is slow to respond, please be >>> patient (Status 0xff) >>> Mar 12 09:24:06 BFPS kernel: ata2: device not ready (errno=-16), forcing >>> hardreset >>> Mar 12 09:24:06 BFPS kernel: ata2: hard resetting link >>> Mar 12 09:24:06 BFPS kernel: ata2: SATA link up 3.0 Gbps (SStatus 123 >>> SControl 300) >>> Mar 12 09:24:06 BFPS kernel: ata2: EH complete >>> Mar 12 09:24:06 BFPS kernel: sd 1:0:0:0: SCSI error: return code = >>> 0x00040000 >>> Mar 12 09:24:06 BFPS kernel: end_request: I/O error, dev sdb, sector >>> 1953519821 >>> Mar 12 09:24:06 BFPS kernel: raid1: Disk failure on sdb2, disabling >>> device. >>> Mar 12 09:24:06 BFPS kernel: Operation continuing on 1 devices >>> Mar 12 09:24:06 BFPS kernel: sd 1:0:0:0: SCSI error: return code = >>> 0x00040000 >>> Mar 12 09:24:06 BFPS kernel: end_request: I/O error, dev sdb, sector >>> 975018957 >>> Mar 12 09:24:06 BFPS kernel: md: md3: sync done. >>> Mar 12 09:24:06 BFPS kernel: sd 1:0:0:0: SCSI error: return code = >>> 0x00040000 >>> Mar 12 09:24:06 BFPS kernel: end_request: I/O error, dev sdb, sector >>> 975019981 >>> Mar 12 09:24:06 BFPS kernel: sd 1:0:0:0: SCSI error: return code = >>> 0x00040000 >>> Mar 12 09:24:06 BFPS kernel: end_request: I/O error, dev sdb, sector >>> 975021005 >>> Mar 12 09:24:06 BFPS kernel: sd 1:0:0:0: SCSI error: return code = >>> 0x00040000 >>> Mar 12 09:24:06 BFPS kernel: end_request: I/O error, dev sdb, sector >>> 975022029 >>> Mar 12 09:24:06 BFPS kernel: sd 1:0:0:0: SCSI error: return code = >>> 0x00040000 >>> Mar 12 09:24:06 BFPS kernel: end_request: I/O error, dev sdb, sector >>> 975022157 >>> Mar 12 09:24:06 BFPS kernel: RAID1 conf printout: >>> Mar 12 09:24:06 BFPS kernel: --- wd:1 rd:2 >>> Mar 12 09:24:06 BFPS kernel: disk 0, wo:0, o:1, dev:sda2 >>> Mar 12 09:24:06 BFPS kernel: disk 1, wo:1, o:0, dev:sdb2 >>> Mar 12 09:24:06 BFPS kernel: RAID1 conf printout: >>> Mar 12 09:24:06 BFPS kernel: --- wd:1 rd:2 >>> Mar 12 09:24:06 BFPS kernel: disk 0, wo:0, o:1, dev:sda2 >>> >>> Mar 12 09:28:07 BFPS smartd[3183]: Device: /dev/sdb, not capable of SMART >>> self-check >>> Mar 12 09:28:07 BFPS smartd[3183]: Sending warning via mail to root ... >>> Mar 12 09:28:07 BFPS smartd[3183]: Warning via mail to root: successful >>> Mar 12 09:28:07 BFPS smartd[3183]: Device: /dev/sdb, failed to read SMART >>> Attribute Data >>> Mar 12 09:28:07 BFPS smartd[3183]: Sending warning via mail to root ... >>> Mar 12 09:28:07 BFPS smartd[3183]: Warning via mail to root: successful >>> > > Part of the issue with software RAID is that when you do two writes, be it > mirrors or CRC, you actually have to push the data over the system bus to > the controller. With hardware RAID you push it to the controller, freeing > the bus. > > "But wait, there's more" because the controller on a motherboard may not > have enough cache to hold the i/o, may not optimize the access, etc, etc. > And worst case it may write one drive then the other (serial access) instead > of writing both at once. So performance may not be a bit better with the > motherboard controller, and even an independent controller may not help much > under load, since the limits here are the memory for cache (software has > more) and the smartness of the write decisions (software is usually at least > as good). > > Going to hardware RAID buys only one thing in my experience, and that is it > works at boot time, before the kernel gets into memory. > > The other issue is that hardware RAID is per-disk, while software can allow > selection of multiple RAID types by partition, allowing arrays to match use > when that's appropriate. > > -- > Bill Davidsen <davidsen@tmr.com> > "Woe unto the statesman who makes war without a reason that will still > be valid when the war is over..." Otto von Bismark > > -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html ^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: High IO Wait with RAID 1 2009-03-13 17:42 ` Ryan Wagoner @ 2009-03-13 18:37 ` David Rees 0 siblings, 0 replies; 14+ messages in thread From: David Rees @ 2009-03-13 18:37 UTC (permalink / raw) To: Ryan Wagoner; +Cc: Bill Davidsen, Alain Williams, linux-raid On Fri, Mar 13, 2009 at 10:42 AM, Ryan Wagoner <rswagoner@gmail.com> wrote: > Yeah I understand the basics to RAID and the effect cache has on > performance. It just seems that RAID 1 should offer better write > performance than a 3 drive RAID 5 array. However I haven't run the > numbers so I could be wrong. If we just look at best case scenario write throughput where N is the number of disks in the array: RAID1 = 1 RAID5 = N-1 So for your case, your RAID5 array should be able to write up to twice as fast as your RAID1 array. This could be enough to explain the difference in load. Where RAID5 writes slow down significantly is if you are writing chunks smaller than the stripe size and the affected stripe isn't in cache and a read has to be performed before the write to recalculate the parity. But for your use case of transferring large VM images, this is unlikely to be the case. In otherwords, what you are experiencing (high IO wait writing to the RAID1 arrays) is to be expected. From the stats you posted earlier, it looks like you are maxing out the write speed of the RAID1 arrays - thus you end up with high IO wait times. > It could be just that I expect too much from RAID 1. I'm debating > about reloading the box with RAID 10 across 160GB of the 4 drives > (160GB and 320GB) and a mirror on the remaining space. In theory this > should gain me write performance. Yes, a RAID10 with 4 disks will get you up to twice the write performance and up to 4 times the read performance without the drawback of small writes losing performance due to parity reads. -Dave ^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: High IO Wait with RAID 1 2009-03-13 0:48 ` Alain Williams 2009-03-13 3:21 ` Ryan Wagoner @ 2009-03-13 18:42 ` David Rees 1 sibling, 0 replies; 14+ messages in thread From: David Rees @ 2009-03-13 18:42 UTC (permalink / raw) To: Alain Williams; +Cc: Ryan Wagoner, linux-raid On Thu, Mar 12, 2009 at 5:48 PM, Alain Williams <addw@phcomp.co.uk> wrote: > I suspect that the answer is 'no', however I am seeing problems with raid 1 > on CentOS 5.2 x86_64. The system worked nicely for some 2 months, then apparently > a disk died and it's mirror appeared to have problems before the first could be > replaced. The motherboard & both disks have now been replaced (data saved with a bit > of luck & juggling). I have been assuming hardware, but there seems little else > to change... and you report long I/O waits that I saw and still see > (even when I don't see the kernel error messages below). > > Disks have been Seagate & Samsung, but now both ST31000333AS (1TB) as raid 1. > Adaptec AIC7902 Ultra320 SCSI adapter > aic7902: Ultra320 Wide Channel A, SCSI Id=7, PCI-X 101-133Mhz, 512 SCBs Uh, how are you using SATA disks on a SCSI controller? > I am seeing this sort of thing in /var/log/messages: > Mar 12 09:21:58 BFPS kernel: ata2.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x2 frozen > Mar 12 09:21:58 BFPS kernel: ata2.00: cmd ea/00:00:00:00:00/00:00:00:00:00/a0 tag 0 > Mar 12 09:21:58 BFPS kernel: res 40/00:00:00:4f:c2/00:00:00:00:00/00 Emask 0x4 (timeout) > Mar 12 09:21:58 BFPS kernel: ata2.00: status: { DRDY } > Mar 12 09:22:03 BFPS kernel: ata2: port is slow to respond, please be patient (Status 0xd0) > Mar 12 09:22:08 BFPS kernel: ata2: device not ready (errno=-16), forcing hardreset > Mar 12 09:22:08 BFPS kernel: ata2: hard resetting link > Mar 12 09:22:08 BFPS kernel: ata2: SATA link up 3.0 Gbps (SStatus 123 SControl 300) > Mar 12 09:22:39 BFPS kernel: ata2.00: qc timeout (cmd 0xec) > Mar 12 09:22:39 BFPS kernel: ata2.00: failed to IDENTIFY (I/O error, err_mask=0x5) > Mar 12 09:22:39 BFPS kernel: ata2.00: revalidation failed (errno=-5) > Mar 12 09:22:39 BFPS kernel: ata2: failed to recover some devices, retrying in 5 secs > Mar 12 09:22:44 BFPS kernel: ata2: hard resetting link You are experiencing one of the following: Drive failure Cabling failure Controller failure Buggy drive firmware Buggy drivers BTW, the ST31000333AS is one of the drives that were shipped with buggy firmware causing timeouts like the ones you are seeing. You should check with Seagate that you have the latest firmware flashed to those drives. > Mar 12 09:28:07 BFPS smartd[3183]: Device: /dev/sdb, not capable of SMART self-check > Mar 12 09:28:07 BFPS smartd[3183]: Sending warning via mail to root ... > Mar 12 09:28:07 BFPS smartd[3183]: Warning via mail to root: successful You really need to get SMART checking working as well. Checking the status of the drive (try smartctl) may help you isolate your problem. Which, BTW, does not appear to be the same as the thread starter's. -Dave -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html ^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: High IO Wait with RAID 1 2009-03-12 23:46 High IO Wait with RAID 1 Ryan Wagoner 2009-03-13 0:48 ` Alain Williams @ 2009-03-13 14:48 ` John Robinson 1 sibling, 0 replies; 14+ messages in thread From: John Robinson @ 2009-03-13 14:48 UTC (permalink / raw) To: Ryan Wagoner; +Cc: linux-raid On 12/03/2009 23:46, Ryan Wagoner wrote: [...] > Both systems exhibit the same issues on the RAID 1 drives. That rules > out the drive brand and controller card. During any IO intensive > process the IO wait will raise and the system load will climb. I'm sorry if this sounds flippant, but what did you expect? > I've > had the IO wait as high as 70% and the load at 13+ while migrating a > vmdk file with vmware-vdiskmanager. You can easily recreate the issue > with bonnie++. > > I can perform the same disk intensive operation on the RAID 5 array > with almost no io wait or load. What is the deal with this? Is there > something I can tweak? I suspect your RAID-5 array has higher thoughput available - reading and writing across 3 discs rather than 2 - and what you're doing isn't quite maxing out its throughput, whereas it does on the 2-disc RAID-1. I imagine you would see the same thing on a single disc. Bear in mind that iowait time needn't be wasted; run a few copies of something CPU intensive at the same time and you will see zero iowait. High system load isn't necessarily a problem either; I once had a busy web server where the system load went from about 5 one day to over 200 the next. Cue much panicking trying to find out what had happened. Turned out the web designers had made the home page 70K instead of 60K, so a lot of httpd processes sending to slow links were stalled when previously the whole lot would have been in network buffers. It still worked fine in that there was no detectable performance problem, it was just an alarming-looking system load. Cheers, John. ^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: High IO Wait with RAID 1
@ 2009-03-13 18:02 David Lethe
2009-03-13 18:29 ` Ryan Wagoner
0 siblings, 1 reply; 14+ messages in thread
From: David Lethe @ 2009-03-13 18:02 UTC (permalink / raw)
To: Ryan Wagoner, Bill Davidsen; +Cc: Alain Williams, linux-raid
-----Original Message-----
From: "Ryan Wagoner" <rswagoner@gmail.com>
Subj: Re: High IO Wait with RAID 1
Date: Fri Mar 13, 2009 12:45 pm
Size: 2K
To: "Bill Davidsen" <davidsen@tmr.com>
cc: "Alain Williams" <addw@phcomp.co.uk>; "linux-raid@vger.kernel.org" <linux-raid@vger.kernel.org>
Yeah I understand the basics to RAID and the effect cache has on
performance. It just seems that RAID 1 should offer better write
performance than a 3 drive RAID 5 array. However I haven't run the
numbers so I could be wrong.
It could be just that I expect too much from RAID 1. I'm debating
about reloading the box with RAID 10 across 160GB of the 4 drives
(160GB and 320GB) and a mirror on the remaining space. In theory this
should gain me write performance.
Thanks,
Ryan
On Fri, Mar 13, 2009 at 11:22 AM, Bill Davidsen <davidsen@tmr.com> wrote:
> Ryan Wagoner wrote:
>>
>> I'm glad I'm not the only one experiencing the issue. Luckily the
>> issues on both my systems aren't as bad. I don't have any errors
>> showing in /var/log/messages on either system. I've been trying to
>> track down this issue for about a year now. I just recently my the
>> connection with RAID 1 and mdadm when copying data on the second
>> system.
>>
>> Unfortunately it looks like the fix is to avoid software RAID 1. I
>> prefer software RAID over hardware RAID on my home systems for the
>> flexibility it offers, especially since I can easily move the disks
>> between systems in the case of hardware failure.
>>
>> If I can find time to migrate the VMs, which run my web sites and
>> email to another machine, I'll reinstall the one system utilizing RAID
>> 1 on the LSI controller. It doesn't support RAID 5 so I'm hoping I can
>> just pass the remaining disks through.
>>
FYi - you can potentially get a big performance penalty when running a LSI raid card in jbod mode. The impact varies depending on a lot of things .. Try loading the jbod fimware on the card if it supports this and re run benchmarks
david
^ permalink raw reply [flat|nested] 14+ messages in thread* Re: High IO Wait with RAID 1 2009-03-13 18:02 David Lethe @ 2009-03-13 18:29 ` Ryan Wagoner 2009-03-13 22:10 ` David Rees 0 siblings, 1 reply; 14+ messages in thread From: Ryan Wagoner @ 2009-03-13 18:29 UTC (permalink / raw) To: David Lethe; +Cc: Bill Davidsen, Alain Williams, linux-raid The card has the latest non RAID firmware loaded on it. The LSI 1068 model comes default from Supermicro with the non RAID firmware. It only has an ARM processor capable of RAID 0 or 1 if you load the RAID firmware. The other system with the onboard ICH controller exhibits the same symptoms so I think my card is configured correctly. The interesting part of this is I can kick off a resync on all three RAID volumes and the system load and io wait is low. The rebuild rate is 85M/s for the RAID 5 volume and 65M/s for the RAID 1 volumes, which is the max each individual drive can do. Ryan On Fri, Mar 13, 2009 at 1:02 PM, David Lethe <david@santools.com> wrote: > -----Original Message----- > > From: "Ryan Wagoner" <rswagoner@gmail.com> > Subj: Re: High IO Wait with RAID 1 > Date: Fri Mar 13, 2009 12:45 pm > Size: 2K > To: "Bill Davidsen" <davidsen@tmr.com> > cc: "Alain Williams" <addw@phcomp.co.uk>; "linux-raid@vger.kernel.org" <linux-raid@vger.kernel.org> > > Yeah I understand the basics to RAID and the effect cache has on > performance. It just seems that RAID 1 should offer better write > performance than a 3 drive RAID 5 array. However I haven't run the > numbers so I could be wrong. > > It could be just that I expect too much from RAID 1. I'm debating > about reloading the box with RAID 10 across 160GB of the 4 drives > (160GB and 320GB) and a mirror on the remaining space. In theory this > should gain me write performance. > > Thanks, > Ryan > > On Fri, Mar 13, 2009 at 11:22 AM, Bill Davidsen <davidsen@tmr.com> wrote: >> Ryan Wagoner wrote: >>> >>> I'm glad I'm not the only one experiencing the issue. Luckily the >>> issues on both my systems aren't as bad. I don't have any errors >>> showing in /var/log/messages on either system. I've been trying to >>> track down this issue for about a year now. I just recently my the >>> connection with RAID 1 and mdadm when copying data on the second >>> system. >>> >>> Unfortunately it looks like the fix is to avoid software RAID 1. I >>> prefer software RAID over hardware RAID on my home systems for the >>> flexibility it offers, especially since I can easily move the disks >>> between systems in the case of hardware failure. >>> >>> If I can find time to migrate the VMs, which run my web sites and >>> email to another machine, I'll reinstall the one system utilizing RAID >>> 1 on the LSI controller. It doesn't support RAID 5 so I'm hoping I can >>> just pass the remaining disks through. >>> > > FYi - you can potentially get a big performance penalty when running a LSI raid card in jbod mode. The impact varies depending on a lot of things .. Try loading the jbod fimware on the card if it supports this and re run benchmarks > > david > > -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html ^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: High IO Wait with RAID 1 2009-03-13 18:29 ` Ryan Wagoner @ 2009-03-13 22:10 ` David Rees 0 siblings, 0 replies; 14+ messages in thread From: David Rees @ 2009-03-13 22:10 UTC (permalink / raw) To: Ryan Wagoner; +Cc: David Lethe, Bill Davidsen, Alain Williams, linux-raid On Fri, Mar 13, 2009 at 11:29 AM, Ryan Wagoner <rswagoner@gmail.com> wrote: > The other system with the onboard ICH controller exhibits the same > symptoms so I think my card is configured correctly. The interesting > part of this is I can kick off a resync on all three RAID volumes and > the system load and io wait is low. The rebuild rate is 85M/s for the > RAID 5 volume and 65M/s for the RAID 1 volumes, which is the max each > individual drive can do. The load from rebuilding the raid doesn't show up in system load or io wait as it's done in-kernel. If you run some other IO intensive processes during the rebuild you should notice that it will run a bit slower and io wait should be higher. -Dave ^ permalink raw reply [flat|nested] 14+ messages in thread
end of thread, other threads:[~2009-03-13 22:10 UTC | newest]
Thread overview: 14+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2009-03-12 23:46 High IO Wait with RAID 1 Ryan Wagoner
2009-03-13 0:48 ` Alain Williams
2009-03-13 3:21 ` Ryan Wagoner
2009-03-13 9:39 ` Robin Hill
2009-03-13 10:17 ` Alain Williams
[not found] ` <7d86ddb90903130519p4268dc33vc8ad42b53aefa2e2@mail.gmail.com>
2009-03-13 12:21 ` Fwd: " Ryan Wagoner
2009-03-13 16:22 ` Bill Davidsen
2009-03-13 17:42 ` Ryan Wagoner
2009-03-13 18:37 ` David Rees
2009-03-13 18:42 ` David Rees
2009-03-13 14:48 ` John Robinson
2009-03-13 18:02 David Lethe
2009-03-13 18:29 ` Ryan Wagoner
2009-03-13 22:10 ` David Rees
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