* RAID10 failed with two disks
@ 2011-08-22 10:39 Piotr Legiecki
2011-08-22 11:09 ` NeilBrown
0 siblings, 1 reply; 7+ messages in thread
From: Piotr Legiecki @ 2011-08-22 10:39 UTC (permalink / raw)
To: linux-raid
Hi
I'v got RAID10 on 4 disks. Suddenly two of the disks failed (I doubt the
disks actually failed, rather it is a kernel failure or maybe
motherboard SATA controller)?
So after rebootig I cannot start the array. So my first question is: on
RAID10 (default layout) which disks may fail and still the array survive?
mdadm --examine /dev/sda1
/dev/sda1:
Magic : a92b4efc
Version : 00.90.00
UUID : fab2336d:71210520:990002ab:4fde9f0c (local to host bez)
Creation Time : Mon Aug 22 10:40:36 2011
Raid Level : raid10
Used Dev Size : 976759936 (931.51 GiB 1000.20 GB)
Array Size : 1953519872 (1863.02 GiB 2000.40 GB)
Raid Devices : 4
Total Devices : 4
Preferred Minor : 4
Update Time : Mon Aug 22 10:40:36 2011
State : clean
Active Devices : 2
Working Devices : 2
Failed Devices : 2
Spare Devices : 0
Checksum : d4ba8390 - correct
Events : 1
Layout : near=2, far=1
Chunk Size : 64K
Number Major Minor RaidDevice State
this 0 8 1 0 active sync /dev/sda1
0 0 8 1 0 active sync /dev/sda1
1 1 8 17 1 active sync /dev/sdb1
2 2 0 0 2 faulty
3 3 0 0 3 faulty
The last two disks (failed ones) are sde1 and sdf1.
So do I have any chances to get the array running or it is dead?
I've tried a few steps to run the array but with no luck.
Regards
P.
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: RAID10 failed with two disks 2011-08-22 10:39 RAID10 failed with two disks Piotr Legiecki @ 2011-08-22 11:09 ` NeilBrown 2011-08-22 11:42 ` Piotr Legiecki 0 siblings, 1 reply; 7+ messages in thread From: NeilBrown @ 2011-08-22 11:09 UTC (permalink / raw) To: Piotr Legiecki; +Cc: linux-raid On Mon, 22 Aug 2011 12:39:42 +0200 Piotr Legiecki <piotrlg@pum.edu.pl> wrote: > Hi > > I'v got RAID10 on 4 disks. Suddenly two of the disks failed (I doubt the > disks actually failed, rather it is a kernel failure or maybe > motherboard SATA controller)? > > So after rebootig I cannot start the array. So my first question is: on > RAID10 (default layout) which disks may fail and still the array survive? Not adjacent disks. > > mdadm --examine /dev/sda1 > /dev/sda1: > Magic : a92b4efc > Version : 00.90.00 > UUID : fab2336d:71210520:990002ab:4fde9f0c (local to host bez) > Creation Time : Mon Aug 22 10:40:36 2011 > Raid Level : raid10 > Used Dev Size : 976759936 (931.51 GiB 1000.20 GB) > Array Size : 1953519872 (1863.02 GiB 2000.40 GB) > Raid Devices : 4 > Total Devices : 4 > Preferred Minor : 4 > > Update Time : Mon Aug 22 10:40:36 2011 > State : clean > Active Devices : 2 > Working Devices : 2 > Failed Devices : 2 > Spare Devices : 0 > Checksum : d4ba8390 - correct > Events : 1 > > Layout : near=2, far=1 > Chunk Size : 64K > > Number Major Minor RaidDevice State > this 0 8 1 0 active sync /dev/sda1 > > 0 0 8 1 0 active sync /dev/sda1 > 1 1 8 17 1 active sync /dev/sdb1 > 2 2 0 0 2 faulty > 3 3 0 0 3 faulty > > The last two disks (failed ones) are sde1 and sdf1. > > So do I have any chances to get the array running or it is dead? Possible. Report "mdadm --examine" of all devices that you believe should be part of the array. NeilBrown > > I've tried a few steps to run the array but with no luck. > > Regards > P. > > -- > 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] 7+ messages in thread
* Re: RAID10 failed with two disks 2011-08-22 11:09 ` NeilBrown @ 2011-08-22 11:42 ` Piotr Legiecki 2011-08-22 12:01 ` NeilBrown 0 siblings, 1 reply; 7+ messages in thread From: Piotr Legiecki @ 2011-08-22 11:42 UTC (permalink / raw) To: NeilBrown; +Cc: linux-raid >> mdadm --examine /dev/sda1 >> /dev/sda1: >> Magic : a92b4efc >> Version : 00.90.00 >> UUID : fab2336d:71210520:990002ab:4fde9f0c (local to host bez) >> Creation Time : Mon Aug 22 10:40:36 2011 >> Raid Level : raid10 >> Used Dev Size : 976759936 (931.51 GiB 1000.20 GB) >> Array Size : 1953519872 (1863.02 GiB 2000.40 GB) >> Raid Devices : 4 >> Total Devices : 4 >> Preferred Minor : 4 >> >> Update Time : Mon Aug 22 10:40:36 2011 >> State : clean >> Active Devices : 2 >> Working Devices : 2 >> Failed Devices : 2 >> Spare Devices : 0 >> Checksum : d4ba8390 - correct >> Events : 1 >> >> Layout : near=2, far=1 >> Chunk Size : 64K >> >> Number Major Minor RaidDevice State >> this 0 8 1 0 active sync /dev/sda1 >> >> 0 0 8 1 0 active sync /dev/sda1 >> 1 1 8 17 1 active sync /dev/sdb1 >> 2 2 0 0 2 faulty >> 3 3 0 0 3 faulty >> >> The last two disks (failed ones) are sde1 and sdf1. >> >> So do I have any chances to get the array running or it is dead? > > Possible. > Report "mdadm --examine" of all devices that you believe should be part of > the array. /dev/sdb1: Magic : a92b4efc Version : 00.90.00 UUID : fab2336d:71210520:990002ab:4fde9f0c (local to host bez) Creation Time : Mon Aug 22 10:40:36 2011 Raid Level : raid10 Used Dev Size : 976759936 (931.51 GiB 1000.20 GB) Array Size : 1953519872 (1863.02 GiB 2000.40 GB) Raid Devices : 4 Total Devices : 4 Preferred Minor : 4 Update Time : Mon Aug 22 10:40:36 2011 State : clean Active Devices : 2 Working Devices : 2 Failed Devices : 2 Spare Devices : 0 Checksum : d4ba83a2 - correct Events : 1 Layout : near=2, far=1 Chunk Size : 64K Number Major Minor RaidDevice State this 1 8 17 1 active sync /dev/sdb1 0 0 8 1 0 active sync /dev/sda1 1 1 8 17 1 active sync /dev/sdb1 2 2 0 0 2 faulty 3 3 0 0 3 faulty /dev/sde1: Magic : a92b4efc Version : 00.90.00 UUID : 157a7440:4502f6db:990002ab:4fde9f0c (local to host bez) Creation Time : Fri Jun 3 12:18:33 2011 Raid Level : raid10 Used Dev Size : 976759936 (931.51 GiB 1000.20 GB) Array Size : 1953519872 (1863.02 GiB 2000.40 GB) Raid Devices : 4 Total Devices : 4 Preferred Minor : 4 Update Time : Sat Aug 20 03:06:27 2011 State : clean Active Devices : 4 Working Devices : 4 Failed Devices : 0 Spare Devices : 0 Checksum : c2f848c2 - correct Events : 24 Layout : near=2, far=1 Chunk Size : 64K Number Major Minor RaidDevice State this 2 8 65 2 active sync /dev/sde1 0 0 8 1 0 active sync /dev/sda1 1 1 8 17 1 active sync /dev/sdb1 2 2 8 65 2 active sync /dev/sde1 3 3 8 81 3 active sync /dev/sdf1 /dev/sdf1: Magic : a92b4efc Version : 00.90.00 UUID : 157a7440:4502f6db:990002ab:4fde9f0c (local to host bez) Creation Time : Fri Jun 3 12:18:33 2011 Raid Level : raid10 Used Dev Size : 976759936 (931.51 GiB 1000.20 GB) Array Size : 1953519872 (1863.02 GiB 2000.40 GB) Raid Devices : 4 Total Devices : 4 Preferred Minor : 4 Update Time : Sat Aug 20 03:06:27 2011 State : clean Active Devices : 4 Working Devices : 4 Failed Devices : 0 Spare Devices : 0 Checksum : c2f848d4 - correct Events : 24 Layout : near=2, far=1 Chunk Size : 64K Number Major Minor RaidDevice State this 3 8 81 3 active sync /dev/sdf1 0 0 8 1 0 active sync /dev/sda1 1 1 8 17 1 active sync /dev/sdb1 2 2 8 65 2 active sync /dev/sde1 3 3 8 81 3 active sync /dev/sdf1 smartd reported the sde and sdf disks are failed, but after rebooting it does not complain anymore. You say adjacent disks must be healthy for RAID10. So in my situation I have adjacent disks dead (sde and sdf). It does not look good. And does layout (near, far etc) influence on this rule: adjacent disk must be healthy? Regards P. ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: RAID10 failed with two disks 2011-08-22 11:42 ` Piotr Legiecki @ 2011-08-22 12:01 ` NeilBrown 2011-08-22 12:52 ` Piotr Legiecki 0 siblings, 1 reply; 7+ messages in thread From: NeilBrown @ 2011-08-22 12:01 UTC (permalink / raw) To: Piotr Legiecki; +Cc: linux-raid On Mon, 22 Aug 2011 13:42:54 +0200 Piotr Legiecki <piotrlg@pum.edu.pl> wrote: > >> mdadm --examine /dev/sda1 > >> /dev/sda1: > >> Magic : a92b4efc > >> Version : 00.90.00 > >> UUID : fab2336d:71210520:990002ab:4fde9f0c (local to host bez) > >> Creation Time : Mon Aug 22 10:40:36 2011 > >> Raid Level : raid10 > >> Used Dev Size : 976759936 (931.51 GiB 1000.20 GB) > >> Array Size : 1953519872 (1863.02 GiB 2000.40 GB) > >> Raid Devices : 4 > >> Total Devices : 4 > >> Preferred Minor : 4 > >> > >> Update Time : Mon Aug 22 10:40:36 2011 > >> State : clean > >> Active Devices : 2 > >> Working Devices : 2 > >> Failed Devices : 2 > >> Spare Devices : 0 > >> Checksum : d4ba8390 - correct > >> Events : 1 > >> > >> Layout : near=2, far=1 > >> Chunk Size : 64K > >> > >> Number Major Minor RaidDevice State > >> this 0 8 1 0 active sync /dev/sda1 > >> > >> 0 0 8 1 0 active sync /dev/sda1 > >> 1 1 8 17 1 active sync /dev/sdb1 > >> 2 2 0 0 2 faulty > >> 3 3 0 0 3 faulty > >> > >> The last two disks (failed ones) are sde1 and sdf1. > >> > >> So do I have any chances to get the array running or it is dead? > > > > Possible. > > Report "mdadm --examine" of all devices that you believe should be part of > > the array. > > /dev/sdb1: > Magic : a92b4efc > Version : 00.90.00 > UUID : fab2336d:71210520:990002ab:4fde9f0c (local to host bez) > Creation Time : Mon Aug 22 10:40:36 2011 > Raid Level : raid10 > Used Dev Size : 976759936 (931.51 GiB 1000.20 GB) > Array Size : 1953519872 (1863.02 GiB 2000.40 GB) > Raid Devices : 4 > Total Devices : 4 > Preferred Minor : 4 > > Update Time : Mon Aug 22 10:40:36 2011 > State : clean > Active Devices : 2 > Working Devices : 2 > Failed Devices : 2 > Spare Devices : 0 > Checksum : d4ba83a2 - correct > Events : 1 > > Layout : near=2, far=1 > Chunk Size : 64K > > Number Major Minor RaidDevice State > this 1 8 17 1 active sync /dev/sdb1 > > 0 0 8 1 0 active sync /dev/sda1 > 1 1 8 17 1 active sync /dev/sdb1 > 2 2 0 0 2 faulty > 3 3 0 0 3 faulty > > > > /dev/sde1: > Magic : a92b4efc > Version : 00.90.00 > UUID : 157a7440:4502f6db:990002ab:4fde9f0c (local to host bez) > Creation Time : Fri Jun 3 12:18:33 2011 > Raid Level : raid10 > Used Dev Size : 976759936 (931.51 GiB 1000.20 GB) > Array Size : 1953519872 (1863.02 GiB 2000.40 GB) > Raid Devices : 4 > Total Devices : 4 > Preferred Minor : 4 > > Update Time : Sat Aug 20 03:06:27 2011 > State : clean > Active Devices : 4 > Working Devices : 4 > Failed Devices : 0 > Spare Devices : 0 > Checksum : c2f848c2 - correct > Events : 24 > > Layout : near=2, far=1 > Chunk Size : 64K > > Number Major Minor RaidDevice State > this 2 8 65 2 active sync /dev/sde1 > > 0 0 8 1 0 active sync /dev/sda1 > 1 1 8 17 1 active sync /dev/sdb1 > 2 2 8 65 2 active sync /dev/sde1 > 3 3 8 81 3 active sync /dev/sdf1 > > /dev/sdf1: > Magic : a92b4efc > Version : 00.90.00 > UUID : 157a7440:4502f6db:990002ab:4fde9f0c (local to host bez) > Creation Time : Fri Jun 3 12:18:33 2011 > Raid Level : raid10 > Used Dev Size : 976759936 (931.51 GiB 1000.20 GB) > Array Size : 1953519872 (1863.02 GiB 2000.40 GB) > Raid Devices : 4 > Total Devices : 4 > Preferred Minor : 4 > > Update Time : Sat Aug 20 03:06:27 2011 > State : clean > Active Devices : 4 > Working Devices : 4 > Failed Devices : 0 > Spare Devices : 0 > Checksum : c2f848d4 - correct > Events : 24 > > Layout : near=2, far=1 > Chunk Size : 64K > > Number Major Minor RaidDevice State > this 3 8 81 3 active sync /dev/sdf1 > > 0 0 8 1 0 active sync /dev/sda1 > 1 1 8 17 1 active sync /dev/sdb1 > 2 2 8 65 2 active sync /dev/sde1 > 3 3 8 81 3 active sync /dev/sdf1 It looks like sde1 and sdf1 are unchanged since the "failure" which happened shortly after 3am on Saturday. So the data on them is probably good. It looks like someone (you?) tried to create a new array on sda1 and sdb1 thus destroying the old metadata (but probably not the data). I'm surprised that mdadm would have let you create a RAID10 with just 2 devices... Is that what happened? or something else? Anyway it looks as though if you run the command: mdadm --create /dev/md4 -l10 -n4 -e 0.90 /dev/sd{a,b,e,d}1 --assume-clean there is a reasonable change that /dev/md4 would have all your data. You should then fsck -fn /dev/md4 to check that it is all OK. If it is you can echo check > /sys/block/md4/md/sync_action to check if the mirrors are consistent. When it finished cat /sys/block/md4/md/mismatch_cnt will show '0' if all is consistent. If it is not zero but a small number, you can feel safe doing echo repair > /sys/block/md4/md/sync_action to fix it up. If it is a big number.... that would be troubling. > > > smartd reported the sde and sdf disks are failed, but after rebooting it > does not complain anymore. > > You say adjacent disks must be healthy for RAID10. So in my situation I > have adjacent disks dead (sde and sdf). It does not look good. > > And does layout (near, far etc) influence on this rule: adjacent disk > must be healthy? I didn't say adjacent disks must be healthy. Is said you cannot have adjacent disks both failing. This is not affected by near/far. It is a bit more subtle than that though. It is OK for 2nd and 3rd to both fail. But not 1st and 2nd or 3rd and 4th. NeilBrown > > > Regards > P. ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: RAID10 failed with two disks 2011-08-22 12:01 ` NeilBrown @ 2011-08-22 12:52 ` Piotr Legiecki 2011-08-22 23:56 ` NeilBrown 0 siblings, 1 reply; 7+ messages in thread From: Piotr Legiecki @ 2011-08-22 12:52 UTC (permalink / raw) To: NeilBrown; +Cc: linux-raid NeilBrown pisze: > It looks like sde1 and sdf1 are unchanged since the "failure" which happened > shortly after 3am on Saturday. So the data on them is probably good. And I think so. > It looks like someone (you?) tried to create a new array on sda1 and sdb1 > thus destroying the old metadata (but probably not the data). I'm surprised > that mdadm would have let you create a RAID10 with just 2 devices... Is > that what happened? or something else? Well, its me of course ;-) I've tried to run the array. It of course didn't allo me to create RAID10 on two disks only, so I have used mdadm --create .... missing missing parameters. But it didn't help. > Anyway it looks as though if you run the command: > > mdadm --create /dev/md4 -l10 -n4 -e 0.90 /dev/sd{a,b,e,d}1 --assume-clean Personalities : [raid1] [raid10] md4 : active (auto-read-only) raid10 sdf1[3] sde1[2] sdb1[1] sda1[0] 1953519872 blocks 64K chunks 2 near-copies [4/4] [UUUU] md3 : active raid1 sdc4[0] sdd4[1] 472752704 blocks [2/2] [UU] md2 : active (auto-read-only) raid1 sdc3[0] sdd3[1] 979840 blocks [2/2] [UU] md0 : active raid1 sdd1[0] sdc1[1] 9767424 blocks [2/2] [UU] md1 : active raid1 sdd2[0] sdc2[1] 4883648 blocks [2/2] [UU] Hura, hura, hura! ;-) Well, wonder why it didn't work for me ;-( > there is a reasonable change that /dev/md4 would have all your data. > You should then > fsck -fn /dev/md4 fsck issued some errors .... Illegal block #-1 (3126319976) in inode 14794786. IGNORED. Error while iterating over blocks in inode 14794786: Illegal indirect block found e2fsck: aborted md4 is read-only now. > to check that it is all OK. If it is you can > echo check > /sys/block/md4/md/sync_action > to check if the mirrors are consistent. When it finished > cat /sys/block/md4/md/mismatch_cnt > will show '0' if all is consistent. > > If it is not zero but a small number, you can feel safe doing > echo repair > /sys/block/md4/md/sync_action > to fix it up. > If it is a big number.... that would be troubling. A bit of magic as I can see. Would it not be reasonable to put those commands in mdadm? >> And does layout (near, far etc) influence on this rule: adjacent disk >> must be healthy? > > I didn't say adjacent disks must be healthy. Is said you cannot have > adjacent disks both failing. This is not affected by near/far. > It is a bit more subtle than that though. It is OK for 2nd and 3rd to both > fail. But not 1st and 2nd or 3rd and 4th. I see. Just like ordinary RAID1+0. First and second pair of the disks are RAID1, when both disks in that pair fail the mirror is dead. Wonder what happens when I create RAID10 on 6 disks? So we have got: sda1+sdb1 = RAID1 sdc1+sdd1 = RAID1 sde1+sdf1 = RAID1 Those three RAID1 are striped together in RAID0? And assuming each disk is 1TB, I have 3TB logical space? In such situation still the adjacent disks of each RAID1 both must not fail. And I still wonder why it happened? Hardware issue (motherboard)? Or kernel bug (2.6.26 - debian/lenny)? Thank you very nice for help. Regards Piotr ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: RAID10 failed with two disks 2011-08-22 12:52 ` Piotr Legiecki @ 2011-08-22 23:56 ` NeilBrown 2011-08-23 8:35 ` Piotr Legiecki 0 siblings, 1 reply; 7+ messages in thread From: NeilBrown @ 2011-08-22 23:56 UTC (permalink / raw) To: Piotr Legiecki; +Cc: linux-raid On Mon, 22 Aug 2011 14:52:50 +0200 Piotr Legiecki <piotrlg@pum.edu.pl> wrote: > NeilBrown pisze: > > It looks like sde1 and sdf1 are unchanged since the "failure" which happened > > shortly after 3am on Saturday. So the data on them is probably good. > > And I think so. > > > It looks like someone (you?) tried to create a new array on sda1 and sdb1 > > thus destroying the old metadata (but probably not the data). I'm surprised > > that mdadm would have let you create a RAID10 with just 2 devices... Is > > that what happened? or something else? > > Well, its me of course ;-) I've tried to run the array. It of course > didn't allo me to create RAID10 on two disks only, so I have used mdadm > --create .... missing missing parameters. But it didn't help. > > > > Anyway it looks as though if you run the command: > > > > mdadm --create /dev/md4 -l10 -n4 -e 0.90 /dev/sd{a,b,e,d}1 --assume-clean > > Personalities : [raid1] [raid10] > md4 : active (auto-read-only) raid10 sdf1[3] sde1[2] sdb1[1] sda1[0] > 1953519872 blocks 64K chunks 2 near-copies [4/4] [UUUU] > > md3 : active raid1 sdc4[0] sdd4[1] > 472752704 blocks [2/2] [UU] > > md2 : active (auto-read-only) raid1 sdc3[0] sdd3[1] > 979840 blocks [2/2] [UU] > > md0 : active raid1 sdd1[0] sdc1[1] > 9767424 blocks [2/2] [UU] > > md1 : active raid1 sdd2[0] sdc2[1] > 4883648 blocks [2/2] [UU] > > Hura, hura, hura! ;-) Well, wonder why it didn't work for me ;-( Looks good so far, but is you data safe? > > > > there is a reasonable change that /dev/md4 would have all your data. > > You should then > > fsck -fn /dev/md4 > > fsck issued some errors > .... > Illegal block #-1 (3126319976) in inode 14794786. IGNORED. > Error while iterating over blocks in inode 14794786: Illegal indirect > block found > e2fsck: aborted Mostly safe it seems .... assuming there were really serious things that you hid behind the "...". An "fsck -f /dev/md4" would probably fix it up. > > md4 is read-only now. > > > to check that it is all OK. If it is you can > > echo check > /sys/block/md4/md/sync_action > > to check if the mirrors are consistent. When it finished > > cat /sys/block/md4/md/mismatch_cnt > > will show '0' if all is consistent. > > > > If it is not zero but a small number, you can feel safe doing > > echo repair > /sys/block/md4/md/sync_action > > to fix it up. > > If it is a big number.... that would be troubling. > > A bit of magic as I can see. Would it not be reasonable to put those > commands in mdadm? Maybe one day. So much to do, so little time! > > >> And does layout (near, far etc) influence on this rule: adjacent disk > >> must be healthy? > > > > I didn't say adjacent disks must be healthy. Is said you cannot have > > adjacent disks both failing. This is not affected by near/far. > > It is a bit more subtle than that though. It is OK for 2nd and 3rd to both > > fail. But not 1st and 2nd or 3rd and 4th. > > I see. Just like ordinary RAID1+0. First and second pair of the disks > are RAID1, when both disks in that pair fail the mirror is dead. Like that - yes. > > Wonder what happens when I create RAID10 on 6 disks? So we have got: > sda1+sdb1 = RAID1 > sdc1+sdd1 = RAID1 > sde1+sdf1 = RAID1 > Those three RAID1 are striped together in RAID0? > And assuming each disk is 1TB, I have 3TB logical space? > In such situation still the adjacent disks of each RAID1 both must not > fail. This is correct assuming the default layout. If you asked for "--layout=n3" you would get a 3-way mirror over a1,b1,c1 and d1,e1,f1 and those would be raid0-ed. If you had 5 devices then you get data copied on sda1+sdb1 sdc1+sdd1 sde1+sda1 sdb1+sdc1 sdde+sde1 so is *any* pair of adjacent devices fail, you lose data. > > > And I still wonder why it happened? Hardware issue (motherboard)? Or > kernel bug (2.6.26 - debian/lenny)? Hard to tell without seeing kernel logs. Almost certainly a hardware issue of some sort. Maybe a loose or bumped cable. Maybe a power supply spike. Maybe a stray cosmic ray.... NeilBrown > > > Thank you very nice for help. > > Regards > Piotr ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: RAID10 failed with two disks 2011-08-22 23:56 ` NeilBrown @ 2011-08-23 8:35 ` Piotr Legiecki 0 siblings, 0 replies; 7+ messages in thread From: Piotr Legiecki @ 2011-08-23 8:35 UTC (permalink / raw) To: NeilBrown; +Cc: linux-raid >> Hura, hura, hura! ;-) Well, wonder why it didn't work for me ;-( > > Looks good so far, but is you data safe? I think so. fsck has found some errors and corrected them. resync done cat /sys/block/md4/md/mismatch_cnt 0 Looks good. > This is correct assuming the default layout. > If you asked for "--layout=n3" you would get a 3-way mirror over a1,b1,c1 and > d1,e1,f1 and those would be raid0-ed. And the question which one is the most efficient is beyond the scope of our subject I'm of course? Or maybe there is some general rule of thumb for this? The more disks the faster array should be *but* the more data to mirror at once when writing... Anyway my tests proved that RAID1 on two disks is *much* slower than RAID10 on 4 disks. RAID10 SATA can easily compete with HP SmartAray P410i/BBC SAS RAIDs (but in RAID1 only ;-)). Well, at least during iozone benchmarks. > If you had 5 devices then you get data copied on > sda1+sdb1 > sdc1+sdd1 > sde1+sda1 > sdb1+sdc1 > sdde+sde1 > > so is *any* pair of adjacent devices fail, you lose data. So from safety point of view there is need for more spare disks or go for RAID6. > Hard to tell without seeing kernel logs. Almost certainly a hardware issue > of some sort. Maybe a loose or bumped cable. Maybe a power supply spike. > Maybe a stray cosmic ray.... http://pastebin.com/iapZWm0S Those 'failed' disks are connected to motherboard SATA ports. I've got also Adaptec 1430 adapter with 2 free ports, maybe I should move those disks there. Thank you for all the help and time put into answering my questions. Piotr ^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2011-08-23 8:35 UTC | newest] Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2011-08-22 10:39 RAID10 failed with two disks Piotr Legiecki 2011-08-22 11:09 ` NeilBrown 2011-08-22 11:42 ` Piotr Legiecki 2011-08-22 12:01 ` NeilBrown 2011-08-22 12:52 ` Piotr Legiecki 2011-08-22 23:56 ` NeilBrown 2011-08-23 8:35 ` Piotr Legiecki
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