Re: MD Raid10 recovery results in "attempt to access beyond end of device"

[NeilBrown <neilb@suse.de>]

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On Fri, 22 Jun 2012 16:06:32 +0900 Christian Balzer <chibi@gol.com> wrote:

> 
> Hello,
> 
> the basics first:
> Debian Squeeze, custom 3.2.18 kernel.
> 
> The Raid(s) in question are:
> ---
> Personalities : [raid1] [raid10] 
> md4 : active raid10 sdd1[0] sdb4[5](S) sdl1[4] sdk1[3] sdj1[2] sdi1[1]
>       3662836224 blocks super 1.2 512K chunks 2 near-copies [5/5] [UUUUU]

I'm stumped by this.  It shouldn't be possible.

The size of the array is impossible.

If there are N chunks per device, then there are 5*N chunks on the whole
array, and there are are two copies of each data chunk, so
5*N/2 distinct data chunks, so that should be the size of the array.

So if we take the size of the array, divide by chunk size, multiply by 2,
divide by 5, we get N = the number of chunks per device.
i.e.
  N = (array_size / chunk_size)*2 / 5

If we plug in 3662836224 for the array size and 512 for the chunk size,
we get 2861590.8, which is not an integer.
i.e. impossible.

What does "mdadm --examine" of the various devices show?

NeilBrown


>       
> md3 : active raid10 sdh1[7] sdc1[0] sda4[5](S) sdg1[3] sdf1[2] sde1[6]
>       3662836224 blocks super 1.2 512K chunks 2 near-copies [5/4] [UUUU_]
>       [=====>...............]  recovery = 28.3% (415962368/1465134592) finish=326.2min speed=53590K/sec
> ---
> 
> Drives sda to sdd are on nVidia MCP55 and sde to sdl on SAS1068E, sdc to
> sdl are identical 1.5TB Seagates (about 2 years old, recycled from the
> previous incarnation of these machines) with a single partition spanning
> the whole drive like this:
> ---
> Disk /dev/sdc: 1500.3 GB, 1500301910016 bytes
> 255 heads, 63 sectors/track, 182401 cylinders
> Units = cylinders of 16065 * 512 = 8225280 bytes
> Sector size (logical/physical): 512 bytes / 512 bytes
> I/O size (minimum/optimal): 512 bytes / 512 bytes
> Disk identifier: 0x00000000
> 
>    Device Boot      Start         End      Blocks   Id  System
> /dev/sdc1               1      182401  1465136001   fd  Linux raid autodetect
> ---
> 
> sda and sdb are new 2TB Hitachi drives, partitioned like this:
> ---
> Disk /dev/sda: 2000.4 GB, 2000398934016 bytes
> 255 heads, 63 sectors/track, 243201 cylinders
> Units = cylinders of 16065 * 512 = 8225280 bytes
> Sector size (logical/physical): 512 bytes / 512 bytes
> I/O size (minimum/optimal): 512 bytes / 512 bytes
> Disk identifier: 0x000d53b0
> 
>    Device Boot      Start         End      Blocks   Id  System
> /dev/sda1   *           1       31124   249999360   fd  Linux raid autodetect
> /dev/sda2           31124       46686   124999680   fd  Linux raid autodetect
> /dev/sda3           46686       50576    31246425   fd  Linux raid autodetect
> /dev/sda4           50576      243201  1547265543+  fd  Linux raid autodetect
> ---
> 
> So the idea is to have 5 drives per each of the two Raid10s and one spare
> on that (intentionally over-sized) fourth partition of the bigger OS
> disks.
> 
> Some weeks ago a drive failed on the twin (identical everything, DRBD
> replication of those 2 RAIDs) of the machine in question and everything
> went according to the book, spare took over and things got rebuild, I
> replaced the failed drive (sdi) later:
> ---
> md4 : active raid10 sdi1[6](S) sdd1[0] sdb4[5] sdl1[4] sdk1[3] sdj1[2]
>       3662836224 blocks super 1.2 512K chunks 2 near-copies [5/5] [UUUUU]
> ---
> 
> Two days ago drive sdh on the machine that's having issues failed:
> ---
> Jun 20 18:22:39 borg03b kernel: [1383395.448043] sd 8:0:3:0: Device offlined - not ready after error recovery
> Jun 20 18:22:39 borg03b kernel: [1383395.448135] sd 8:0:3:0: rejecting I/O to offline device
> Jun 20 18:22:39 borg03b kernel: [1383395.452063] end_request: I/O error, dev sdh, sector 71
> Jun 20 18:22:39 borg03b kernel: [1383395.452063] md: super_written gets error=-5, uptodate=0
> Jun 20 18:22:39 borg03b kernel: [1383395.452063] md/raid10:md3: Disk failure on sdh1, disabling device.
> Jun 20 18:22:39 borg03b kernel: [1383395.452063] md/raid10:md3: Operation continuing on 4 devices.
> Jun 20 18:22:39 borg03b kernel: [1383395.527178] RAID10 conf printout:
> Jun 20 18:22:39 borg03b kernel: [1383395.527181]  --- wd:4 rd:5
> Jun 20 18:22:39 borg03b kernel: [1383395.527184]  disk 0, wo:0, o:1, dev:sdc1
> Jun 20 18:22:39 borg03b kernel: [1383395.527186]  disk 1, wo:0, o:1, dev:sde1
> Jun 20 18:22:39 borg03b kernel: [1383395.527189]  disk 2, wo:0, o:1, dev:sdf1
> Jun 20 18:22:39 borg03b kernel: [1383395.527191]  disk 3, wo:0, o:1, dev:sdg1
> Jun 20 18:22:39 borg03b kernel: [1383395.527193]  disk 4, wo:1, o:0, dev:sdh1
> Jun 20 18:22:39 borg03b kernel: [1383395.568037] RAID10 conf printout:
> Jun 20 18:22:39 borg03b kernel: [1383395.568040]  --- wd:4 rd:5
> Jun 20 18:22:39 borg03b kernel: [1383395.568042]  disk 0, wo:0, o:1, dev:sdc1
> Jun 20 18:22:39 borg03b kernel: [1383395.568045]  disk 1, wo:0, o:1, dev:sde1
> Jun 20 18:22:39 borg03b kernel: [1383395.568047]  disk 2, wo:0, o:1, dev:sdf1
> Jun 20 18:22:39 borg03b kernel: [1383395.568049]  disk 3, wo:0, o:1, dev:sdg1
> Jun 20 18:22:39 borg03b kernel: [1383395.568060] RAID10 conf printout:
> Jun 20 18:22:39 borg03b kernel: [1383395.568061]  --- wd:4 rd:5
> Jun 20 18:22:39 borg03b kernel: [1383395.568063]  disk 0, wo:0, o:1, dev:sdc1
> Jun 20 18:22:39 borg03b kernel: [1383395.568065]  disk 1, wo:0, o:1, dev:sde1
> Jun 20 18:22:39 borg03b kernel: [1383395.568068]  disk 2, wo:0, o:1, dev:sdf1
> Jun 20 18:22:39 borg03b kernel: [1383395.568070]  disk 3, wo:0, o:1, dev:sdg1
> Jun 20 18:22:39 borg03b kernel: [1383395.568072]  disk 4, wo:1, o:1, dev:sda4
> Jun 20 18:22:39 borg03b kernel: [1383395.568135] md: recovery of RAID array md3
> Jun 20 18:22:39 borg03b kernel: [1383395.568139] md: minimum _guaranteed_  speed: 20000 KB/sec/disk.
> Jun 20 18:22:39 borg03b kernel: [1383395.568142] md: using maximum available idle IO bandwidth (but not more than 500000 KB/sec) for recovery.
> Jun 20 18:22:39 borg03b kernel: [1383395.568155] md: using 128k window, over a total of 1465134592k.
> ---
> 
> OK, spare kicked, recovery underway (from the neighbors sdg and sdc), but then:
> ---
> Jun 21 02:29:29 borg03b kernel: [1412604.989978] attempt to access beyond end of device
> Jun 21 02:29:29 borg03b kernel: [1412604.989983] sdc1: rw=0, want=2930272128, limit=2930272002
> Jun 21 02:29:29 borg03b kernel: [1412604.990003] attempt to access beyond end of device
> Jun 21 02:29:29 borg03b kernel: [1412604.990009] sdc1: rw=16, want=2930272008, limit=2930272002
> Jun 21 02:29:29 borg03b kernel: [1412604.990013] md/raid10:md3: recovery aborted due to read error
> Jun 21 02:29:29 borg03b kernel: [1412604.990025] attempt to access beyond end of device
> Jun 21 02:29:29 borg03b kernel: [1412604.990028] sdc1: rw=0, want=2930272256, limit=2930272002
> Jun 21 02:29:29 borg03b kernel: [1412604.990032] md: md3: recovery done.
> Jun 21 02:29:29 borg03b kernel: [1412604.990035] attempt to access beyond end of device
> Jun 21 02:29:29 borg03b kernel: [1412604.990038] sdc1: rw=16, want=2930272136, limit=2930272002
> Jun 21 02:29:29 borg03b kernel: [1412604.990040] md/raid10:md3: recovery aborted due to read error
> ---
> 
> Why it would want to read data beyond the end of that device (and
> partition) is a complete mystery to me, if anything was odd with this Raid
> or its superblocks, surely the initial sync should have stumbled across
> this as well?
> 
> After this failure the kernel goes into a log frenzy:
> ---
> Jun 21 02:29:29 borg03b kernel: [1412605.744052] RAID10 conf printout:
> Jun 21 02:29:29 borg03b kernel: [1412605.744055]  --- wd:4 rd:5
> Jun 21 02:29:29 borg03b kernel: [1412605.744057]  disk 0, wo:0, o:1, dev:sdc1
> Jun 21 02:29:29 borg03b kernel: [1412605.744060]  disk 1, wo:0, o:1, dev:sde1
> Jun 21 02:29:29 borg03b kernel: [1412605.744062]  disk 2, wo:0, o:1, dev:sdf1
> Jun 21 02:29:29 borg03b kernel: [1412605.744064]  disk 3, wo:0, o:1, dev:sdg1
> ---
> repeating every second or so, until I "mdadm -r"ed the sda4 partition
> (former spare).
> 
> On the next day I replaced the failed sdh drive with another 2TB Hitachi
> (having only 1.5TB Seagates of dubious quality lying around), gave it the
> same single partition size as the other drives and added it to md3.
> 
> The resync failed in the same manner:
> ---
> Jun 21 20:59:06 borg03b kernel: [1479182.509914] attempt to access beyond end of device
> Jun 21 20:59:06 borg03b kernel: [1479182.509920] sdc1: rw=0, want=2930272128, limit=2930272002
> Jun 21 20:59:06 borg03b kernel: [1479182.509931] attempt to access beyond end of device
> Jun 21 20:59:06 borg03b kernel: [1479182.509933] attempt to access beyond end of device
> Jun 21 20:59:06 borg03b kernel: [1479182.509937] sdc1: rw=0, want=2930272256, limit=2930272002
> Jun 21 20:59:06 borg03b kernel: [1479182.509942] md: md3: recovery done.
> Jun 21 20:59:06 borg03b kernel: [1479182.509948] sdc1: rw=16, want=2930272008, limit=2930272002
> Jun 21 20:59:06 borg03b kernel: [1479182.509952] md/raid10:md3: recovery aborted due to read error
> Jun 21 20:59:06 borg03b kernel: [1479182.509963] attempt to access beyond end of device
> Jun 21 20:59:06 borg03b kernel: [1479182.509965] sdc1: rw=16, want=2930272136, limit=2930272002
> Jun 21 20:59:06 borg03b kernel: [1479182.509968] md/raid10:md3: recovery aborted due to read error
> ---
> 
> I've now scrounged up an identical 1.5TB drive and added it to the Raid
> (the recovery visible in the topmost mdstat). 
> If that fails as well, I'm completely lost as to what's going on, if it
> succeeds though I guess we're looking at a subtle bug. 
> 
> I didn't find anything like this mentioned in the archives before, any and
> all feedback would be most welcome.
> 
> Regards,
> 
> Christian


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