On Sun Sep 16, 2012 at 12:06:48 +0200, Niccolò Belli wrote:
> Il 15/09/2012 21:41, Robin Hill ha scritto:
> > If md hasn't failed the drive then either:
> > - md didn't get a read error
> > - md got a success message when re-writing the block
> > - there's a bug in md and it's not handled the error at all
>
> It seems it's case one, while manually verifying the checksums with
>
> for i in $(seq 50); do dd if=/dev/sda1 of=sda${i} bs=100000 count=50
> skip=$((($i-1)*50+10)) > /dev/null 2> /dev/null; dd if=/dev/sdb1
> of=sdb${i} bs=100000 count=50 skip=$((($i-1)*50+10)) > /dev/null 2>
> /dev/null; md5sum sda${i}; md5sum sdb${i}; echo; done
>
> I get this in syslog:
>
> Sep 15 23:50:09 asterisk kernel: [273828.407914] scsi_verify_blk_ioctl:
> 30 callbacks suppressed
> Sep 15 23:50:09 asterisk kernel: [273828.407920] dd: sending ioctl
> 80306d02 to a partition!
> Sep 15 23:50:09 asterisk kernel: [273828.407925] dd: sending ioctl
> 80306d02 to a partition!
> Sep 15 23:50:10 asterisk kernel: [273829.422247] ata3.00: exception
> Emask 0x0 SAct 0x0 SErr 0x0 action 0x0
> Sep 15 23:50:10 asterisk kernel: [273829.424071] ata3.00: BMDMA stat 0x44
> Sep 15 23:50:10 asterisk kernel: [273829.425855] ata3.00: failed
> command: READ DMA
> Sep 15 23:50:10 asterisk kernel: [273829.427625] ata3.00: cmd
> c8/00:00:68:17:00/00:00:00:00:00/e0 tag 0 dma 131072 in
> Sep 15 23:50:10 asterisk kernel: [273829.427627] res
> 51/40:00:90:17:00/40:00:00:00:00/e0 Emask 0x9 (media error)
> Sep 15 23:50:10 asterisk kernel: [273829.431184] ata3.00: status: { DRDY
> ERR }
> Sep 15 23:50:10 asterisk kernel: [273829.432992] ata3.00: error: { UNC }
> Sep 15 23:50:11 asterisk kernel: [273830.404203] ata3.00: configured for
> UDMA/133
> Sep 15 23:50:11 asterisk kernel: [273830.404217] ata3: EH complete
>
>
>
> but this is the output of the command:
>
>
> b7d4e3c3bb461a1aa6619c22ef11d072 sda1
> b7d4e3c3bb461a1aa6619c22ef11d072 sdb1
>
<- snip sets of identical checksums ->
>
> 94f883b45084b72cd9269a4821b2d509 sda50
> 94f883b45084b72cd9269a4821b2d509 sdb50
>
Okay, so it looks like the drive is managing to return the correct data
eventually (or it's returning some default value which has also been
written to the other mirror now).
> *BUT* if I start reading from the start of partition (+0 instead of +10
> in count=) I get a mismatch, on both md0 and md1 (which is supposed to
> be ok)!!!
>
> root@asterisk:~# i=1; dd if=/dev/sda1 of=sda${i} bs=100000 count=50
> skip=$((($i-1)*50+0)) > /dev/null 2> /dev/null; dd if=/dev/sdb1
> of=sdb${i} bs=100000 count=50 skip=$((($i-1)*50+0)) > /dev/null 2>
> /dev/null; md5sum sda${i}; md5sum sdb${i}
> 9f9f11ffeb0aed0abc8097417b293f41 sda1
> 394efde218ad700774bfcb3c43255529 sdb1
> root@asterisk:~# i=1; dd if=/dev/sda2 of=sda${i} bs=100000 count=50
> skip=$((($i-1)*50+0)) > /dev/null 2> /dev/null; dd if=/dev/sdb2
> of=sdb${i} bs=100000 count=50 skip=$((($i-1)*50+0)) > /dev/null 2>
> /dev/null; md5sum sda${i}; md5sum sdb${i}
> 8cb0b6fa2bf7f0f88a2a2a91598429d4 sda1
> 732c42e14b8e78930d08cdb4f1c49a40 sdb1
>
> Shouldn't raid1 match even at the very beginning of the partition?
>
No, the start of the partition will contain the md superblock (for 1.1
and 1.2 metadata formats), which will be slightly different for the two
devices.
Cheers,
Robin
--
___
( ' } | Robin Hill <robin@xxxxxxxxxxxxxxx> |
/ / ) | Little Jim says .... |
// !! | "He fallen in de water !!" |
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