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* raid5 reshape/resync
@ 2007-11-24 11:02 Nagilum
  2007-11-25 19:04 ` Nagilum
  0 siblings, 1 reply; 9+ messages in thread
From: Nagilum @ 2007-11-24 11:02 UTC (permalink / raw)
  To: linux-raid

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Hi,
I'm running 2.6.23.8 x86_64 using mdadm v2.6.4.
I was adding a disk (/dev/sdf) to an existing raid5 (/dev/sd[a-e] -> md0)
During that reshape (at around 4%) /dev/sdd reported read errors and  
went offline.
I replaced /dev/sdd with a new drive and tried to reassemble the array  
(/dev/sdd was shown as removed and now as spare).
Assembly worked but it would not run unless I use --force.
Since I'm always reluctant to use force I put the bad disk back in,  
this time as /dev/sdg . I re-added the drive and could run the array.  
The array started to resync (since the disk can be read until 4%) and  
then I marked the disk as failed. Now the array is "active, degraded,  
recovering":

nas:~# mdadm -Q --detail /dev/md0
/dev/md0:
         Version : 00.91.03
   Creation Time : Sat Sep 15 21:11:41 2007
      Raid Level : raid5
      Array Size : 1953234688 (1862.75 GiB 2000.11 GB)
   Used Dev Size : 488308672 (465.69 GiB 500.03 GB)
    Raid Devices : 6
   Total Devices : 7
Preferred Minor : 0
     Persistence : Superblock is persistent

     Update Time : Sat Nov 24 10:10:46 2007
           State : active, degraded, recovering
  Active Devices : 5
Working Devices : 6
  Failed Devices : 1
   Spare Devices : 1

          Layout : left-symmetric
      Chunk Size : 16K

  Reshape Status : 19% complete
   Delta Devices : 1, (5->6)

            UUID : 25da80a6:d56eb9d6:0d7656f3:2f233380
          Events : 0.726347

     Number   Major   Minor   RaidDevice State
        0       8        0        0      active sync   /dev/sda
        1       8       16        1      active sync   /dev/sdb
        2       8       32        2      active sync   /dev/sdc
        6       8       96        3      faulty spare rebuilding   /dev/sdg
        4       8       64        4      active sync   /dev/sde
        5       8       80        5      active sync   /dev/sdf

        7       8       48        -      spare   /dev/sdd

iostat:
Device:            tps    kB_read/s    kB_wrtn/s    kB_read    kB_wrtn
sda             129.48      1498.01      1201.59       7520       6032
sdb             134.86      1498.01      1201.59       7520       6032
sdc             127.69      1498.01      1201.59       7520       6032
sdd               0.40         0.00         3.19          0         16
sde             111.55      1498.01      1201.59       7520       6032
sdf             117.73         0.00      1201.59          0       6032
sdg               0.00         0.00         0.00          0          0

What I find somewhat confusing/disturbing is that does not appear to  
utilize /dev/sdd. What I see here could be explained by md doing a  
RAID5 resync from the 4 drives sd[a-c,e] to sd[a-c,e,f] but I would  
have expected it to use the new spare sdd for that. Also the speed is  
unusually low which seems to indicate a lot of seeking as if two  
operations are happening at the same time.
Also when I look at the data rates it looks more like the reshape is  
continuing even though one drive is missing (possible but risky).
Can someone relief my doubts as to whether md does the right thing here?
Thanks,

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^ permalink raw reply	[flat|nested] 9+ messages in thread

end of thread, other threads:[~2007-12-19 21:04 UTC | newest]

Thread overview: 9+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2007-11-24 11:02 raid5 reshape/resync Nagilum
2007-11-25 19:04 ` Nagilum
2007-11-29  5:48   ` Neil Brown
2007-12-01 14:48     ` Nagilum
2007-12-11 21:56       ` Nagilum
2007-12-16 13:16         ` Janek Kozicki
2007-12-18 10:09           ` Nagilum
2007-12-19  4:50             ` raid5 reshape/resync - BUGREPORT Janek Kozicki
2007-12-19 21:04               ` raid5 reshape/resync - BUGREPORT/PROBLEM Nagilum

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