Re: some ?? re failed disk and resyncing of array

On Sun, 01 Feb 2009 14:41:37 -0500, "Bill Davidsen" [off-list ref]
said:

whollygoat@letterboxes.org wrote:

quoted

On Sat, 31 Jan 2009 10:38:22 +0000, "David Greaves" [off-list ref]
said:
  

quoted

whollygoat@letterboxes.org wrote:
    

quoted

On a boot a couple of days ago, mdadm failed a disk and
started resyncing to spare (raid5, 6 drives, 5 active, 1
spare).  smartctl -H <disk> returned info (can't remember
the exact text) that made me suspect the drive was
fine, but the data connection was bad.  Sure enough the
data cable was damaged.  Replaced the cable and smartctl
sees the disk just fine and reports no errors.

- I'd like to readd the drive as a spare.  Is it enough
to "mdadm --add /dev/hdk" or do I need to prep the drive to
remove any data that said where it previously belonged
in the array?
      

That should work.
Any issues and you can zero the superblock (man mdadm)
No need to zero the disk.
    

Would --re-add be better?

  

I don't think do. And I would zero the superblock. The more detail you 
put into preventing unwanted autodetection the fewer learning 
experiences you will have.

Will do

quoted

fly:~# mdadm -D /dev/md0

[snip]

quoted

   Raid Devices : 5
  Total Devices : 5
Preferred Minor : 0
    Persistence : Superblock is persistent

  Intent Bitmap : Internal

    Update Time : Fri Jan 30 15:52:01 2009
          State : active
 Active Devices : 5
Working Devices : 5
 Failed Devices : 0
  Spare Devices : 0

[snip]

quoted

    Number   Major   Minor   RaidDevice State
       0      33        1        0      active sync   /dev/hde1
       1      34        1        1      active sync   /dev/hdg1
       2      56        1        2      active sync   /dev/hdi1
       5      89        1        3      active sync   /dev/hdo1
       6      88        1        4      active sync   /dev/hdm1


fly:~# mdadm -E /dev/hdo1

[snip]

quoted

    Array Slot : 5 (0, 1, 2, failed, failed, 3, 4)
   Array State : uuuUu 2 failed
--------- end output -------------

Why does the "Array Slot" field show 7 slots?  And why
does the field "Array State" show 2 failed?  There 
ever only were 6 disks in the array.  Only one of those
is currently missing.  mdadm -D above doesn't list any
failed devices in the "Failed Devices" field.

  

No idea, but did you explicitly remove the failed drive? Was there a 
failed drive at some time in the past?

No explicit removal.  Maybe I should have.  I let it rebuild
then shutdown to see if it was just something like cabling.
After dealing with the cabling problem and rebooting mdadm -D
didn't show any failed drives, just as above, so it never occurred
to me to remove the drive.

Is there anything I can do to fix the information reported by
mdadm -E <component device>?  Maybe when I add the old drive
as the new spare it will be taken care of?

Thanks,

wg

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