Re: RAID 1 resync with both members good.

[Richard Scobie <richard@sauce.co.nz>]

I could be way off the mark as I do not use Debian, but it is my 
understanding that they install a script which performs regular (weekly? 
monthly?) checks on md arrays.

These will show as resync events.

Regards,

Richard

Simon Jackson wrote:
> Could someone help me understand why I am seeing the following
> behaviour?
> 
> We use a pair of disks with 3 RAID1 partitions inside an appliance
> system.
> 
> During testing we have seen some instances of the RAID devices resyncing
> even though both members are marked as good in the output of
> /proc/mdstat.
> 
> merc:~# cat /proc/mdstat 
> Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5]
> [raid4] [raid10] 
> md2 : active raid1 sda3[0] sdb3[1]
> 7823552 blocks [2/2] [UU]
> resync=DELAYED
> md0 : active raid1 sda5[0] sdb5[1]
> 7823552 blocks [2/2] [UU]
> md1 : active raid1 sda6[0] sdb6[1]
> 55841792 blocks [2/2] [UU]
> [=================>...] resync = 88.8% (49606848/55841792) finish=8.4min
> speed=12256K/sec
> unused devices: <none>
> 
> 
> Why would a resync occur if both members are marked us good?
> 
> What we usually see when a drive is failed removed and readded is that
> the resync marks the new drive as down "_" until the resync completes.
> 
> Firstly why is a resync occurring when both drives are still good in the
> raid set?  Is this be expected behaviour or an indication of an
> underlying problem.
> 
> Thanks for any assistance.
> 
> Using Debian 2.6.26-1 
> 
> Thanks Simon.  
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