mismatch_cnt != 0, member content mismatch, but md says the mirror is good

Michael ODonnell michael.odonnell at comcast.net
Mon Feb 22 13:39:41 EST 2010



Ruh-rohhh....

>/var/log/messages:   Feb 21 04:22:02 sbgrid-dev-architect kernel: md: syncing RAID array md0
>/var/log/messages:   Feb 21 04:22:02 sbgrid-dev-architect kernel: md: syncing RAID array md3
>/var/log/messages.1: Feb 14 04:22:02 sbgrid-dev-architect kernel: md: syncing RAID array md2
>/var/log/messages.1: Feb 14 04:22:02 sbgrid-dev-architect kernel: md: syncing RAID array md0
>/var/log/messages.1: Feb 14 04:22:02 sbgrid-dev-architect kernel: md: syncing RAID array md3
>/var/log/messages.2: Feb 7  04:22:01 sbgrid-dev-architect kernel: md: syncing RAID array md0
>/var/log/messages.2: Feb 7  04:22:01 sbgrid-dev-architect kernel: md: syncing RAID array md3
>/var/log/messages.3: Jan 31 04:22:02 sbgrid-dev-architect kernel: md: syncing RAID array md2
>/var/log/messages.3: Jan 31 04:22:02 sbgrid-dev-architect kernel: md: syncing RAID array md0
>/var/log/messages.3: Jan 31 04:22:02 sbgrid-dev-architect kernel: md: syncing RAID array md3
>/var/log/messages.4: Jan 24 04:22:06 sbgrid-dev-architect kernel: md: syncing RAID array md0
>/var/log/messages.4: Jan 24 04:22:06 sbgrid-dev-architect kernel: md: syncing RAID array md3
>
>That's a CentOS 5.4 x86_64 box.

Ours are, too.

So far, then, it's looking like every Sunday at 4:22 all the RAIDs
(all types or just RAID1?) in standard x86_64 CentOS5.4 (and RHAT?)
boxes are broken and then resync'd.  This is presumably unnecessary
and unintentional.  The harm is that until the resync operations
complete (large devices can take hours) the filesystems on those
RAIDs are essentially as vulnerable to HW faults as they'd be on any
single disk.  (Interactive responsiveness is usually significantly
reduced, as well - important in cases such as ours with customers
active at all hours, but maybe less so in a 9-to-5 environment).

We'll probably disable that "helpful" weekly script on our machines
until we have a better handle on this (or a fix).
 


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