On Nov 10, 2013, at 10:34 PM, NeilBrown [off-list ref] wrote:

On Sun, 10 Nov 2013 13:17:21 -0600 Stan Hoeppner [off-list ref]
wrote:

quoted

Also, I see little/no value in running a scheduled mdadm check on a
RAID1 array.  Any problems with RAID1 will be due to one of the disks
beginning to fail in some mode, usually requiring sector relocation.

I think scrubbing has value on any RAID with redundancy.
The firmware can only relocate a sector if it reads it when it is marginal
but not yet completely lost.  If a sector is not read for a long time and
during that time the media degraded beyond recovery the firmware cannot do
anything.  But RAID1 can - it can get it from the other device.

NeilBrown

I think this is very relevant in my case. I typically offload a bulk of data to these drives, frequently using only some parts of it. So, it sounds like having check/scrubbing run on a schedule (how often is a reasonable frequency? every two weeks perhaps?) is a good idea after all.

Ivan