On Fri, 01 Nov 2013 13:59:40 +0100 Jack Wang [off-list ref] wrote:

Hi Neil and all,

Is there anyway to know:

1. How often does a raid start to resync?

Look at your logs?

2. How many bytes did it resync?

Look at "mismatch_cnt" in sysfs (and multiply by 512).

NeilBrown

If not, for the first one, I think we cound add field into mddev like
resync_counter, increase when resync done, and annother field into
md_rdev to track how many bytes synced to the outdated disk?

Regards,
Jack