Yep. If a RAID1 drive drops from the set, then gets reconnected, a resync will occur which can take hours - days. more /proc/mdstat
Originally Posted by sim085
If you want to see data being written to both drives, any io-monitoring tool should show it. I use saidar to get a warm fuzzy, but it isn't much use beyond that.
I took notes during and after setting up my RAID arrays. Haven't needed more than these the last 8 yrs. Clearly, modify each command for your situation:
These are just the commands not a script. Each has a specific purpose. Simple stuff for the most part.
sudo mdadm --detail /dev/mdX # See what is up!
sudo mdadm /dev/mdX -a /dev/sdf1 # if 1 disk drops out
sudo mdadm --assemble /dev/mdX -v --force # if the array is migrated to a new box
# RAID Maintenance - run the "check" weekly
echo check > /sys/block/mdX/md/sync_action
echo repair > /sys/block/mdX/md/sync_action