mdam: email when re-syncing

[Franco Martelli <martellif67@gmail.com>]

Hi everybody,

I've mdadm that is running on Debian bookworm that it scans my RAID 5 
array. It happened that after a cycle of hard reboot due to system 
freeze, mdadm starts resync the array.

I noticed this looking at the red LED of the HDD activity almost always 
fired up and the "top" utility that it showed mdadm at 100% of cpu usage.

I dunno if all it's OK, here my /proc/mdstat output:

~# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4] [linear] [multipath] [raid0] 
[raid1] [raid10]
md0 : active raid5 sda1[0] sdc1[2] sdd1[3](S) sdb1[1]
      1953258496 blocks super 1.2 level 5, 512k chunk, algorithm 2 
[3/3] [UUU]

unused devices: <none>

I was amazed that mdadm doesn't warn me of the re-syncing process had 
started via an email. If I run:

~# mdadm --monitor --scan --test --oneshot

I've the email test-message in my inbox regularly. So is it possible to 
be warned via email when an array resync process has started? Of which 
RAID array failures does mdadm warn the user by sending an email?

Thanks in advance
Cheers

--
Franco Martelli