Am 22.06.26 um 15:30 schrieb Andy Smith:
Hi,
The lack of an mdadm.conf should not cause you any issues. It's only
really used to set non-default options, give a monitoring email address
and so on.
O.k. I added an entry to mdadm.conf anyway, it shouldn't hurt at least.
udev incrementally assembles MDADM arrays as devices appear. It does not
need any configuration to do this. In order to end up in the situation
OP is in, I can only imagine that they rebooted and only one of the
LUKS devices was set up, so md0 proceeded in a degraded fashion with
that device.
What is confusing to me is how OP had an active mdadm array member with
an event count significantly *behind* the inactive one. It makes me
think that this may have happened more than once, with different single
LUKS devices being activated each time.
The switch of active and inactive devices happened definitely more than once.
The md array most likely switched between the LUKS devices at boot several
times, therefore the different event counts. The device with newer data of
course had the higher event count, as it was the one the data had been written
on in the weeks before the latest switch. My best guess is also that something
happened while the LUKS devices have been created which made md believe that
one device is not intact or available.
The mdadm monitor daemon runs by default and should email you about
degraded arrays. Without any configuration that would be sending to
root@localhost. OP should make sure that these emails will arrive
somewhere useful, or look into other ways of checking status of mdadm
arrays. What's happened here was likely trivial to fix at the
time of first problem but became a complete nightmare that likely
involved data loss (OP has backup of a device with unique data that
cannot be integrated).
Oh well, experience is never too expensive, a German saying goes... This issue
will not bug me again as much as it did. The next time I curse, it will be due
a different issue, I am sure. :-)
OP, after sorting out the monitoring I think you need to verify that
both LUKS devices are always successfully unlocked and available at boot
so that the RAID 1 assembles fully and properly.
mdmon is now set up, I tested that e-mails actually arrive.Latest news: The md
array survived a first reboot today.
I think it's unlikely that you have had a hardware failure of the
underlying drives, though you should of course check your logs and
smartctl for that. Given that LUKS is in use and is the most complicated
thing in your storage stack, I'd be looking into whether both LUKS
devices are being reliably created.
O.k.
If setting this system up from scratch my preference would be to do the
redundancy as near to the hardware as possible and the encryption as far
away as possible. So I'd put LUKS on md0, not md0 on two LUKS devices.
Thank you very much for your advice!
Paul
