Cutting power without breaking RAID

[Niccolo Rigacci <niccolo@rigacci.org>]

Hello,

I'm facing this problem:

when my Linux box detects a POWER FAIL event from the UPS, it 
starts a normal shutdown. Just before the normal kernel poweroff, 
it sends to the UPS a signal on the serial line which says 
"cut-off the power to the server and switch-off the UPS".

This is required to reboot the server as soon as the power is 
restored.

The problem is that the root partition is on top of a RAID-1 
filesystem which is still mounted when the program that kills the 
power is run, so the system goes down with a non clean RAID 
volume.

What can be the proper action to do before killing the power to 
ensure that RAID will remain clean? It seems that remounting 
the partition read-only is not sufficient.

-- 
Niccolo Rigacci
Firenze - Italy

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