On 05/16/2017 04:25 PM, NeilBrown wrote:
On Tue, May 09 2017, Ram Ramesh wrote:
Today, I noticed that my RAID6 md0 was assembled in degraded state with
two drives in failed state after a pm-suspend and restart. Both of these
drives were attached toSAS9211-8I controller. The other drives are
attached to motherboard. I have not had this on a normal boot/reboot.
Also, in this particular case, mythtv recording was going on when
suspended and therefore as soon as resumed that used this md0.
Upon inspection, it appears (I am not sure here) that mdadm assembled
the array even before the drives were ready to be used. All I had to do
was to remove and re-add them to bring the array back to "good" state. I
am wondering if there is a way to tell mdadm to wait for all drives to
be ready before assembling. Also, if there is something that I can add
to resume scripts that will help, please let me know.
Kernel: Linux zym 3.13.0-106-generic #153-Ubuntu SMP
mdadm - v3.2.5 - 18th May 2012
Failed drives are HGST NAS and WD Gold with less than a year of usage.
So I doubt they are bad drives by any means.
This is a question that needs to be addressed by your distro. mdadm
just does what it is told to do by init/udev/systemd scripts.
The preferred way for array startup to happen is that when udev
discovers a new device, "mdadm --incremental $DEV" is run, and mdadm
includes the device into an array as appropriate. mdadm will not
normally activate the array until all expected devices have appeared.
After some timeout "mdadm -IRs" or "mdadm --run /dev/mdXX" can be run to
start the array even though it is degraded.
The udev-* scripts and systemd/* unit files provided with current
upstream mdadm do this, with a 30 second timeout.
If a given distro doesn't use these scripts, you need to take it up
with them.
NeilBrown
Neil,
Thanks. I was hoping that there is something that I can add to
mdadm.conf that will make this work. That is why I checked here, as my
mdadm expertise is liminited. Anyway, it appears that the problem is due
ext4lazyinit which accesses md instantaneously after resume. I will take
this up with the distro folks. My machine badly needs an upgrade. I
think it is time
Ramesh
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