W dniu 22.08.2012 09:44, NeilBrown pisze:
[...]
So, again, ignoring that you possibly should not be using RAID for a
backup... how about using udev scripts to see when you plugin a drive,
and that script can check the UUID against any md arrays, and if it
matches, add it to the array....
I wrote a script making this work. It runs once a hour. I pass the parameter
with md device to the script. It checks the state of the array with "mdadm
--detail". If there is something wrong (State : degraded) it reads UUID of that
array. Then it scans for /dev/sd* partitions and checks with "mdadm --examine"
if UUID matches. If so, the partition can be added with "mdadm --add". That is
why I asked abut this feature in mdadm - recognising if there is a new partition
belonging to monitored array. With mdadm this procedure would work on elegant
manner.
udev really is the right way to do this. Just get udev to run
mdadm -I /dev/newdev
whenever a device is discovered. It can then be automatically re-added
depending on the policy set up in mdadm.conf.
"mdadm --monitor" will not gain this functionality. It is for monitoring
active arrays, not for monitor new devices.
NeilBrown
Yes, that ist what I need and what I asked for!: udev + mdadm -I
I didn't know the Incremental function of mdadm (mea culpa). And udev is even
prepared for this! (at least in Ubuntu)
I never thougt it is so simple!
thank You
For another people looking for similar solution I write what I did:
1.
I switched /etc/udev/udev.conf/udev_log to "debug" to see what happen after
inserting new drive.
2.
After inserting the drive I found in logs following lines:
Aug 22 11:08:47 serwer-linmot udevd[2287]: '/sbin/mdadm --incremental
/dev/sdc3'(err) 'mdadm: not adding /dev/sdc3 to active array (without --run)
/dev/md/0'
Aug 22 11:08:47 serwer-linmot udevd[2287]: '/sbin/mdadm --incremental /dev/sdc3'
[2310] exit with return code 2
3.
In Ubuntu there is in /lib/udev/rules.d/64-md-raid.rules file responsible for
this. I only changed one line:
ACTION=="add", RUN+="/sbin/mdadm --incremental $tempnode"
to:
ACTION=="add", RUN+="/sbin/mdadm --incremental --run $tempnode"
And thats all!
Now, I don't have to use my script from crontab anymore. Raid start rebuilding
array immediately after disk is inserted.
Sergiusz
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