Linux – Software RAID unmount before shutdown

centoslinuxsoftware-raid

I have my mysql directory /var/lib/mysql mounted in /dev/md0.
When I shutdown/reboot my server, the system fails to switch the md0 in read-only mode because devices are busy, obviously by mysql.

During the startup, it causes some delay because of error scan and the drives are not mounted before the system try to reassemble the RAID array and mount it.

I need to service mysqld stop, umount /dev/md0, then mdadm –stop /dev/md0, so the server will shutdown cleanly and restart without any problems.

Is it the standard procedure when there's a software raid or the system should have been able to do it by itself ? Is there a way to do those steps automatically before a shutdown/reboot ?

Thanks for your help !

Best Answer

The init system should shut down mysqld. Do you have a /etc/rc.d/rc0.d/K*mysqld and /etc/rc.d/rc6.d/K*mysqld? Did you install mysql-server from an RPM?

Related Solutions

Centos – mdadm set the mode before a second device raid1

ok im found problem. right command :

mdadm /dev/md0 -a /dev/sda1

not :

mdadm –manage /dev/md0 –add /dev/sda1

and finally working on !

root@rescue ~ # cat /proc/mdstat
Personalities : [raid1]
md3 : active raid1 sda5[3] sdb5[2]
      1847605568 blocks super 1.0 [2/1] [_U]
        resync=DELAYED

md2 : active raid1 sda3[3] sdb3[2]
      1073741632 blocks super 1.0 [2/1] [_U]
      [>....................]  recovery =  4.8% (52262208/1073741632) finish=88.1min speed=193162K/sec

md1 : active raid1 sda2[3] sdb2[2]
      524224 blocks super 1.0 [2/2] [UU]

md0 : active raid1 sda1[3] sdb1[2]
      8388544 blocks super 1.0 [2/2] [UU]

unused devices: <none>

Linux – Ubuntu 14.04 Software RAID 1 – md0 inactive

You've got a rather perplexing system there. /dev/sdb (the entire volume) and /dev/sdb1 (the first partition on that volume) are both being detected as RAID devices. This is confusing the OS, and it's creating two RAID arrays: /dev/md0 is a degraded RAID 1 array consisting of /dev/sdb, and /dev/md127 is a degraded RAID 1 array consisting of /dev/sda1. Since they're degraded, the OS won't automatically start them.

The first step in recovering from this is to make a volume-level backup (dd if=/dev/sda, dd if=/dev/sdb), so that if things go wrong, you won't be any worse off than you currently are.

Once you've done that, you can activate your arrays in read-only mode: mdadm --run --readonly /dev/md0; mdadm --run --readonly /dev/md127, mount the disks, and see what each contains.

Assuming that you're correct that /dev/sdb is the RAID array you're using, the next step is to figure out what it was using as the second volume of the RAID array: the metadata clearly states that when you shut it down, it was a two-disk RAID 1 array with both disks present.

If you can't figure it out, or don't want to use whatever the missing piece is, and you're correct that /dev/sda1 contains nothing important, the next step is to add it to /dev/md0:

Wipe out the partition table and md metadata as a safety precaution: dd if=/dev/zero of=/dev/sda bs=1M count=1024
Add it to the array: mdadm --manage /dev/md0 --add /dev/sda and let the array rebuild.

The final step is to wipe out the md superblock on /dev/sdb1. According to the mdadm man page, mdadm --zero-superblock /dev/sdb1 will work, but since the superblock is inside an existing array, I'd be very nervous about actually doing this.

Best Answer

Related Solutions

Centos – mdadm set the mode before a second device raid1

Linux – Ubuntu 14.04 Software RAID 1 – md0 inactive

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