Remount root RW without reboot

ext4filesystemsmount

Today I did something stupid on production xen vm server. I mounted the external device mapper as read only to make a copy of the filesystem. This process went well but then the rootfs / become read-only inside the guest machine.

/dev/xvda on / type ext4 (ro,relatime,errors=remount-ro,user_xattr,barrier=1,data=ordered)

Fortunately all the important services on it using the /home and /var partitions so the machine won't stop functioning but now I cannot remount the /root as RW without rebooting it (which is not an option since it's production).

I tried:

  1. fsck -f /dev/xvda
  2. mount -o rw,remount /
  3. mount -n -o remount,rw /

It does not allow to remount it as RW.

[Mon Jul  7 14:59:06 2014] EXT4-fs error (device xvda): ext4_remount:4558: Abort forced by user
[Mon Jul  7 14:59:21 2014] EXT4-fs error (device xvda): ext4_remount:4558: Abort forced by user
[Mon Jul  7 14:59:50 2014] EXT4-fs error (device xvda): ext4_remount:4558: Abort forced by user
[Mon Jul  7 15:00:13 2014] EXT4-fs error (device xvda): ext4_remount:4558: Abort forced by user
[Mon Jul  7 15:00:16 2014] EXT4-fs error (device xvda): ext4_remount:4558: Abort forced by user

Please tell me is it possible without reboot?

Best Answer

I've used mount -o rw,remount / without problems many times. The "Abort forced by user" message indicates there may be a problem with the filesystem, which can only be fixed with an fsck. Unfortunately, you'll probably have to reboot to do this. Another alternative is that the disk is a USB or flash device with a physical read-only toggle, which needs to be flipped.

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