Scope
This article explains the cause and solution for a "No bootable medium" error message on screenshot verification or when trying to virtualize a Linux recovery point.
Cause
This is caused by a Linux kernel bug documented here: https://bugzilla.redhat.com/show_bug.cgi?id=1250717
This bug causes the ext4 filesystem driver to mount an ext2 partition. When this happens, freezing and unfreezing the filesystem causes the blkid to lose the ext2 volume. Since the Datto Linux driver freezes each filesystem when taking a backup snapshot, this kernel bug is triggered.
Solution
If you're having this problem with a Ubuntu 14.04 install, you can upgrade to 14.04.5, which has a 4.4.0 kernel that has the fix in it.
Alternatively, update your /boot volume (or whatever volume is formatted to ext2) to ext3. By adding the journal ext3 provides, the bug is avoided. Here's the procedure to do that:
1) List the mounted devices and filesytem types: df -hT
You'll see something like this:
Filesystem Type Size Used Avail Use% Mounted on udev devtmpfs 990M 0 990M 0% /dev tmpfs tmpfs 201M 4.9M 196M 3% /run /dev/sda3 ext4 27G 3.8G 22G 15% / tmpfs tmpfs 1001M 80K 1001M 1% /dev/shm tmpfs tmpfs 5.0M 0 5.0M 0% /run/lock tmpfs tmpfs 1001M 0 1001M 0% /sys/fs/cgroup cgmfs tmpfs 100K 0 100K 0% /run/cgmanager/fs tmpfs tmpfs 201M 44K 201M 1% /run/user/1000 /dev/sda1 ext2 2.7G 43M 2.6G 2% /boot
Take note of the device name (/dev/sda1
) and the mountpoint (/boot
) for the ext2 volume, that's the one we need to fix.
2) Unmount the ext2 partition, in my example, /bootumount /boot
If you can not unmount it because it's in use and can't be freed, you must perform this procedure from a live boot disk.
3) Add the journal to the ext2 filesystem, making it ext3 compatible:tune2fs -j /dev/sda1
4) Edit /etc/fstab
change the mount instructions to use ext3. Look for the ext2 reference in /etc/fstab
and change it to ext3
.
5) Remount the updated filesystem:mount /boot
At this point you should see the filesystem mounted as ext3.
6) Run df -hT
again:
Filesystem Type Size Used Avail Use% Mounted on udev devtmpfs 990M 0 990M 0% /dev tmpfs tmpfs 201M 4.9M 196M 3% /run /dev/sda3 ext4 27G 3.8G 22G 15% / tmpfs tmpfs 1001M 80K 1001M 1% /dev/shm tmpfs tmpfs 5.0M 0 5.0M 0% /run/lock tmpfs tmpfs 1001M 0 1001M 0% /sys/fs/cgroup cgmfs tmpfs 100K 0 100K 0% /run/cgmanager/fs tmpfs tmpfs 201M 44K 201M 1% /run/user/1000 /dev/sda1 ext3 2.7G 43M 2.6G 2% /boot
You can see /boot is now mounted as ext3.
You should have no more problems backing up this volume.
Head on over to our Datto Community Forum or the Datto Community Online.
For more Business Management resources, see the Datto RMM Online Help and the Autotask PSA Online Help .
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