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Why am I unable to create LVM snapshots during a backup?

Why am I unable to create LVM snapshots during a backup?

I have configured my backups to use the LVM snapshot feature, but I get the error:
Logical volume "[lvname]" already exists in volume group "[vgname]".
Due to this error, the active logical volume will be backed up instead.


ANSWER

Systems that use both LVM2 and UDEV may run into this issue. Both LVM2 and UDEV create the device nodes for the snapshot logical volumes. However, there is a conflict because the "lvremove" command only removes what LVM2 created and not what UDEV created. So the next time SBAdmin creates the snapshot, it appears the device is in use. You can correct this my changing a line in the /etc/udev/rules.d/50-udev.rules file.

Replace

KERNEL=="dm-[0-9]*", ACTION=="add", PROGRAM="/sbin/udev.devmap_name.sh %M %m", NAME="mapper/%c"

with

KERNEL=="dm-[0-9]*", OPTIONS+="ignore_device"

This should prevent the conflicts.