On running daily lvm snapshot backups via vzdump on OpenVZ servers, I noticed the below Kernel errors in logwatch reports.

WARNING:  Kernel Errors Present
Buffer I/O error on device dm-4,  ...:  22 Time(s)
EXT3-fs error (device dm-4): e ...:  60 Time(s)
lost page write due to I/O error on dm-4 ...:  22 Time(s)

This would show up on busy servers only, probably caused due to lvm snapshot running out of space.

I edited “/usr/bin/vzdump” and increased the size from 500m to 1000m which seems to have resolved the issue for now.

run_command (\*LOG, "$lvcreate --size 1000m --snapshot --name vzsnap /dev/$lvmvg/$lvmlv");