Exclusive file access while doing backup?

Question

Hello!
I am hosting a minecraft server on my old 900MhZ homeserver [it DOES run really well, arch is doing an amazing job ] and I made a little bash script to daily backup the current savegame, which I run via cron:
#!/bin/bash
MC_PATH="/home/tom/mc_bukkit/dasiro"
BKP_PATH=/home/tom/_backup
if [ -d "$MC_PATH" ]; then
filename=minecraftsave_`date "+%Y-%m-%d_%H-%M-%S"`.tar.xz
tar --create --xz --file $BKP_PATH/$filename $MC_PATH
find $BKP_PATH -name "minecraftsave*" -mtime +14 | xargs rm
fi
The problem is that most often it is run I get tar: ./mc_bukkit/dasiro/region/r.-1.0.mcr: file changed as we read it.
Is it possible to "lock" the file for a few seconds while the backup is run? Maybe there is a possibility... It is no problem if the server "freezes" for a few seconds. Thank you!
Last edited by cyberius (2011-05-14 08:03:03)

Answer 1

Take a look at lvm and specifically lvmsnapshots.
If you have the files you wish to backup on a lvm partition, then you can create a lvm snapshot, which is a frozen snapshot of the partition. The original partition is untouched and goes about it's business.  You can then mount the snapshot like any other filesystem and make a backup of it's contents.