just want to clarify here.

you have x number of remote hosts, all running the same OS and presumably have almost identical files (size, permissions etc)? and you want back one up and then clone that backup for each of the other machines to avoid transfering the data numerous times?

you should add the -H flag to cp or rsync to take hardlinks with:

rsync -aH /var/lib/backuppc/pc/host1/0 /var/lib/backuppc/pc/host2/0
cp -aH /var/lib/backuppc/pc/host1/0 /var/lib/backuppc/pc/host2/0

This should help you reduce the initial transfer cost in bandwidth but the remote systems wont have the same mtime so you wont be able to keep just one copy of the file on the backuppc server hardlinked across all of the similar hosts AFAIK.  rsync will only want to change the timestamp but will create a new file in the pool because the files are not identical because the times are different.

someone please correct me if this is incorrect.  will rsync run an md4 on the file and consider it identical reguardless of the time?

As a workaround, you might make a list of files on the template system including mtime and then write a script to crawl through each of the other machines filesystems and use touch to alter the mtime to match the first machine.  That way rsync will see them as identical.  Generally speaking, if the machine times are the same, altering the mtime of the files wouldnt have any adverse effects.

good luck!

On Sun, Jan 18, 2009 at 2:01 PM, Matthias Meyer <matthias.meyer AT gmx DOT li> wrote:

I plan to backup (with rsync) some machines with nearly identical data
(operating system). Because this machines are only reachable through
internet I want to avoid a lot of traffic for files which are already
on the backuppc server.
I assume rsync will only compare the data between the client and the
backup of the client and not between client and cpool!?

So my idea:
0) create host1 with the backuppc gui
1) host1 runs a full backup
2) create host2 with the backuppc gui
3) cp -a /var/lib/backuppc/pc/host1/0 /var/lib/backuppc/pc/host2/0
4) cp -a /var/lib/backuppc/pc/host1/backups /var/lib/backuppc/pc/host2/backups
5) run a full backup for host2
6) run BackupPC_deleteBackup -c host2 -d 0

Someone believe that this will make a problem?
If somebody is interested I can make a script
(similiar the BackupPC_deleteBackup) and store it in the wiki.

br
Matthias
--
Don't Panic


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