dan wrote:
> 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

Since he is only copying one backup run there probably won't be any hard 
links within the run and cp/rsync won't know or care about links to the 
pool.  What you really need here is to make a tree of hardlinks instead 
of a copy but I don't think any standard tools do that.  But, you are 
going to remove the extra copy as soon as a new full run completes so 
the space probably doesn't matter. The only place I think it might go 
wrong is if backuppc hard-links matching files in the next run to the 
copy from the previous instead of the hash match in the pool.  If that's 
the case you will end up with files that persist under each PC's 
directories but never end up linked to the pool and thus to each other.


> 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?

Rsync should just send the attributes that need to be changed.  Backuppc 
will pool the files based only on contents, since it keeps the 
attributes separately and they aren't required to be the same on all copies.

-- 
   Les Mikesell
    lesmikesell AT gmail DOT com

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