On Wed, 11 May 2011 14:32:56 -0400, Jeffrey J. Kosowsky wrote:

> How big was your pool and pc tree?

 We currently have two BackupPC servers we work with -- one of them is 
 only about 20G of disk but is using a silly number of inodes (it's 
 backing up a maildir mail server, among other things), and I think the 
 other is around 3 or 4 TB of disk used at the moment. I don't remember 
 which one we had to move, it happened about a year ago. The best I can 
 recall is that we struggled with rsync for a week or so, then I found 
 out about tarpipes and that got the job done overnight.

 You're right though, on second look, it looks like rsync -a should work 
 just as well as tar. I'll have to do another BackupPC pool transfer in a 
 few days, and now I'm curious what (if any) difference there is between 
 tar and rsync, so I'll try both.

 - R.

> The problem is not really a rsync-specific one but rather is due to
> the huge number of hard links that must be tracked and cached which
> both consumes an increasing amount of memory and also potentially cpu
> power to sort/find the right link...
> The bottom line is that if you are using a "generic" program like
> rsync or tar that doesn't understand the special structure of the 
> pool
> and pc hierarchies then essentially the inode and path of each pool
> file must be cached and referenced when copying the archive. This 
> does
> not scale well as many if not all people have found.
>
> I can believe though that tar might work ok on small archives (just
> like rsync can)...

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 [__ Founder, No Problem
 [__ Information technology support and services
 [__ (530) 575-0278
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