John Goerzen wrote:
>
> First off, I gather that it keeps a hardlinked pool of data, so
> whenever a file changes on any host, on the backup device, it will be
> hardlinked to a file containing the same data, regardless of the host
> it came from, right?
>
> So, given that, I don't really understand why there is a distinction
> between a full and an incremental backup. Shouldn't either one take
> up the same amount of space? That is, if you've got few changes on
> the client, then on the server you're mostly just hardlinking things
> anyway, right? So why is there a choice?
With the tar and smb backup methods, full runs transfer everything from
the remote, incrementals transfer only files with timestamps newer than
the last full. With rsync, a full does a block checksum compare of all
files, incrementals only files where the timestamp or length differ. On
the server side, fulls rebuild a complete tree of links, incrementals
only have the differing files.
> Secondly, I gather that BackupPC mangles filenames. That doesn't
> bother me, but how is it possible to use rsync in an efficient way
> with that? rsync wouldn't be able to match up client-side filenames
> with the server-side names since the server names are different, so it
> wouldn't do its efficient transfers. Either that or you're having to
> create temporary directory trees on the server, which sounds
> inefficient. Or am I missing something?
The server doesn't run the stock version of rsync. It has a perl
version that understands the filename and compression conventions it
uses for storage and can work with a stock rsync on the remote side.
--
Les Mikesell
[email protected]
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