This is informative. Comparing Rsync vs Rsyncd, which has less load on the
client side? I'm considering moving away from my implementation rsync via
autofs cifs.
Kris Lou
k...@themusiclink.net
On Fri, Oct 29, 2010 at 8:25 AM, Les Mikesell <lesmikes...@gmail.com> wrote:
> On 10/29/2010 8:16 AM, Richard Shaw wrote:
> > There is surprisingly little info on how BackupPC really works, at
> > least with the google searches I've tried. I'm just looking for a
> > concise overview of how the different backup methods work and how they
> > are different from one another.
> >
> > The reason I'm looking for this information is I will be giving a
> > presentation of BackupPC to my local LUG.
> >
> > I'm looking for something as close as I can get to:
> >
> > Rsync:
> > 1. BackupPC does x.
> > 2. Then this.
> > 3. Then this.
> > 4. etc.
> >
> > Rsyncd:
> > 1. Same as rsync except x.
> >
> > Tar:
> > ...
> >
> > Smb:
> > ...
> >
> > and so forth.
>
> First backuppc uses a native tool to transfer files. Then it checks the
> file contents against the pool with a hashing mechanism, and replaces
> any exact matches with a link to the existing pool copy.
>
> > For instance: I can understand how tar over SSH transfers files. But
> > who decides what files to transfer?
>
> Your file include or exclude lists are mapped into the options
> appropriate for the xfer program with the 'share' as the top of the tree.
>
> > Does BackupPC crawl the share
> > first and build a filelist? Or is there an option for tar that takes
> > care of if for BackupPC?
>
> With tar and smb, backuppc doesn't know much about the remote side - it
> just passes the options to the program. Tar runs over ssh entirely on
> the remote side.
>
> > For SMB I understand that it would just look like a local filesystem
> > after the share is mapped to the BackupPC server. Then what? Does it
> > use rsync against the network share?
>
> The smb method actually uses the smbtar program so it looks more like
> tar than a mapped file system.
>
> The rsync method runs a native rsync via ssh on the remote side, using a
> perl implementation on the server. Rsyncd is similar, but talks to a
> standalone rsync running in daemon mode that must be set up on the
> target. Rsync sends the entire directory tree you request from the
> remote, then both sides walk the list to find and send differences.
>
> The practical difference is that rsync uses less bandwidth and is better
> at catching every change in incrementals. The smb and tar methods go
> strictly by file timestamps and will miss moved or copied files that
> keep their old timestamps, where rsync will find them with the directory
> comparison against your previous full tree.
>
> --
> Les Mikesell
> lesmikes...@gmail.com
>
>
>
>
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------------------------------------------------------------------------------
Nokia and AT&T present the 2010 Calling All Innovators-North America contest
Create new apps & games for the Nokia N8 for consumers in U.S. and Canada
$10 million total in prizes - $4M cash, 500 devices, nearly $6M in marketing
Develop with Nokia Qt SDK, Web Runtime, or Java and Publish to Ovi Store
http://p.sf.net/sfu/nokia-dev2dev
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