[mirror-admin] push mirroring plans

[Chuck Anderson]

On Wed, Dec 17, 2008 at 10:05:53AM -0800, Jesse Keating wrote:
> On Tue, 2008-12-16 at 22:17 -0600, Matt_Domsch at Dell.com wrote:
> > Thoughts?
> 
> Why not something far far more simple, which is a site checksum.  Each
> time we put new content on the site, we update a checksum (it doesn't
> have to be an /actual/ checksum, just some int we increase).  Mirrors
> can more frequently stat the value of this checksum against what they
> have, and if it changes, they know to do a full rsync run.  If it
> doesn't change, they don't do an rsync run.
> 
> This would allow mirrors to ramp up their polling of us to every 10
> minutes or even less, without worry of swamping our server with stats of
> files.  Any other solution is going to be "polling" in some form or
> another, either a daemon listening for an ssh push, or a email server
> waiting for mail to come in.  This more simple method doesn't rely on
> the setup of additional infrastructure on the mirror side, just a slight
> adjustment to the cron jobs mirrors already have in place.  If we make
> the file available via rsync at a top level, or even different files at
> different logical sections of the master mirror it would be quite
> simple.

See my other email in this thread about what is essentially a 
"TIMESTAMP" file.  The issue I see with this is that unless mirror 
admins are very careful to update the checksum/timestamp file 
separately after a regular sync is complete, we can end up with a 
situation where a downstream mirror thinks version X is up and ready 
but in reality it is only partially synced.  Everybody should be using 
--delay-updates, but...

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