Harmen harmen at
Tue Mar 15 04:21:04 PST 2005

On Mon, Mar 14, 2005 at 04:40:16PM -0800, Mark Smith wrote:
> > what to do if a content server explodes? Is there a script to restore the
> > poor system using the other hosts?
> Well, MogileFS is designed to have multiple content servers.  Every file
> has a minimum replica count which specifies how many servers it has to be
> on, and so it's replicated across that many machines.
> If a machine implodes, all files should be available from another machine.
> So, you'd then mark a machine as 'dead' in the database, allocate a new
> machine, new device ids, and files would be automatically replicated to the
> new machine.

Ok. Does the copying happen the moment the new machine is added? Or only
once a file is requested and the tracker notices it's missing?
What if one of the content servers is down for a short while? Will the trackers
somehow monitor this and copy all pending data to it when the content
server is available again?

> > Is there a (theoretical) way to replace the mysql dbase by something less,
> > well, dbase like? What do you use with livejournal for the tracker? Some master-master
> > setup?
> Right now, we point the MySQL host at one machine, and then we have a spare
> machine as a slave doing nothing but replicating and keeping a copy of the
> SQL database.  We also frequently back this data up to our backup array.

But it requires a select for each and every request, right? Or does it get
chached in memory somehow?

Thanks again for all the help,


                               The Moon is Waxing Crescent (28% of Full)

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