Mogile Deployment Layout: More Hosts or More Disks.

[Javier Frias]

Hello all,

At my company we've recently evaluated mogilefs and it seems to meet
our needs. (great piece of software btw ) We are now planning to build
out our prod configuration and are having issues deciding on a
hardware layout, so I'm looking for input from people that may have
used mogilefs in a similar way.

Basically, we will be using mogilefs for long term text and image
archiving, as well as low level image serving ( it will only be
feeding our CDN, so while there will be some performance issues, it
doesnt look to be now our primary concern since the system will only
be feeding the CDN and not taking the brunt of the traffic itself ),
but from time to time, we will run batch jobs that will fetch ten's of
thousands of items for reprocessing.

Main question is, do we do more hosts per disks, or more disks per hosts.

Due to hardware standards ( self imposed, too many hosts to have to
worry about yet another hardware manufacturer ) I have the choice of
either a host that can handle two 750GB disks ( dell 860s or 1435's )
or a host that can handle 6 x 750GB disks ( dell 2950's ) for the
storage nodes. The difference in pricing is about 20%  in favor of a 6
disk server solution, versus a 2 disks server solution. So is the
extra complexity worth it in terms of performance and redundancy? or
will i be shooting myself in the foot by having 3 X the number of
storage nodes? I'm planning a 3 copy policy for most of my files, and
will need approximate 5TB to start, so we are taking of at least 4 x 6
disks systems, or 10-12 2 disk systems.

Any input greatly appreciated.

As a side note, any real reason not to run the trackers on the storage
nodes? also, anyone have any pros cons on running mysql master/save
with InnoDB on DRBD versus running lets say mysql cluster?


thx