That brings me to another important question. Any hints on speccing
the head-node?
I think you imply a single, central admin/master/head node. this is
a very bad idea. first, it's generally a bad idea to have users on
a fileserver. next, it's best to keep cluster-infrastructure
(monitoring, management, pxe, scheduling) on a dedicated admin machine.
for 300 compute nodes, it might be a good idea to provide more than
one login node (for editing, compilation, etc).
Especially the kind of storage I put in on the head
node. I need around 1 Terabyte of storage. In the past I've uses
RAID5+SAS in the server.
1 TB is, I assume you know, half a disk these days (ie, trivial).
for a 300-node cluster, I'd configure at least 10x and probably
100x that much. (my user community is pretty diverse, though,
and with a wide range of IO habits.)
Mostly for running jobs that access their I/O
via files stored centrally.
it would be wise to get some sort of estimates of the actual numbers -
even the total size of all files accessed by a job and its average
runtime would let you figure an average data rate.
For muscle I was thinking of a Nehalem E5520 with 16 GB RAM. Should I
I don't think I'd use such a nice machine for any of fileserver, admin or
login nodes. for admin, it's not needed. for login it'll be unused a lot of
the time. for fileservers, you want to sweat the IO system, not the CPU
or memory.
boost the RAM up? Or any other comments. It is tricky to spec the
central node.
spec'ing a single one may be, but a single one is a bad idea...
Or is it more advisable to go for storage-box external to the server
for NFS-stores and then figure out a fast way of connecting it to the
server. Fiber perhaps?
10G (Cu or SiO2, doesn't matter) is the right choice
for an otherwise-gigabit cluster.
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