[Beowulf] Newbie Question: Racks versus boxes and good rack solutions for commodity hardware

Mark Hahn hahn at mcmaster.ca
Fri Dec 12 19:20:57 PST 2008

> What is 1u?

rack-mounted hardware is measured in units called "units" ;)
1U means 1 rack unit: roughly 19" wide and 1.75" high.  racks are all
the same width, and rackmount unit consumes some number of units in height.
(rack depth is moderately variable.)  (a full rack is generally 42").

a 1U server is a basic cluster building block - pretty well suited,
since it's not much taller than a disk, and fits a motherboard pretty 
nicely (clearance for dimms if designed properly, a couple optional 
cards, passive CPU heatsinks.)

> What is a blade system?

it is a computer design that emphasizes an enclosure and fastening mechanism
that firmly locks buyers into a particular vendor's high-margin line ;)

in theory, the idea is to factor a traditional server into separate
components, such as shared power supply, unified management, and often
some semi-integrated network/san infrastructure.  one of the main original
selling points was power management: that a blade enclosure would have
fewer, more fully loaded, more efficnet PSUs.  and/or more reliable. 
blades are often claimed to have superior managability.  both of these 
factors are very, very arguable, since it's now routine for 1U servers 
to have nearly the same PSU efficiency, for instance.  and in reality, 
simple managability interfaces like IPMI are far better (scalably scriptable)
than a too-smart gui per enclosure, especially if you have 100 enclosures...

> goes into a good rack in terms of size and matieral (assuming it has to be
> insulated)

ignoring proprietary crap, MB sizes are quite standardized.  and since 
10 million random computer shops put them together, they're incredibly
forgiving when it comes to mounting, etc.  I'd recommend just glue-gunning
stuff into place, and not worring too much.

> Anyone using clusters for animation on this list?

not much, I think.  this list is mainly "using commodity clusters 
to do stuff fairly reminiscent of traditional scientific supercomputing".

animation is, in HPC terms, embarassingly parallel and often quite
IO-intensive.  both those are somewhat derogatory.  all you need to do
an animation farm is some storage, a network, nodes and probably a 
scheduler or at least task queue-er.

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