At 08:28 PM 1/9/2006, Brian D. Ropers-Huilman wrote:
Simple question, likely a complicated answer. Cluster systems should have up
to three distinct file systems:
1) a place to compile and keep "stuff"
2) a bit of disk to use while code is running
3) potential a bit of disk with special characteristics, likely
high-performance
Typically #1 would be called /home. Here at LSU, #2 is typically called
/var/scratch or /var/local/scratch. Then there is #3. Sometimes we call this
/scratch and sometimes /work.
My question: what do other folks call these bits of disk?
Our /home is the place for #1. If users/admins have specific programs
that they want to make publically available, it can be published
under admin-supervision in /usr/local. Given the number of nodes we
have relative to network performance, and the potential aggregate
bandwidth problem to the central server, it is not intended for any
scratch file storage for running jobs, only for "real" data.
For small, non-bandwidth-sensitive local scratch (#2), we just use
/tmp, local on each node. Small means there is at least 4GB available
(up to 30GB on some nodes), but on a regular local disk.
Nodes designed for IO-intensive calculations have a /tmpfast
filesystem where a raid-0 array is mounted (#3). Sizes are large (as
large as needed for our current computational problem), throughput is
high (such that IO/CPU bottlenecks are reasonably balanced for our
typical problem sizes). If these nodes are used for non-IO-intensive
jobs, it is nonetheless recommended to move regular scratch files
(usually /tmp) to /tmpfast. A simple scripted check for the existance
of this filesystem is sufficient and easy to implement to achieve this.
Our calculational needs do not include the permanent storage of very
large datafiles, only large scratch files that are discarded after
job completion.
Luc Vereecken
Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm
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