Distributed
Scratch Space
Date: 1/13/2003
A distributed scratch space is now available on a test basis
on all HPCC systems (SGI, Sun, IBM Linux).
This distributed
scratch filesystem is mounted as /dscratch on all systems.
Since
it is distributed you can see files in /dscratch as they are
written on a remote (non-interactive) system. Users may also
utilize this filesystem from any of the interactive systems
(perseus, sun1, stats).
The current
local /scratch filesystem will continue to be available on
all systems.
Data stored
to this filesystem will not be backed up. See "Additional
Details" below.
Should
you encounter any problems or have additional questions please
send email to hpcc@nd.edu.
Sincerely,
ND HPCC
Administrators
Additional
Details:
The /dscratch filesystem consists of twenty-four 73 GB fibre
channel disk drives in an IBM FAStT500 Storage Server. The
FAStT500 has a single dedicated hardware RAID controller with
512 MB of memory cache. In the RAID 0+1 configuration the
drives are striped and mirrored together for the best performance
and reliability.
800 GB
of disk space are available for use by HPCC users in this
filesystem.
For distributing
the /dscratch filesystem to the HPCC systems, a dedicated
high performance gigabit(Gb) network is used (except for the
stats machine which uses it's 100 Mb interface). The SGI and
IBM Linux systems use jumbo frames (9000 byte packets), these
larger packet
sizes significantly reduce the overhead in moving data. While
data on this filesytem is not backed up it is highly reliable
due to the disk mirroring. Half of the 24 drives are used
for a real time mirror (copy) of the filesystem.
Currently
there is no disk quota policy enforced on the /dscratch filesystem.
The disk cleanup policy will be the same as the other HPCC
temporary filesystems (/tmp, /scratch). The policy is that
Gaussian files not modified or accessed in the past 15 days
are removed. Other files not modified or accessed in over
60 days will be deleted.
created
1/13/03
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