From: James M. Craw (craw_at_nersc.gov)
Date: 09/16/2004
NERSC Users: A quick update on Seaborg's degraded I/O performance (for some operations). Since earlier this week, NERSC and IBM have been working around the clock together to find the root cause of the I/O slowness. We believe we have found a major reason for the slowness in the "ml0" code. This code "load balances" switch communication across each node's two css adapters. An initial fix was generated last night and tested on a IBM test system, the NERSC development system and on a few nodes of Seaborg today successfully. The E-fix was then pushed out across the entire system early this afternoon. Tests to date, show positive results. Additional testing will continue through the night. Users are encouraged to run their normal applications that can stress the GPFS filesystems (scratch and homes). As always, please report any problems to the NERSC consulting staff at consult@nersc.gov as soon as you can. Thank you, again, for your patience. Jim Craw NERSC Computational Systems Group Leader
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