Gentlemen,
thanks to
Dr. Tom Blinn, 603-884-0646" <tpb_at_doctor.zk3.dec.com>
John J. Francini <francini_at_zk3.dec.com>
Both suggested that the problem was a file fragmentation issue.
Original Problem:
On a hsg80 6way raid10 devices:
Sequential read performance for files that have been created in parallel
is only about 20mb/sec while sequential reads for files that have been
created serially is about 50mb/sec
Satement:
The IO was taking place on an AdvFS. The AdvFS is an extent based file
system and fragments the files written in parallel. While reading
the disks need to perform more head movements thus decreasing IO throuput.
To veryfy this i run the "defragment" application on the appropriate file
domain. This indeed completely solved all trouble :)
--Armin
Received on Mon Nov 20 2000 - 14:42:53 NZDT