PowerEdge MegaRaid Linux large files

Ron Stanonik stanonik at Cogsci.ucsd.edu
Tue Aug 28 13:13:00 CDT 2001


We bought a PowerEdge 6300 (year or two ago) with 1GB RAM,
six 18GB disks, PERC2/SC (megaraid), and RedHat (6.X at the
time, 7.1 now).

The six disks were configured as one raid 5.

If anyone writes a large file, any other writes hang until the
large file finishes.  Since almost any activity creates files
(email, /tmp, utmp, etc), all activity hangs until the large
file finishes.  Of course the large file must be really large
(>100GB) for the hang to be noticeable, but for us this happens
often enough to be a problem.

We've flashed the latest megaraid BIOS (3.13) and are running
the (almost) latest megaraid driver (kernel 2.4.8, driver 1.17).

If we configure the six disks as one raid 0, then the problem doesn't
occur.  Bummer, we'd really like the protection of raid 5.

We keep hoping that the next BIOS update or kernel version or driver
version will fix it, but not yet.

Wondering if you've encountered this, have any hints, etc.


Ron Stanonik
stanonik at cogsci.ucsd.edu

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