Hi All,
I am setting up a Dell PowerEdge 850 with FC4 (customer's app requires it).
It has 2GB of RAM, 3.2GHZ Pentium 4 and a PERC 4/SC (aka megaraid)
raid controller with two seagate SCSI-3 300GB 10,000RPM drives.
I have configured the logical drive as RAID 1 (mirroring) with the defaults for
for a logical drive 0 - StripeSize 64K, Write Policy = Write Through, Read
Policy = Adaptive, Cache Policy = DirectIO.
I have a 250GB partition (per customer's request). When I run
hdparm -t -T on the device I get ~2408MB/sec on cached reads.
On buffered disk reads I get ~35MB/sec which seems awfully slow
given the h/w. I'm running the system in single user mode to eliminate
background processes.
My buffered reads will start at 50MB/sec and after ~8-10 iterations drops
to ~35 MB/sec.
For a test I installed FC5 and there buffered reads were around ~75MB to
start with and after ~8-10 iterations dropped to ~39MB/sec.
Can anyone shed any light on why the i/o appears so slow? On 7500 RPM
SATA with drives I get buffered reads of around ~60-70MB.
I've tried changing parameters in the PERC controller screen but nothing seems
to work.
Any insight appreciated!
Mike
Also the kernel driver being used is megaraid_mbox.
Mike
