Hello,
We are testing the following setup:
- LSI SAS3442X controller
- Promise J300S SAS JBOD connected via the external port of the SAS
controller
- 10 SATA disks (Seagate) in the JBOD
- Linux kernel 2.6.16RC2 on a INTEL Dual Xeon Server, 2.8 Ghz, 64 bit mode
LSI SAS driver provided by the kernel finds the JBOD and the disks.
Single disk performance is like attaching via a SATA controller from the
chipset.
Testing with multiple parallel drive accesses gives very poor results
and high system utilisation.
Tests performed with parallel invocations of dd with bs=32k. Values in MB/s.
# of disks READ AVG WRITE AVG
1 60 60,0 58 58,0
5 310 62,0 288 57,6
6 344 57,3 336 56,0
7 259 37,0 375 53,6
8 226 28,3 391 48,9
9 245 27,2 402 44,7
10 265 26,5 405 40,5
Up to 5 drives it looks as it should. Then the performance goes
significantly down for READ operations.
The card is plugged in a 100 MHz PCI-X slot. No other activity on the
system.
Any hint?
Thanks,
Mirko
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