Wed Apr 11 17:58:22 CDT 2012
latency. At 10s and up, latency jumps to multiple *seconds* and
throughput drops to "zero". This clearly shows that when cache is full
and must flush, the drives are simply overwhelmed. 10x 7.2k striped
SATA spindles would not perform this badly. Thus it seems clear your
LUN sits on only 4 of the 12 spindles.
The cached performance of the P2000 is about 50% of the LSI, and the LSI
has 4x less cache memory. This could be due to cache mirroring between
the two controllers eating 50% of the cache RAM bandwidth.
So in summary, it would be nice to know the disk config of the LSI.
Once we have complete hardware information, it may likely turn out that
the bulk of the performance differences simply come down to what disks
are attached to each controller. BTW, you provided lspci output of the
chip on the RAID card. Please provide the actual model# of the LSI
card. Dozens of LSI and OEM cards on the market have used the SAS1078
ASIC. The card you have may not even be an LSI card, or may even be
embedded. We can't tell from the info given.
The devil is always in the details Stefan. ;)
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