[ceph-users] Re: HBA vs caching Raid controller

For the background: we have many Perc H800+MD1200 [1] systems running with 10TB HDDs (raid0, read ahead, writeback cache). One server has LSI SAS3008 [0] instead of the Perc H800, which comes with 512MB RAM + BBU. On most servers latencies are around 4-12ms (average 6ms), on the system with the LSI controller we see 20-60ms (average 30ms) latency.

How did you get these latencies? Then I can show you maybe what I have with the SAS2308.