major performance drop on raid5 due to context switches caused by small max_hw_sectors

2007-04-20 Thread Pallai Roland
Hi! I made a software RAID5 array from 8 disks top on a HPT2320 card driven by hpt's driver. max_hw_sectors is 64Kb in this proprietary driver. I began to test it with a simple sequental read by 100 threads with adjusted readahead size (2048Kb; total ram is 1Gb, I use posix_fadvise DONTNEED a

Raid-1 on top of multipath

2007-04-20 Thread Rob Bray
I'm attempting to do host-based mirroring with one LUN on each of two EMC CX storage units, each with two service processors. Connection is via Emulex LP9802, using lpfc driver, and sg. The two LUNs (with two possible paths each) present fine as /dev/sd[a-d]. I have tried using both md-multipath a