I've been testing a SAN with fibre channel disks and I get 500MBPS Writes 200MBPS sequential reads and about 5MBPS randon reads / 1000 IOps max. Any idea why reads are so much slower? It is a 3PAR SAN attached using fibre channel switches.
Seems we only had 24 Fiber drives, rated for 200 iops and they were overloading them to 300. We now have 48 drives which seems to have helped writes (2 more controller nodes with more cache) but random reads are still the same. seems it may be related to HBA / OS tuning at this point. Any ideas of what best case random iops would be from 48 FC drives?
Best Answer
Without more details this is tough to answer. 2 things that come to mind are:
2 is the most likely scenario. Remember that the 3par, by default, shares all disks across all luns (much like the HP EVA). This means that one application or server could bring your performance thru the floor.