Bad disk performance on HP DL360 with Smart Array P400i RAID controller
Solution 1:
The write performance on that particular controller is usually poor unless you also have the battery unit for the cache. In addition, reconfiguring the array as a RAID 1+0 would give you the same amount of space and better overall performance.
Are you testing this from the ESXi console or from within a VM?
Solution 2:
You don't have the optional BBWC do you? My performance under ESX4 was horrible (5mb/s reads/writes) without one. Its stellar with one (10x improvement). Without the BBWC the array controller disables write-back cache, and performance nosedives as a result.
As a heads up -- my server was also missing the $50 cable that goes from the BBWC to the P400. Make sure yours has one, if not, its cheaper to buy them together.
Solution 3:
My performance varies between 80 and 350MB/s for buffered read, you can go into the smart array tool on smart start and enable the various options, including cache with/without battery if you want for each logical drive, and on disk cache for the array which is normally off, you can do this after creating the array.