I have 3, 3TB WD Red drives on a LSI 9260CV in raid 5.
Read = always read ahead
IO Policy = Cached IO
Write = Always write back
OS= Win 2012R2 latest, firmware Drivers lastest
I did some benchmarks and I can only explain the sequential results. The rest I dont get it, Raid5 is supposed to have slower writes due to parity calculation.
The LSI card has 512K cache and for sure it influenses the results: the numbers get smaller as the ratio cahe/file size changes. While this is normal, there is always 50% more throughtput for random writes and this is consistent whatever the file size. I would expect that ratio to drop also as the test file grows bigger (if the cache was the reason for this strange performance).
Here are results for a tiny file that fits entirely into the boards cache, so numbers reflect PCI transfer not disk perfomance.
What did I miss ?
m a r c