I have an Intel RS2WC080 RAID controller card connected to an array of 8 WD Black 4TB SATA3 drives, in a RAID5 configuration.
While the read speed is ~750MB/s the write speed hovers around 45MB/s. I know RAID5 is slower for writes, but this is not exactly what I expected with this setup. On an older machine, a Mac with a similar sized RAID 5 array using the same kind of physical drives I get around 430MB/s write and 450MB/s read.
I tried some of the suggestions from the Intel site; http://www.intel.com/support/motherboards/server/sb/CS-029227.htm but a lot of the options - like setting write cache policy to 'Write Ahead' and read ahead policy to 'Adaptive Read Ahead' - aren't possible either in the RAID BIOS settings or the Web Console software.
Another thing that's annoying is that it disconnects every time the computer sleeps, and doesn't reconnect on wake. The symptoms are that the volume doesn't show up at all to the OS - if I open the Windows Disk Management program it's visible at all. I'm coming back to windows after a while away, so I'm not sure where I'd find logs to look at.
Can anyone give me pointers on how to improve this situation?
Additional info: Z9PE-D8 mobo, 2 x (Intel E5-2690 x 10 cores @ 3.0Ghz), 64Gb RAM, Windows 7 64-bit
EDIT: it looks like Intel are playing sillybuggers somehow. Although they list it as a RAID 5 compatible card, it's based on an LSI AS2008 chip which only does 0, 1, 1E and 10. This could have something to do with it.