I have an HP DL380 G5 with a P212 controller and a 256MB cache card/battery.
The P212 is hooked up to an MSA60 enclosure, which for testing, I have populated with 8x 500GB 7.2k SATA disks.
I know after a lot of research, that the MSA60 will only negotiate SATA disks at 1.5G, and that the single SAS cable between the controller and enclosure has 4x 300MB/s lanes.
So the max speed over the link is 1,200MB/s, and if I know how RAID0 works correctly, I should get very fast read/write speeds on a RAID0 of 8 disks.
I did a simple crystal disk mark test, and saw it cap at around 360MB/s read. Is that what I should be expecting on this setup, as I thought it would be higher than that.
Maybe my maths skills aren't up to scratch.
So thanks to everyone's input which confirms my understanding of SAS links, the link between the enclosure and controller is not the bottleneck.
What I have started using now, is 4 x 3TB Seagate 7200RPM drives. What is odd, is that two of them are showing with link speeds of 1.5Gbps, and 2 show as 3Gbps.
A disk test on a single disk shows that reads are around 140MB/s, and writes around 110MB/s. If I scale up in RAID0, each disk I add scales the write speeds as expected, with 4 disks providing around 440MB/s. Reads however, seem to reach a maximum of about 410MB/s, but I would expect around 560MB/s in RAID0.
Could this scaling be down to cache settings perhaps?
I would like to use RAID 5 in this enclosure, but if I can't get expect results with RAID 0, I dread to think what my RAID 5 results will be.