ServeRAID-7st

[jeffmurray]

Hi All

I have the above controller in an IBM workstation hoping to get write speeds at about 200mb/s.

I have it in PCIx Slot 6 and am only getting speeds at 42mb/s with a 2 disc RAID 0 using IBM (western digital) 250mb SATA discs.

I tried a 4 disc array with unmatched mixed (from 160GB to 300GB) SATA 1 and II and it was worse at 35mb/s.

I am presently awaiting two more matched IBM drives to match the other two. However I am not very hopeful that I will acheive my goal. I read on a Macintosh forum that these speeds are acheived with their PCI cards and 4 drive RAID 0.

Any help would be greatly appreciated, please.

Regards

Jeff

 

[jeffmurray]

PS I have the SATA drive supplied with the system operating from the mainboard. Is this OK - I thought I read somewhere that all drives have to run from the PCI controller, however this will mean I can only operate a 3 disc array and that would lower speeds even more.

 

[scsiraid]

200MB/sec sequential write data rate out of a two drive SATA RAID 0 is unrealistic. The media rate on that class of HDD is about 65MB/sec sustained (per WD website). Add a low end RAID controller and the data rate goes down from there. You didnt mention anything about the workload you are throwing at it... what size writes are you doing? What stripe size do you have the array configured to? For large block sequential IO, you want the stripe size to be as large as possible. If your workload will get no benefit from the caching offered by the 7t then you may be better off with SW RAID to minimize the latency induced by the RAID cards puny IOP. Your Intellistation may support HostRAID via the system south bridge depending on what model it is.

As to your PS... you can put drives wherever you want.