What's wrong with my SAS?

[ed79]

I've just got a Seagate Cheetah 15.4 73GB 15k SAS drive off ebay to go with my new Foxconn Bloodrage MB. All seems to work fine until I ran some benchmarks.

The HD Tune one was as expected - slightly slower transfer rate but lovely fast access times.
(in all pics the SAS drive is on the left, WD 640GB SATA one on the right)

However, surely this below can't be right? The write speed is seriously slow...

But in this test it seems OK again (but no faster than a normal SATA drive)

I had planned to get a 2nd SAS and RAID0 them but having seen the performance of SSDs should I just sell the SAS on ebay and cut my losses?

Intel SSD...

 

[rpstewart]

It looks like you could be coming up against a firmware limitation on the SAS drive. Well maybe limitation is the wrong word....

The SAS drive is an enterprise unit designed to respond to high numbers of simultaneous requests whereas the WD is a consumer unit designed to be as fast as possible in a single user environment. You can tweak the Queue Depth in ATTO to simulate a higher load during the benchmarking which could show the difference between the two.

 

[ed79]

Thanks RP! I increased the queue to 8 last night and it made a significant difference - it's now faster than the WD 640GB but a fair way off an SSD. Important thing is that it feels fast enough in use - bit noisy though!

 

[domyboy]

I have the same motherboard with two IBM SAS drives in RAID 0. They give very good performance, not as good as my two SSD in raid 0 though

 

[Stonedofmoo]

Thanks RP! I increased the queue to 8 last night and it made a significant difference - it's now faster than the WD 640GB but a fair way off an SSD. Important thing is that it feels fast enough in use - bit noisy though!

Very power hungry too. I wouldn't have got one personally.

SSD's are faster, don't need a SAS controller, use a small fraction of the power, are silent, and are actually cheaper than any decent SAS/SAS Controller setup.