Bizzare SAS speeds

JamesTuc

JamesTuc

JamesTuc

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Joined
10 Jun 2010
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342
Location
Coventry
I recently bought a single SAS drive and got it connected up to my P6T Deluxe. I got the drive at a very good price so for me it was meant to be a cheap upgrade for my boot drive which was a 1TB F3.

I got Windows on the SAS drive but straight away noticed that if anything it was a lot SLOWER than my SATA drive. I downloaded and ran a drive speed tester "Bart's Stuff Test v5.1.4" and got the following results:

SAS Write Avg 46MB/s
SAS Read Avg 49MB/s

SATA Write Avg 124MB/s
SATA Read Avg 131MB/s

Is there a setting I can change to get better speeds on my SAS drive? I really don't understand why the SAS drive is so much slower, please help.
 
just tried bart's stuff test

my SSD read avg is about 50mb which is slower than my old 250GB hard drive lol

sorry that software is not very good. you need to try different benchmarking like atto, hd tach etc
 
Will try something else, but regardless of how bad it is, if there is a very noticeable speed difference between the two drives when booting then surely something is wrong?
 
What sort of drive is it?

A SAS connector doesn't necessarily mean that the drive will be fast. It could be anything from an old 7,200rpm near-line storage drive to a modern 15,000rpm performance drive.

Sustained transfer rates are almost completely irrelevant for an OS drive.

If it's a server drive the write cache could be disabled.

A server drive won’t necessarily make a good desktop drive. For the desktop the second generation 10,000rpm Raptors used to beat then then best of breed 15,000rpm server drives. Those same Raptors are now probably slower than a F3 in everything apart from seek speeds.
 
It's a 10k 72GB HP SAS drive (server I think because it came with the bracket for slotting it in) the model no is dg072a8b54

How do I enable the cache?

I'll try CrystalDiskMark and let you know the results.
 
Ok, I ran with all default settings and did the All test. I ran the test twice on each drive.

Results for F3:

F3-1.png


F3-2.png


Results for SAS:

SAS-1.png


SAS-2.png
 
Seems normal. Your F3 has 500GB platters, your SAS one has maybe 2x36GB ones. That's terrible platter density so you get low sustained transfer writes, but notice how thanks to the rpm the smaller writes are quicker.

Even if you had the latest 15k SAS drive with bigger platters it wouldn't be that impressive on the desktop (relatively speaking) as the firmware is designed for high load.
You can't expect much over an F3 anyway, only real upgrade is an SSD. Velociraptors and SAS drives won't feel significantly faster and older ones slower.
 
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