Need SCSI Help

[Bozo]

I purchase a LSI Logic 'LSIU160' and the SCSI cable from Newegg. I've attached a Seagate Barracuda ST39236LC to the cable/controller combo. After getting everthing setup, I ran ATTO. Seems the best this drive can do is ~25MB/sec. Seagate specs say I should get 40MB/sec or 80/160 in LVD mode. I realize that I won't get 'specs', but it appears on ATTO that something is clamping it at 25MB/sec. I've been through all the settings I can find, added a jumper to get into 'sync' mode, and changed cables ( robbed from a server with Cheetahs in it. ) I was expecting ~33-35 MB/sec.
I then tried a Cheetah on this card. It only gets ~73 MB/sec. I was expecting ~ 125-135 MB/sec.
Granted the card was cheap, but am I paying for it now with poor performance?

Bozo :mrgrn:

 

[The JoJo]

Check out the product manual, min to max is from 24.7-39MB/s.

One moment, I've got the link here somewhere...

 

[The JoJo]

Here:
http://www.seagate.com/support/disc/manuals/scsi/67535b.pdf

 

[The JoJo]

Section 4.2.3, the above figures seemed to have been for one 512-byte track.

 

[The JoJo]

18XL, was that a 9GB model? 7.2k rpm.

Get a Seagate X15*

 

[Bozo]

Interesting; I'm just barely making the minimum.

Further down it give the synconous transfer rate as 40MB/sec.

Most confusing


Bozo :mrgrn:

 

[The JoJo]

Ah, you're talking about the speed of the BUS, not the actual drive here. That's the speed of the Ultra Wide (UW) 40MB/s bus it uses. U2W would be the 80MB/s and so on, but what the drive can push out onto the bus is another matter.

 

[The JoJo]

You said you the tried a cheetach? What Cheetach? 73MB/s is very good in my opinion. For large data amounts, that's pretty much the STR of the drive, not too much interference from cache.

Perhaps you should try some other benchmarks also?

 

[Bozo]

I tyried a Seagate X15 on this setup. Getting~ 73MB/sec. Seems slow. (for an X15)

Bozo :mrgrn:

 

[The JoJo]

Atto gives me weird results on my Atlas 10k3 (14MB/s max).

Try out the latest HDtach :

http://www.simplisoftware.com/Public/index.php?request=HdTach

and post the results you get from that.

 

[The JoJo]

Isn't the upcoming X15.4 able to push about 90+MB/s on it's outer tracks? STR. Burst speeds are then limited by PCI bus etc...
Compared to that it's not bad, if we're talking about STR.

 

[Santilli]

You are doing great.

The X 15 is running fine, and so is the other drive.

UW max is around 35-7 mb sec, real world.
LVD max is around 75 mb/sec, real world.
Haven't tried the 15.4, but my 15.3 maxed at 73 mb/sec.
s

 

[Santilli]

Check that. That 15.3 maybe defective. You can send it to me, and I'll try it in Raid O, with the other one I have, and I'm sure you'll find it's defective.

:wink:

s

 

[Bozo]

I guess my expectations were too high. I tested a WD400JB and it averages 49 MB/sec. Thought the SCSI drives would smoke it. The X15 did, but I was expecting over 100MB/sec.

But, the better access times seem to make up for the slower speeds. This is more of a percieved 'feel' than hard numbers.

All the testing was done in the same computer; just switched drives in and out.

Sure did learn a lot about SCSI too.

Thanks for all your help

Bozo :mrgrn:

 

[Howell]

You should get another X15 and try RAID0. It has even more percieved speed. Woot! :wink: