UW SCSI HDD perofming slower than IDE

[Aerobang]

I have an IBM 4GB UW HDD with an Adaptec AHA-2940UW controller. When writing large files to disk I get bursts of writing for about 3 seconds and then a pause of about 3 seconds, over and over again. When it is writing it does it v. fast, but it still gets outperformed by my UDMA-33 second HDD.

SYS: Win98, PIII 450, 256MB RAM

In general it seems to be slower to access than the IDE drive. Have I wasted my money?

The adaptec recognises the drive at bootup, along with my SCSI CD-RW. Strangely, Sandra99 PRO thinks that it is an IDE drive, and reckons my IDE drive is faster.

Surely there is something that can be done about this?

[toms111]

It sounds like you may have a termination problem. Is the IBM drive the only thing hooked up to your SCSI card? The scsi card is automatically terminated but you have to make sure that the drive end is terminated too. Does your drive provide jumpers for termination? If it doesn't you will need to utilize a cable with termination or add a termination device to the end of your cable?

[Aerobang]

The HDD is the only device on the UW port, my CD-RW is hung off the SCSI 2 port. The cable that I am using with the HDD has 3 input connectors, the first one is unused, the second is plugged into the HDD and the third (about 2 inches from 2nd) has the terminator on. Cable & terminator came with the card.

I haven't tried moving the drive or terminator, but if that were the problem then it would seem strange that the drive works at all.

I have considered buying EZ-SCSI from Adaptec to look at its card diagnostics/tweaks. Has anyone used this to good effect?

[Bleeding Edge]

Is the CD-RW terminated?

[Aerobang]

That could be the problem. There is no terminator on the cable because it only has a plug at each end.

I will try disconnecting the SCSI 2 device completely.

[toms111]

Your description confuses me a little: "The cable that I am using with the HDD has 3 input connectors, the first one is unused, the second is plugged into the HDD and the third (about 2 inches from 2nd) has the terminator on. Cable & terminator came with the card." Is the terminator furthest from the scsi card? If so ok. I like the idea of disconnecting the cd drive. Just make sure you disconnect the cable from the card.

[Aerobang]

Yes, the terminator is on the plug farthest from the card. I unplugged the CDRW cable from the SCSI card. This has not improved performance.
I have also tried totally disabling IDE in the BIOS incase it was confilicting for system resources/time. This also had no effect.
What sort of speeds should I be expecting of an UW SCSI disk compared to IDE?
Interestingly, a bench test on Sandra gave 6260 for my UDMA IDE (Fujitsu 6GB) drive and 6549 for the SCSI. Then it gave 10002 for a similar IDE (Maxtor 8GB) drive on my second machine. Could it be that there is some kind of system bottleneck which is preventing transfers above a certain limit?
The drive's lowest performance is in a sequential write test 1.8MB/s, compared with 4 and above for my IDE drives.
Am I wrong to think that an UW SCSI disk with 6ms access time should perform better than IDE disks with 9ms access times? The SCSI bus is huge in comparison.

[Bleeding Edge]

Couple other simple things you can do...

-Check the SCSI adapter's bios settings. By default, wide negotiation should be enabled.

-Update the adapter's bios and drivers.

-Try a different scsi bench test.

-call IBM tech and ask if this is normal performance or if you should replace it.


Note:
-If the scsi drive isn't the boot device, use a higher ID# such as 6.
-Terminate it at the drive if possible, or at least, terminate the cable with "active" termination.

[Axel]

Bleeding edge covered most of it, but have you done the simple thing and checked device manager in safe mode to see if there are any system conflicts which may be triping you up? Go down into the systems at the bottom of the list. A bad PCI bus driver could be your problem before you even get into the SCSI card. You might check for a new bus driver at the mobo web site.

On the other hand, you may have just gotten either a bad hard drive or a bad SCSI card.

[amauri]

Is it possible that you are using a U2W-LVD drive on a UW-SE controller or vise versa?
If you have a 2940-UW then make sure that the SE jumper is pluged on your drive (if there is one).
Which model IBM drive do you have?
My IBM 4.5 UW-SCSI drive is a DDRS-34560D model and can be used in U2W or UW mode by switching the jumper.

[Aerobang]

The drive is an 4.5GB IBM DDRS-34560W. This means that it is Ultra Wide, IBM uses 'N' for Ultra, 'W' for Ultra Wide and 'D' for LVD (U2W).

According to the documentation the force SE mode jumper only applies to the LVD version.

amauri, your drive is being forced to work in the same mode as mine, and so should get pretty much identical performance. What sort of speeds do you get? Do you have results from Sandra, ZD Winbench, or others?

Are there any specialised SCSI benchmarking programs?

The BIOS on the Adaptec AHA-2940UW does not have any options that seem to be relevant. There is nothing about Wide/Ultra Wide negotiation, setup, or anything. The only speed related option is the max synchronous speed allowed which I have set to 40MB/s; the highest in the list.

The only useful data I found on the IBM website was in the pin connections of the drive, for an access LED. Shame it doesn't signify high speed access when it's on!

[cechip]

Actually there is the Wide Negotiation, unless you bought an OEM controller (Firmware provided by that company). In this case, you might want to flash your BIOS to the lastest version.

As for the drive, I believe it is the IBM 9ES drive. Depending on the model of the other 2 IDE drives, it is not uncommon for newer IDE drives to beat SCSI in such test. Such synthetic benchmarks test the performance of drive in a single task mode. For data transfer IDE will always beat SCSI (same drive model), where SCSI shines is during multi-tasking or heavy I/O.

Popular benchmarks are ZD Winbench or Apdatec Threadmark

Simple test: during defrag, load and run a few programs. IF IDE, you will see that the program took a much longer time to respond to your commands and scrolling is much slower. For SCSI, the situation will be much better.

[cechip]

Check out performance of drives at www.storagereview.com (http://www.storagereview.com)

There, the IBM 22GXP is faster than the Cheetah ST39102LW in most ZD Winmark. Same for me. My IBM 13.5GB (22GXP) is faster than my Cheetah ST34502LW in ZD Winmark.