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Raid Performance Tests:
Adaptec 2940UW Firmware 3.0 vs 4.1 in B&W G3

by Jeff Cusick
Published: 3/15/99

A Blue and White G3 Owner sent RAID test results that indicate that the latest Adaptec 4.1 Firmware for the 2940UW may not be the best performer, at least in his configuration. His results are listed below:
" Mike
I wanted to share the following information with your speed freaks. With the help of the new Adaptec 2940UW 4.1 firmware update I was now able to go BACK to the 3.0 firmware for comparison. I had major problems before this new final 4.1 firmware trying to get back to v3.0. It would just kill the card (and G3 wouldn't boot) necessitating putting it into a PC and flashing it with the PC software before I could flash it with the 4.1beta. I was just happy to get it working. Forget about using Wide to Narrow and connecting Scanners, CD-R's etc. I'll have to wait for a separate card for that.

I have a B&W G3 350 DVD (clocked up to 400 MHz of course). My RAID is set up with 3, 9GB Atlas II's Striped with SoftRaid 2.1.5. I noticed when I upgraded the firmware that they were a little slower but had no way to go back for comparison. Now I do and here you go...

Adaptec 2940 UW firmware version
Mac Bench 5.0 Disk
(8% faster)
MacBench 5.0 Publishing Disk
(4% faster)
FWB HD Toolkit 2.5.3 BenchTest Results
(3.0 benchmark doesn't work with the SoftRAID setup)
Sustained Read
Sustained Write
Access Time
8.6 ms
8.6 ms
Read Transactions/sec
Write Transactions/sec

The BIG difference occurs if you look at the graphs included. At the smaller KB sizes the 3.0 is greater than 2 times faster!!! It probably has something to do with using the SoftRAID driver or drive caches but with v3.0 firmware it peaks at 77428 KB/sec where the 4.1 firmware peaks at 33176 KB/sec. [The graph with the 77MB/sec peak occurred during Random write performance tests and is not shown in the sustained rate figures.-Mike]

2940 ROM v3.0 Results

2940 ROM v4.1 Results

I sticking with version 3.0 firmware as I can't boot from a RAID array anyway. [Unlike older Macs, B&W G3s can't boot from RAID volumes - a limitation of openfirmware that exists in OS X as well I'm told-Mike]

Newer is not always better, especially if your using a RAID on a new G3.
Jeff Cusick "

On a related note - here's a comment from Rod Paine, a VAR with considerable SCSI/RAID experience that wrote reqarding an apparent failure to flash the 4.1 update correctly, which was overlooked and the cause of lower performance. He also notes a negative to the new 4.0 Control panel:

" We previously wrote:
'We don't know why these narrow drives have lost considerable speed with v4.1 firmware and we haven't checked yet what the effect is on one of our older Fast/Wide multi-drive RAID's, where v4.1 wouldn't be talking to a narrow interface, or if perhaps we have some form of interaction with two v4.1 cards in the same G3, which has worked fine to date, with v3.0 firmware.'

After further tests this morning, it appears that one of the two cards selected for the 4.1 flash update, did not actually update. They were both initially selected for update and the Adaptec utility reported that they were updated. We were running with one v3.0 2940UW (or corrupted update?) and one v4.1 2940UW, which evidently created the problem we reported. When reflashed one at a time to v4.1, the cards did properly update and individual card performance is as it should be, when an external fast narrow drive is attached.

Only one negative, with respect to the v4.0 PowerDomain Control Utility. The ability to change the "Target Options" is gone from the Utilities menu. While not a problem for most, René Kropf will tell you that we've used this feature to keep older fast/wide RAID's, such as the ProMax/Conner CR6-RAID six-drive system alive, where only UltraSCSI drives are available for replacement and can only be used if the Adaptec 2940UW is backed down to 16MHz, from it's 20MHz setting. This is due to the long data paths inside the CR6-RAID [As noted in the FAQ - UltraSCSI does not like long cable runs-Mike]. Again, not a major problem, except for our clients with the earlier CR6-RAID.

I guess we could test a '16MHz' 3.0 after it's flashed to 4.1 to see if the 16MHz setting is still in effect, but we're not going to. Our position will now be to only use the Adaptec 4.1 firmware with 2940UW's being moved to B&W G3's. All our 2940UW's, including those involved in pairs to support dual-channel RAID's (pre-ATTO ExpressPCI Pro and Adaptec 3940UW days) will otherwise remain at 3.0.
-Rod Paine
ASTEC Company, Inc "

I welcome other reader performance comments with the latest Adaptec 2940UW firmware.


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