View Full Version : PCI bus error (-6024)

01-21-2002, 07:46 PM
I am working with a B&W G3 450 MHz Mac, for digital audio recording, using ProTools LE and a Digi001.

I've just added an 80 gig ATA hard drive, and Sonnet Tempo ATA100 card, and since doing so, I get "PCI bus too busy" error (-6024) when playing back or recording audio to the ATA drive. I do not get the -6024 error when using my SCSI drive.

Prior to installing the Sonnet Tempo ATA card and IDE drive, I never saw the PCI bus meter exceed 40 to 50%. Now, things will run for 10 minutes or so, then the PCI bus meter gets "pegged" and I get the error message, whenever I play/record files off the ATA drive.

The new 80 gig drive is in 4 partitions, approx. 19+ gigs each. Is there a recommended partition size for ATA drives when using them with PTLE?

Here's my set up:

B&W Mac 450 MHz G3 (Yosemite)
ATI Rage128 display card
Mac OS8.6 (yeah, its old, but its been working fine)
Adaptec 2940U2B -Ultrawide SCSI card - This could be the culprit, but it hasn't given me a problem with my current SCSI drives.

Digi's compatiblity page lists the Adaptec 2940UW, 2940U2W cards as compatible, so I had hoped my 2940U2B would work. The 2940U2B card controls an internal Quantum SCSI drive for OS and apps, and an external Seagate drive for audio files. Here's a note from Brent regarding the Adaptec 2940U2W:

Member # 7660
posted November 09, 2001 08:04 AM ??? ???? ?? ??
Scsi Card Adaptec 2940 U2W
This is your problem.

-Adaptec PowerDomain-series SCSI cards have a burst rate of 512 bytes. This setting is not user-definable in the PowerDomain Control Panel and is the cause of DAE -6042 errors with Pro Tools when installed in a G4. The ATTO EPCI-DC card can be adjusted to a 32 byte burst mode and therefore, does not cause -6042s. In addition to the ATTO card, we also support the Adapatec 2906 SCSI card with PT LE systems:

As I wanted to add a hard drive for more storage, I considered a SCSI drive but so many posts claimed working results with IDE drives, I thought I'd give it a try. My Mac is an older G3 which I believe has a slow ATA33 bus speed, and I was told I'd need the Sonnet Tempo ATA100 card for the new drive. The price of the 80 gig Seagate ATA drive and Sonnet Tempo card was only $275, versus $370 for a 40 gig Seagate SCSI drive...so I thought I'd give it a try.

I've scoured this forum, and Macfixit.com, and xlr8yourmac.com for info on this, but I'm not sure what I'll have to do. Here's what I've done:

1. I tried changing DAE buffer size, disabled visible faders (automation), disabled visible meters, lowered monitor resolution, tried different playback buffers, and other performance tweaks in PTLE. I also reviewed Digi's setup guides for memory, cache, fonts, etc.

2. I've looked for new drivers and firmware updates on the Adaptec site, but none of them list my particular card. I tried a few variants of the card, but none of them would update the firmware.

3. I have an old ATTO Express PCI card, but couldn't find new drivers for it on ATTO's web site. I contacted ATTO and they told me they don't support the card. I tried the original driver but it wouldn't allow my Mac to boot (could be a limitation of the old ATTO card).

4. I set the SCSI transfer rate on my Adaptec card to Fast:SCSI-10 to disable the Ultra SCSI mode, to reduce bus traffic, but it didn't change the PCI meter at all (still pegged).

5. Someone mentioned that if I set my Optical to S/PDIF, not ADAT, it would releive the PCI bus traffic. I tried it and there was no difference. Also, I have a Presonus Digimax that uses the ADAT connection, so this would eliminate the ability to use the Digimax.

6. Someone mentioned turning off Quicktime in the OMS setup. I looked for this, and think I disabled it, but not sure exactly where this option is in the OMS setup. My OMS icon now has an X through it, so I assume its "off".

ANY help or advice on this would be greatly appreciated. If I have buy another controller card for my hard drives, that's fine. If I'm better off just staying with SCSI drives, that's fine too, as I'm not saving much $ if I have to buy another SCSI card due to conflicts with the ATA card/drive.

thanks for your time,
Dave Patterson

01-21-2002, 08:37 PM
OK - I did not have time to read your dissertation. Often the Gurus like a simpler (smaller) post because it is a quick read. Of course that would leave details out but it would get the ball rolling. So I guess I will get the ball rolling...

I do not have any ProTools experience, but I hear its a great app. Digi seems high on many people's lists to.

The B&W G3s have a limited PCI bus - more limited that they probably should have. I think they peak out at around 110MB/s or so with the top end SCSI cards & drives. Your 'stock' SCSI drive probably does not come close to maxing out the PCI bus since it most likely is not setup in a RAID and if it came with the original equipment that drive is a DINOSAUR - probably maxing out at around 20MB/s. Your new IDE/ATA drives can push around 35MB/s maybe a bit more and you have them connected to an ATA100 card - which theoretically can saturate your PCI bus - in reality you could still hit around 60MB/s with the right setup (RAID - IDE isnt all that bad). Of course a single X15 Cheetah could push about 50MB/s by itself - two would definately saturate your PCI card (Ultra2 is 80MB/s) before it completely saturated your PCI bus. The solution if you had a SCSI setup causing these issues would be to lower the sync rates - say to 40MB/s max sustained throughput. I am not sure how this would be done with an IDE/ATA setup.

Another possibilty would be a 'bus master issues'. I have heard that these issues really do not happen, but experience has tought me otherwise. This can happen in say a 6-slot vintage PMac with an older G4 upgrade and a dual SCSI card setup. SCSI RAIDs can be very demanding on the PCI bus and what essentially happens (not sure why a G4 would trigger this) is the two cards are fighting for control and will eventually lock the system up - usually under high I/O rates. The old NEWER TECH claimed to have fixed this issue, but they went bust just after so it is not easy to tell. Sonnet did aquire some of their tech & engineers thought. It seems that XLR8 has finally kicked the problem, but I havent seen any verification of that yet - say from MAGe or KAYE -so who knows.

This could also happen if you did not put the SCSI cards in the 'bus master slots' of vintage PMacs. Slot #1 & #4 are considered the bus master slots since they each are closets to the controller (or maybe for other reasons - they each do have their own PCI controller - normally). The S900 is the one exception I know of - and Umax & JACKHAMMER Storage actually made an UW E100 SCSI card that works flawlessly in the lower (non-busmaster) slots - even with a high performance RAID connected. I any event these 'bus master' issues seem to be much less of an issue with the NEW WORLD MACs because of their increased throughput. The limiting factor on the B&WG3 (yosemite) is the PCI bridge chip - it is essentially the same as the gossamer PCI bridge chip - at least from my point of view. I'm sure the bandwidth on the Yosemite PCI is better than the Gossamer since the Yose has 64bit/33MhzPCI + 1) 66Mhz/32bit PCI for video (or other things), but it is not double like you would assume.

You may have to ditch one of your drive cards - SCSI or IDE - I do like SCSI over IDE/ATA, but money is money http://macgurus.com/infopop/emoticons/icon_smile.gif

To boldly go where no english professor has gone before! -)

01-21-2002, 08:39 PM
double POST! http://www.macgurus.com/ubb/eek.gif http://macgurus.com/infopop/emoticons/icon_wink.gif


01-21-2002, 09:31 PM

Thanks for the reply (almost as long as my "dissertation"). It confirmed some suspicions I had about the PCI bus in that machine.

Can you tell me which will have more strain on the PCI bus:

Two SCSI drives on one controller card
One SCSI drive on one controller card and one IDE drive on another controller card?

Obviously, the PCI bus is overtaxed, so I need to decide how to get more storage without overtaxing the PCI bus. I belive ProTools can access the data I need without fast/wide SCSI, so the bus speed doesn't have to be super fast.

thanks again for your time,
Dave Patterson

01-21-2002, 11:48 PM
Hi David,
Another B&W post. Gotta love em, even though they got's bugs in their heads. http://macgurus.com/infopop/emoticons/icon_smile.gif

Check out the RAID thread that's going: http://www.macgurus.com/ubb/Forum1/HTML/000234.html

As you'll see there are a bunch of PCI through-put issues in the B&W since birth. Apple even came out with a supposed fix in the Firmware ver 1.1 Upgrade. I have installed that upgrade, if you have not, do so. It does make a difference. But it takes pitiful to poor, a minor improvement. Goto Apples G3 support page and do a smart search for 'Blue and White G3 Upgrades' http://www.info.apple.com/usen/g3/

I don't think you should look at your problem as 'overtaxed' PCI bus. That isn't the issue with B&W PCI buses. It's purely the limited write max speed issue that troubles you. The read ability of the B&W does not have that problem.

I am currently running a ATTO scsi RAID0 and an Acard ATA133 Hardware RAID0 on my B&W. There is NO problem with overtaxed or overloaded PCI bus. I have a limit of aroung 50-52 MB/sec on the sustained as well as peak write speed.

That limit is in place even when Gregory had 2 2940U2B cards hooked up with an X15 Cheetah on each card and striped across the two 2940U2Bs. Each Cheetah by itself should be good for at least 50MB/sec writes. He was only getting mid 50's MB/sec at best in the raid.

If your trying to keep a bus totally free to write video on I see no problem with building a second bus in scsi or ATA.....even raid. Just like in Photoshop where you want your scratch disks on discreet buses to max out read/writes you will accomplish the same, but always under the 50MB/sec limit.

Check out the link to Mike Breedans XLR8YourMac page that Kaye posted on the thread I mentioned above and you'll start to see what everyones been dealing with since the B&W came out.

I am not yet ready to give up on the write maximum. I am going to try a couple more things with it.


01-22-2002, 05:26 AM
Thanks for the post, and the info about the G3 firmware update. I downloaded it, will try it and post my results.

From the ProTools (my audio application) posts I've read in the past 4 days, ProTools may process files differently than video or a large Photoshop file. The audio is not loade into RAM, or a scratch disc, like with Photoshop. I used my G3 for Photoshop heavily a few years ago, and didn't have many problems with it then. I never saw any PCI bus error messages.

Thanks again for the info, everyone. Very helpful.
Dave Patterson

01-23-2002, 12:51 PM
Hey y'all; thanks for all your help. Here's the latest on my hard drive saga:

I pulled out the Sonnet Tempo ATA100 card, and installed the Seagate IDE drive directly to the G3's motherboard ATA33 bus, and reformatted the IDE drive. When I did some benchmark testing with ATTO's Express Tools v2.7, I was surprised to find out that the ATA drive was FASTER than both SCSI drives.

Ricks clarified some speed issues in his last post, which made me question the assumption that the ATA33 bus IDE drive would be slower than my SCSI drive...

SCSI drive (f/w Seagate on 2940U2B card):
peak read = 25.47 mb
sustained read = 10.72 mb
peak write = 13.3 mb
sustained write = 11.5 mb

IDE drive (Seagate IDE on ATA33 bus):
peak read = 29.24 mb
sustained read = 19.4 mb
peak write = 28.56 mb
sustained write = 27.18 mb

I initially tried the ATA33 bus to see if I could get the drive to run without the Sonnet Tempo card. It does work, and it seems to have resolved the "PCI bus too busy" -6024 error. The only downside is that the ATA33 bus/IDE drive combo has a 3 to 5 second delay before it goes into record mode, while my SCSI drives don't.

This has been educational for me, and I really appreciate all the help you folks have given me. I'll do more audio recording and playback tests, but I think I'm finally on the right track.

best regards,
Dave Patterson

01-23-2002, 07:50 PM
I was surprised to find out that the ATA drive was FASTER than both SCSI drives.

Well 'speed' as you call it is more accurately called throughput - or thruput (for short) and it not the whole story. You should not be suprised - SCSI is NOT always faster than IDE/ATA. The ATA/33 standard (IIRC) should use DMA (direct memory access) and this does give it very good performance overall - but there are still some big limitations on IDE/ATA.
a) only two drives per channel
b) only one drive per channel can 'work' at any given time - of course this happens very fast so you probably wouldnt notice any slow down - however stripping a drive (RAID-0) across two drives on the same channel often results in NO throughput increase.
c) no external drives
d) cable limitations (see limit C)
e) only 3 year warranties (SCSI should have 5 IF it is sold by a quality vendor)
f) limited RAID abilities - to my knowledge RAID-0 only gains marginally in speed - but you can get some HUGE volumes for cheap http://macgurus.com/infopop/emoticons/icon_smile.gif
g) limited RAID abilities - again - I have not seen a RAID-1 solution (mirrored) that works. Also IDE/ATA RAID cards are expensive - almost as expensive as SCSI cards.
h) rotations speeds are less - top end SCSI run at 15,000RPM. Top end IDE/ATA run at 7,200RPM. This can cause latency (lag).
i) drive capacity is less The Seagate Barracuda 180GB has been out for at least a year (that I know of) and IDE/ATA is just getting to the 140GB mark (there are also issues with many IDE/ATA controllers being unable to handle anything more than 128GB on a single drive.
j) limited expansions - you can run 7 drives off an ancient narrow SCSI bus, an LVD Ultra2 (also OLD) single channel can run upto 15 drives and those dual channel cards - well you get the picture.

YOU PAY FOR SCSI - but then you GET WHAT YOU PAY FOR http://macgurus.com/infopop/emoticons/icon_smile.gif

Have fun storming the castle!