Buffer Underrun Errors

[spandol]

Hi Marc,

I haven't been home, I will be back on the 22nd. After that I will let you know if 2.2 helps my problem of buffer underruns. Sorry I can't let you know sooner.

Thanks,
Steve

[spandol]

Hi Marc,

Well I started using MLCD 2.2 but I'm still having problems. So far I've done 2 burns. The 1st went fine, the 2nd gave me a buffer underrun error Code (0B, AD, 00).

I'll try a couple more this week and let you know. This is getting real frustrating and expensive. Any way it could be the CD burner itself?

Steve

[spandol]

Hi Again Marc.

Well I tried my last 2 CD's that I have and I got a 50% return. One worked fine, the next got the same error as in my previous post. On these two I jumped my HD buffer size to 24 from 8 hoping this would solve the problem, but it didn't.

So in closing out of 4 CD's I only got 2 with no buffer underruns. I don't know what to do

Steve

[Digi Engineering]

Hi Steve,

Sorry to hear that you're still having buffer underruns -- I was hoping that it was an OS 8.6/MLCD 2.1 problem and that 2.2 would greatly improve the situation.

(0B, AD, 00) does seem to be a buffer underrun indeed.

I wouldn't imagine that it's your drive, especially since you told me previously that you had sent it to be recalibrated -- I would think that they would've run some diagnostics on it, but I could be wrong.

I would have to guess now that there's a conflicting extension (possibly installed with OS 8.6?) or some other configuration problem with the Mac. Do you have another Mac or a friend with a Mac so that you can try your CD-R out on another computer?

The Toast CD reader extension and FWB CD-ROM toolkit are two extensions that are known to be problematic. Try running with a minimal set of extensions.

Another possibility is it's a SCSI cabling/termination issue. Seems less likely since you seemed to indicate things worked much better before you upgraded to OS 8.6. The standard advice, in short, is watch for SCSI ID conflicts, use good quality, short cables, and termination (preferably active) at the ends of the bus.

While playing with this stuff, you can check the "test mode" box in the "Write Compact Disc" dialog -- that way you don't waste discs while your tweaking.

-- Marc

[spandol]

Hi Marc. I will try that. There are some things that are weird though.

I never had this problem with 8.5.1 so I tried booting from an 8.5.1 drive but the problems continued. I'll look for an extension problem.

I don't think it's the cabling because up until I changed to 8.6 and changed media types I had no problems at all. I checked SCSI ID's and they are fine. I have a very short cable, the CD writer is my only device and it is terminated.

I had no problems using TDK discs but at the same time I upgraded to 8.6, I switched to Maxell. These discs seem really picky. I started a burn on the Maxell and a couple of seconds later I quit the burn. I couldn't use the disc again. I don't remember the TDK's doing that.

I'll try the burns in the test mode. I know it's the same except it doesn't actually write but I only get the underruns when I do a write, not in the test mode. The test mode always works fine.

Oh yeah, My extensions are only 8.6 base extensions and the digi ones. I turned off appletalk but this didn't help.

I'll take your suggestions and see what happens.

Thanks,
Steve

[This message has been edited by spandol (edited 09-27-99).]

[Digi Engineering]

Hi Steve,

That's most curious that you only get the problems when doing real writes (not test mode). Makes me wonder if it could be a media problem...

I've used TDK blue's mostly and some Mitsui gold's with the Yamaha drives and both seem to work well. I seem to remember that our test results showed blue dyes work better than green dyes on the newer Yamahas -- I think Yamaha used to optimize for green and this changed a while ago.

So add to my list of suggestions, reverting back to your old TDK media and see if that improves the situation.

-- Marc

[spandol]

Hi Marc,

Well, Things are a little better but I still get the underrun error every 4 to 5 burns. Also, sometimes after a burn, I click on done and my computer freezes on me.

Here's how I'm running now:
1)Very few extensions running (I don't have FWB CD or Toast extensions) Only digidesign ones and ones that the Mac OS needs.
2)I changed my cache to 512k. It was at around 4098k
3)I'm running from a disc image though, I get the same results running in real time
4)I'm using the same short cable and the CD-R has a unique SCSI number

I talked to Glyph and they said that if I do all of this and it still gives me underruns, it may be a hardware problem. So, Monday I think I will send it back to have them check it.

I didn't think these drives were that unstable.

I just tried to do a real burn (not a test) for something I wanted to have before I sent out the drive and bad luck -> buffer underrun.

I don't know what to do....

Steve

[This message has been edited by spandol (edited 10-01-99).]

[Digi Engineering]

Hi Steve,

Sorry to hear you're still having troubles. Is your computer networked? Have you tried removing it from the network? Also, have you tried defragging the audio drive? Do you have the latest drivers for your hard disk? Are you able to try the CD-R with a different computer?

It's unfortunately very hard (as I'm sure you're realizing) to diagnose this type of problem. The key in CD burning is to maintain the required data rate to the drive fairly consistently (fairly, because the drive buffer will allow for a certain amount of latency here and there). Unfortunately, the Philips 2600 is lacking a bit here -- it only has a 1 meg buffer (fairly typical for a 1X/2X drive though), so it's going to be more sensitive to delays. Most newer drives have 2 meg or 4 meg buffers so they can support higher speeds.

If you're getting a buffer underrun for every 4 to 5 good burns (and the burns are similar in length, speed, etc..), it suggests that the system is capable of supplying the needed throughput, but some occasional event may be happening that it is causing a delay that the buffer can not handle. Things that could do this could be a thermal recalibration (some older hard drives do this periodically), interruption of the burning process by other processes such as e-mail or network access, a fragmented audio drive that causes a lot of seeks, SCSI errors that cause retries, etc...

-- Marc

[spandol]

Hi Marc,

Yeah All the stuff you have suggested I have tried, except trying it on another computer.

What, in your opinion are better drives today? If it still doesnt work after sending it to Glyph, I'm going to find a way to get a new one.

Steve

[Digi Engineering]

Hi Steve,

First off, I can't guarantee that getting a new CD recorder will help your buffer underrun problem, although it might. Perhaps you can make sure to get it through a channel that offers a good return policy.

Digidesign recommends the CD recorders listed at the following URL for use with MLCD 2.2.

www.digidesign.com/compat/MLCDSpecGrid.pdf

Since you're getting buffer underruns, it might be a good idea to choose a recorder with a larger buffer size, such as 2 MB or 4 MB. The 4 MB drives are all 8X drives -- which of course is very convenient but more expensive.

-- Marc