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  #1  
Old 11-22-2011, 05:50 AM
alex s alex s is offline
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Default Pro Tools 10 - Disk access bug ?

This is something I posted over at gearslutz.com.. But thought it best that I post it here too:

I've moved from PT 9 to 10 for my mobile setup.

I've found something "interesting" while doing some stress tests.

I'm using a 2.4ghz 2008 MBP running osx. 10.7.2 with CPTK.
Recording to 7200rpm external FireWire 400 drives.

In pro tools 10 I'd record 24 tracks (24bit/48k) for about 10 minutes to check CPU and disk access load. CPU was negligible and disk was 13%. I wasn't using disk cache.

When I would stop the recording and go straight back into record, I'd get a 100% disk access spike and a "(-9073) DAE cannot get audio from drives fast enough " error.

I tried again keeping an eye on disk access in activity monitor. During recording I'd see a stable data write (red) on the graph. When recording was stopped, I'd see a stable data read (green).

However, if I went into record while the data read was still taking place, It would throw up a disk access spike, a DAE error and stop recording.

I reinstalled pro tools 9 to check performance and my findings were as follows:

Disk access load during recording was higher (30%).
When recording was stopped, the data read was shown in activity monitor , as expected.

However, if recording was started during the data read, the data read was interrupted and recording would commence normally.

I've switched between PT 9 and 10 a few times to check whether this is an anomaly, but I can recreate this problem every time.

I tried recording 10 minutes of 48 tracks and it took 3 and a half minutes for the data read to complete before I was able to start recording again. Which is obviously unacceptable.

I hope this is just a bug or something strange with my setup... but the difference in disk access load for 24 tracks between pro tools 9 and 10 suggests to me 10 works in a fundamentally different way to 9.

Is anybody else experiencing this problem ?

Al
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  #2  
Old 11-22-2011, 09:45 PM
alex s alex s is offline
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Default Re: Pro Tools 10 - Disk access bug ?

Hello,

Can someone please prove / disprove my findings by doing the following in PT10:

Record 24 tracks for 15 minutes.

Stop Recording.

Start Recording immediately.

Do you get a DAE error 9073 - DAE can't get audio from drives fast enough.

Thanks,

Al
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  #3  
Old 11-23-2011, 03:53 AM
alex s alex s is offline
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Default Re: Pro Tools 10 - Disk access bug ?

I've now recreated this fault using ESATA drives and a different computer (MBP 2011).

Although the tolerances are higher due to the increased bandwidth, the fault still occurs.

Can Digi Tech Support please look into this.

There have been quite a few views of this thread but nobody has done the 15 minute test yet.

I'm more than happy to be wrong about this, but will somebody please either prove or disprove my findings, this needs to be sorted either way.

Thanks,

Al
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  #4  
Old 11-23-2011, 06:30 AM
alex s alex s is offline
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Default Re: Pro Tools 10 - Disk access bug ?

There have now been 140 views of this thread.

Can somebody PLEASE carry out the test laid out in post 2.

Thank you.

Al
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  #5  
Old 11-23-2011, 07:21 AM
C C is offline
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Default Re: Pro Tools 10 - Disk access bug ?

Why would you not use Disk Cache out of interest?

I'll happily run the test as described later but I'm failing to understand why you'd choose to record to the FW400 drives without using Disk Cache as an intermediate step.

Thanks,

Ceri
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  #6  
Old 11-23-2011, 07:31 AM
alex s alex s is offline
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Default Re: Pro Tools 10 - Disk access bug ?

Helo Ceri,

Thanks for getting back to me.

I disabled disk cache to rule it out as a source of the problem.

This way I could do a direct comparison with Pro Tools 9.

Also, when doing a live recording of significant track count,
the recorded material will be way over the available disk cache anyway.
(2008 MBP max ram = 4gb / 2011 MBP max ram = 8/16gb)

I've also recreated this problem using esata drives which are wide enough bandwidth to not require disk cache.
Also the absolute maximum disk access load I was getting recording 24 tracks on FW400 was 30%... so there's no need for disk cache there either.

Thanks for your time,

Al
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  #7  
Old 11-23-2011, 07:53 AM
C C is offline
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Default Re: Pro Tools 10 - Disk access bug ?

That seems reasonable. I'd encourage you to run the test with the Disk Cache as well. You may be surprised at the results. I have (once) recorded 30 (5 x 5.1 busses) DPE tracks back to a networked SATA drive over a WiFi network using it.

It's pretty powerful stuff and is a dynamic cache, it wouldn't need to fit the entire recording into RAM just the area (Total RAM- 3GB) around the playhead.

As I said, happy to run the test as described but you may be comparing apples to oranges.

Ceri
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  #8  
Old 11-23-2011, 08:08 AM
alex s alex s is offline
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Default Re: Pro Tools 10 - Disk access bug ?

Quote:
Originally Posted by C View Post
That seems reasonable. I'd encourage you to run the test with the Disk Cache as well. You may be surprised at the results. I have (once) recorded 30 (5 x 5.1 busses) DPE tracks back to a networked SATA drive over a WiFi network using it.

It's pretty powerful stuff and is a dynamic cache, it wouldn't need to fit the entire recording into RAM just the area (Total RAM- 3GB) around the playhead.

As I said, happy to run the test as described but you may be comparing apples to oranges.

Ceri
Hi Ceri,

That's interesting. I wasn't aware disk cache was dynamic. I thought once it was filled, that was it.

I've had no problems with throughput with PT 10, recording 48 tracks to 1 x FW400 drive for a couple of hours without a hiccup.

It's just if you stop recording and start again before the data read in the activity monitor has completed, you get a DAE 9073 error.

I'll carry out the tests again with disk cache enabled, but I have a sneaking suspicion this will just increase the threshold before the error crops up.

Also, if this is a new feature in pro tools, it doesn't help those who use regular PT10 and don't have access to disk cache.

Once again,

Thanks for your time,

Al
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  #9  
Old 11-25-2011, 02:40 AM
alex s alex s is offline
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Default Re: Pro Tools 10 - Disk access bug ?

I have now had a chance to carry out a few more tests,
and as it turns out the threshold for this fault is a lot lower than I expected.

Using a 2008 macbook pro / 4Gig Ram / PT10 / OSX 7.2

24 Tracks / 48khz/ 24bit / No Disk cache


Recording for the stated time below, stopping, and commencing recording immediately gave the following results:

Rec Time|............|Time for data read to clear (and recording able to start again)

10 mins.................2m30sec

5min.....................1m19sec

2m30sec ...............0m39sec

1m00sec................0m17sec

0m30sec................disk access spikes of 61/75/51% but continued recording



After these tests, I engaged disk cache to see if it changed the results.
My understanding is that disk cache is not dynamic, once it it filled I would see similar results as those above.

Using my maximum disk cache setting of 1gig - it takes 4min23sec of 24tracks at 48k/24bit to fill.

My guess was after 4min23sec plus the times above I would see similar results.

I recorded 6min24 sec (2minutes over the disk cache limit), stopped and started recording again and I got DAE error 9073 and it stopped recording.

Once again I was able to recommence recording once the data read had finished in activity monitor.


I am no expert on coding... but from these results it looks like pro tools 10 is not sending some kind of data read interrupt to the record drive when recording is started, hence it still tries to read off the disk and write to it at the same time.

With the exception of Ceri, I'm very surprised that nobody has looked into this to either back me up or prove me wrong.

If this problem is not just localised to my 2 setups (I've recreated the fault on two different computers, different hard drives and OS's), somebody's going to be in for a shock when they've got a thousands of pounds a minute orchestra on the other side of the glass and PT 10 won't go into record !!!

For the time being I'm going back to Pro Tools 9,

and I'll wait patiently to be proved either right or wrong.


Al
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  #10  
Old 11-25-2011, 05:05 AM
tamasdragon tamasdragon is offline
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Default Re: Pro Tools 10 - Disk access bug ?

There's something wrong there (guess you know it already). I've tried this on a test session, and everything worked without a hiccup. No matter if I left disk cache on, or switched it off.
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