Disk Playback Cache Size?
 

I only migrated to v12.4 last week and just discovered a setting with the Playback Engine that I believe wasn't available in v11: Disk Playback Cache Size.

The manual describes what it does, but I'm unsure what's appropriate for my system:

CPU
Intel Core i7 960 @ 3.20GHz
Bloomfield 45nm Technology
RAM
24.0GB Triple-Channel DDR3 @ 666MHz (9-9-9-24)
Boot drive
476 GB Samsung SSD 840 PRO (SSD)
Dedicated audio drive
238 GB Samsung SSD 850 PRO 256G (SSD)

Default for this is "normal," but there's no indication of what that is.

I understand that the highest value is 4 GB less than whatever your total RAM is, so in my case it's 20 GB, since I have 24 GB of RAM.

How should I set this?

Disk Playback Cache Size?
 

Edit: oops missed you looked in the doc—The Pro Tools Reference Guide gives you an overview, and is useful to reading there about what the disk cache performance meters do. And all this has been discussed lots on DUC in the past (did you try to search for past posts?). Start with it set to a few GB (not “normal”) and observe the performance. We have no idea how much memory your sessions/plugins use (which tells you when a larger cache might cause problems) or how large the sessions are on disk. The size on disk gives a clue how large a cache might be and still help (not 1:1 but it scales).




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Re: Disk Playback Cache Size?
 

Disk Cache has been around a lot longer than 12.

Disk cache uses a section of RAM as a hard drive buffer for audio files. "Normal" is merely a default/dynamic size. Turn disk cache on to a level that isn't normal, open up system usage viewer and load a session, watch the disk cache line and you'll see it "load up" (ignore the RAM line as now some of that belongs to the disk cache.) When the disk cache goes fully green, it is finished loading. If it is at 100%, increase the size of the disk cache as long as the RAM usage isn't also maxed out. If the RAM usage is nearly maxxed out, then that means you need RAM for your other VI and you have no more to spare for a disk cache.

If from the start, after your Pro Tools session is loaded, the RAM line is nearly maxed out, reduce your disk cache.

The disk cache size really depends on how many audio files are in your Pro Tools session but you can't/shouldn't exceed using too much RAM for the disk cache if you need it for other stuff (VIs)

Re: Disk Playback Cache Size?
 

Yes, but HD only, it was added to Pro Tools standard in 12.2.

Re: Disk Playback Cache Size?
 

Thanks, Darryl Ramm and BScout for weighing in and providing very useful info.

Before I posted I moved it from "normal" to 2 GB; cache was barely green and RAM was @ I believe ~30%.

I'll need to experiment with this to find the sweet spot. And I guess it'll vary from session to session.

Thanks again.

Re: Disk Playback Cache Size?
 

BTW I let Avid folks know the latest Reference Guide has mistakes in it where it talks about Disk Cache being a Pro Tools Ultimate feature, e.g. in the the Disk Cache Meter description.

Re: Disk Playback Cache Size?
 

Thanks, Daryl.

I think your comments and those of Chief Technician on another thread

(http://duc.avid.com/showthread.php?p...52#post2397452)

are really useful. The reference guide says what it it, but provide doesn't any guidelines or examples from what I saw.

(I searched the forum after I posted and found this. Sorry--I should have searched first.)

This I found especially useful:

My Audio Files folder for this project is currently 1.23 GB and will likely get larger; I'm thinking I should try and match the cache size to the size of the Audio Files folder.

Does this make sense?

Re: Disk Playback Cache Size?
 

It does if you are actually using all the audio files in the audio folder. The ones that go into the cache aren't just the clip bin. They are the ones actually in a track.

If you are barely green now on your Disk Cache line, then you have very little audio in use at the moment and your disk cache is plenty big.

Re: Disk Playback Cache Size?
 

Thanks for clarifying this. I'm using very few of the clips, actually. (I assume these are the ones that are shown bold in the clip list.)

When the Cache Size is set to "normal: Disk Cache isn't displayed in the System Usage window and Memory is at 25%.

When I change the Cache Size to 1 GB, Disk Cache is 11% and Memory is at 29%.

I don't know which is preferable.

Re: Disk Playback Cache Size?
 

Bold means complete files and not clips. It isn't an indication if it is used or not.

Up to you. I know what my memory vs audio disk cache needs are (even with a 100% SSD system.) I like to be aware of how much disk cache I'm using too. When I work at facilities with shared storage, disk cache is what takes the burden out of NAS or Fiber shares. That way all assets are centralised (and updated) for everyone working on the project but your system runs really well since it is filing the cache to buffer the load on the storage network.

One thing to keep in mind though, with disk cache, if you use something like iZotope RX externally (not audiosuite), you can fix a file with Pro Tools open but the cached version of the file in the disk cache will not have updated unless you close/reopen the session. Something I've learned from experience. If you use the audiosuite iZotope Connect to send/render back from RX, you don't face these issues as you've created a new file that gets loaded into the cache. Pretty much you need to work on the file within Pro Tools 100% so it knows what you are doing. Working with external tools outside of ProTools will create problems.