Purge That Disk Cache!

You may have noticed that your disk is getting more and more full for no explanation, and even though you regularly move finished projects over to external drives, the space just isn’t freeing up to what it used to be. I had this issue on my Macbook Pro. I’d been working with After Effects CS6 for some time, and then recently upgraded to After Effects CC. I would have imagined that when uninstalling the CS6 version, that all files related to it would also be removed. Well, in short and sweet: no.

There are two key factors to bear in mind here:

  • Adobe After Effects CS5.5 and later keeps a cache of all its rendered frames, so when you’re scrubbing through your compositions, it’s writing those renders to your disk and storing them.
  • Though the size of allocated space is adjustable, by default in CS6 and above, it’s set to 10% of total disk space.

“THE MAXIMUM DISK CACHE SIZE SETTING SPECIFIES THE NUMBER OF GIGABYTES OF HARD DISK SPACE TO USE. IN AFTER EFFECTS CS6, THE DEFAULT DISK CACHE SIZE IS SET TO 10% OF THE VOLUME’S TOTAL SIZE, UP TO 100 GB. IN AFTER EFFECTS CS5.5, THIS AMOUNT IS 20 GB, BY DEFAULT. BECAUSE OF THIS, MANY MORE FRAMES ARE ELIGIBLE FOR DISK CACHING THAN IN PREVIOUS VERSIONS.” – ADOBE

So while its very useful that AE does this, it would be great if Adobe made you aware of it first, especially as it’s not a straight forward task to find where the cache is stored. Now obviously they do offer a purging button in the preferences, which will get rid of the Cache folder of the version that you are currently running. However, say you’ve been working on projects in CS6 and suddenly switch to CC, all of the Cache files from CS6 will remain, even after having uninstalled it. If this is the case for you after having updated, you’ll need to manually go into your system files and find that space waster yourself.

To do this I used OmniDiskSweeper, a free and fantastic bit of software which allows you to navigate your system whilst sorting everything in order of size, so you can immediately see where the largest files and folders are on your machine.

Once I found the Cache folder from CS6, I was able to delete it and free up a ton of space. I then took my curiosity to the mac Pro tower I use at work, as it’s gone through CS4, CS5, CS5.1, CS5.5 and CS6, as well as Final Cut Pro 7 (which is a monster for rendering). Get this: I was able to free up more than 600GB of renders from old projects which have been archived, never to be seen in production again.

Adobe's Cache System
Adobe’s cache system on my desk tower at work.

Now since I went through this ordeal I’ve made it a habit, with my own equipment, to purge the memory from within the software when the project is locked, exported and finished. That way I can move it over to a drive and forget about it. If I ever need to open it up again, then I’ll just purge again when I’m done. A lot of people prefer to work entirely from an external drive, and even set up their cache folder and scratch disks on there, but personally I invested in a powerful laptop because of the portability, so having to have an external drive plugged in when I’m working sort of defeats the point. This is why I paid a ton of money for an internal SSD!

So remember, if you’re wondering why your disk is filling up, and you can’t seem to find the reason, it could be because your disk cache is getting big. If you’re planning on upgrading versions of any software, make sure to purge the disk cache or render files before you do so (provided you’re done with the project of course), as they will stay there even after the old version has been uninstalled, and depending on the software, the new version may just start re-writing a new disk cache of its own while exactly the same data wastes space in the prior version’s cache folder.

Thanks for reading. If you happen to have some better advice for me than what I’ve written above, by all means send it my way, I’m always glad to learn more than the little I know!

Cheers.

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