Effective uses for a RAMdisk in OS X?

Discussion in 'macOS' started by xizar, Nov 28, 2011.

  1. xizar macrumors regular

    Dec 17, 2009
    Tooling around on NewEgg, I discovered that I could dump 16gigs of RAM in my "aging" iMac for about 40USD, so I figured I'd go for it.

    I'm aware that "zomg 4gig only lolz" and "wtf 64bit n00b" seem to be prevailing sentiments when asking if one should use 64bit software or upgrading RAM past a certain point, so I hope to avoid that.

    My question is, basically, are there good uses for a RAMdisk under OS X? Back in days of yore (before hard drives), I used to use them in DOS to load up games and the OS and stuff, but I *hope* that, with so much memory, the OS should never need to be touched.

    I've been doing reading and learned that some people like to put their Minecraft data on a RAMdisk, and seen some benefit from that.

    Are there other scenarios (out side of manipulation of very large multimedia files) where I can make good use of the doubled RAM, either in general or in the form of a RAMdisk?

    What about under Bootcamp? At the moment, I have Win7's swapfile disabled, and never had an issue with it. Can I pimp some of that RAM into a swapfile?

    Thanks for your time and constructive input.
  2. AlanShutko macrumors 6502a

    Jun 2, 2008
    Well, on OS X I haven't found any reason to use any of the RAM as a ram disk. OS X is quite good at using extra ram as a disk cache, so I just let it manage things. (I have a 27" iMac with 16GB.)

    I love that I can have as much running at once and still never hit swap. It makes it a lot easier to leave programs running because you'll need them tomorrow or something. Although, even without leaving them running, the fact that they're in cache will still cause them to load faster.

    The main reason you'd want to move stuff to disk cache is if you have a particular program that's accessing things in a way that doesn't cache well and it's committing the files to "disk" often. Minecraft seems to be one of those programs. Photoshop is not... It does better if you just let it use RAM as RAM.

    Windows under bootcamp is another matter. It SHOULD be caching things as well, but with the legacy of programs stuck under 32-bit land, it seems things aren't as good. I am using a 7GB RAM disk for Skyrim under Windows. I just copy the whole thing into the RAM disk on boot, and let the program run from there.
  3. xizar thread starter macrumors regular

    Dec 17, 2009
    While I don't play Skyrim, I do play Fallout New Vegas (still), so knowing that it helps with that is good to know. Unfortunately, my setup is rather modded (graphics and shaders and stuff), so my FO:NV folder is 13gigs.

    I rather doubt it would be prudent to go with a 13gig RAMDisk and 3 gigs of RAM. :)

    Borderlands, however, is only ... Borderlands is also 13gigs.


    Oh well, thanks very much for your input.

    Also, I'm not sure if you're aware, but there's a (well vetted and trusted) program out that will allow Skyrim to take advantage of more memory than just the 2 (or 4?) gigs the default executable allows. I use the Fallout version and it makes a difference.

    You can search SkyrimNexus for it (or use the link below if you trust me not to rickroll you. :)

  4. brdeveloper macrumors 68020


    Apr 21, 2010
    If you have large Java projects under Eclipse, building/deploying your app is pretty fast with a ramdisked workspace.

    Basically, if you have an application which makes use of HUGE i/o, a ramdisk is a good option. OSX's virtual memory should be enough, but in practice, it isn't.

    Sorry for reviving this topic, but I'm doing some research on this subject...
  5. switon macrumors 6502a

    Sep 10, 2012
    RE: really...


    I would have thought that with today's OSes and fast memory, RAMdisks were a thing of the past. Maybe a RAMdisk might still be useful to load a boot kernel image to run while updating the full kernel, but I wouldn't have thought that too many apps would actually benefit from this. Very interesting.

  6. djdawson macrumors member


    Apr 28, 2005
    I realize this is a bit of an old thread, but one use I've had for a RAMdisk is to use it as a destination drive for capturing high speed network data with tools such as "tcpdump" and Wireshark. For doing protocol analysis at high speeds this can allow these utilities to keep up.
  7. freejazz-man macrumors regular

    May 12, 2010
    thanks for that tip dawson, it's definitely something I'm going to keep in mind for the future
  8. aratio macrumors member

    Feb 26, 2009
    Temporary compile files

    I think a good use for RAM disk is also to use it as temporary storage for header files (since they can be accessed several times in the compile process) and temporarily generated object files.
  9. Isamilis macrumors 6502

    Apr 3, 2012
    Just to share what I've tried recently. I have 8GB / 128GB SSD MBA 2012 with ML 10.8.3. I made RAM Disk for:
    - 1 GB for user's cache folder
    - extra 3 GB for storing and running VM image of my Win XP Parallels Desktop with 512mb allocated for RAM

    What I found is:
    • overall system temp is cooler. I am still looking, what is the real factor, but this is noticeable especially when running XP in Parallels. The temp is also *slightly* cooler for casual tasks (watching moving, browsing, online radio, etc)
    • install XP SP3 took only around 10 minutes up to completion of Parallel Tools installation in XP
    • there is no significant speed difference, running VM under RAM Disk versus SSD, only it feels cooler (the temp is kept normal, around 49-55 celcius)
    • Running aperture and safari seems slightly faster. I'm not sure, how much faster
    • Battery consumption is also reduced. I can watch movie using mplayerx - 2 hours with only small fraction lowered of battery level.
    • All safari cache are cleared automatically when restarting the OSX. This is including Top Sites as well. You don't have to clean cache folder manually (like using Onyx or Yasu)

    I knew, this may not be as scientific as expected. But for now, I think the benefit is worthy.

  10. Mr. Retrofire macrumors 601

    Mr. Retrofire

    Mar 2, 2010
    I use RAM disks for compression benchmarks (compression software development). I use (compress) a copy of the latest Linux kernel source code (just an example). This folder contains hundreds of subfolders, and thousands of files. The compression program must open/read/close each file. This is very time consuming if the folder is on a HDD or SSD.
  11. simie macrumors 6502a


    Aug 26, 2004
    I personally use a ramdisk for photoshop and put its scratch disk in the ramdisk thus speeding up operations. I have been running this config for years and find it very reliable.

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