Just upgraded Early 2011 Macbook Pro w/ 4GB RAM to 16GB RAM. System now sometimes runs smoothly and other times pauses frequently.

Terminal keeps giving me 'System is low on disk space/memory' error. I have 12GB free disk space and 16GB RAM for God's sake. Activity Monitor says I got 10GB RAM free. So why is it saying I'm low on disk space? Lion also says sometimes that I'm low on disk space.

This often happens when spotlight finishes indexing, I guess then system think it's low on disk space (even though I have 9 gb free at that point), then it appears that spotlight trashes its index, systems becomes smooth again, spotlight re-indexes, and same thing happens again.

My theory so far is that if I have 16GB RAM, then the OS is for some reason trying to reserve atleast 16GB Swap Space on disk 'just in case I run out of the 16GB RAM'.

Is this true? Does this make sense?

I really don't want to free up more hard drive space. I already have a 128GB SSD which is small enough as is, and 16GB RAM should be plenty enough for the OS' memory needs.



  • One more thing...when the system pauses, I see a process called 'powerd' taking up 100%. Not sure what this process does. Google doesn't show anything.
    – Hisham
    Mar 23, 2012 at 18:44
  • wow 16GB - maybe the hamster is spinning that wheel so fast he cant control it anymore!? Mar 23, 2012 at 19:01
  • @GraemeHutchison Apple's all about cyborg hamsters these days. They can spin really really fast. especially with 16GB of ram.
    – Adam Davis
    Mar 23, 2012 at 19:03
  • Incase the error is caused by memory: I got a crucial memory kit from amazon that is advertised as Apple compatible and lists all compatible models. Price is good and didn't have any issues. Also I don't know the use of your computer but unless its really really heavy 8gb is more than enough.
    – latusaki
    Mar 23, 2012 at 19:12
  • I purchased a Corsair kit with the part number CMSO16GX3M2A1333C9 which you can buy from many places. It works fine in my MBP 17" early 2011.
    – Adam Davis
    Mar 23, 2012 at 19:20

3 Answers 3


I got the "System is low on disk space/memory" error as well as a number of other intermittent problems when I upgraded my original apple memory. It turned out to be either bad memory, or marginal timing specs.

Startup disk has no more space available for application memory?

When I put the original memory back in, the problems went away - so try that if you've exhausted your other options.

I did eventually do a little more research and found a 16GB set that very closely matched Apple specs for my early 2011 macbook pro 17 memory, and it's had no problems for several months now.

I suggest trying out the original apple memory and seeing if the problem goes away. If it does, return the memory you have, and see if you can get a different set that works better.

  • But do you run into any issues when you have less than 16gb of free disk space? Have you ever gone into that scenario, or do you always have more than 16gb of disk space? I also run into this situation when I have less than 16gb of free disk space available. Memory seems fine otherwise.
    – Hisham
    Mar 23, 2012 at 20:42
  • @Hisham No, I always had ample disk space remaining - much more than 16gb free.
    – Adam Davis
    Mar 23, 2012 at 20:42

I looked into it some more and what my OS is trying to do is create the sleepimage file. This file I believe is being used for hibernation, even though I'm not trying to hibernate at the moment. Maybe Lion is trying to be smart and have that file created beforehand so that just in case I want to hibernate/sleep it can do that quickly.

So it kind of makes sense that 16gb of RAM would require 16gb of disk space, if you want Lion's safe sleep feature. So options are to either disable this feature or live with 16gb of your hardrive being taken up for this feature.

I called Mushkin support (the makers of my memory), they weren't very useful but said 'I was on the right track', lol.

I'll run some memory tests and look into how this safe sleep features works some more. But for now, I think this is the cause of this problem. I think the memory is fine.

If people think otherwise though and that this is not normal behavior of OSX, let me know!

  • Yes, I'm a 100% confident safe sleep is the cause. System puts all memory on disk in case of power loss. See this article: macworld.com/article/1053471/sleepmode.html on how to disable it if you want. I haven't decided yet, but might disable safe sleep to free up those precious 16gb!
    – Hisham
    Mar 23, 2012 at 21:13
  • 1
    Windows works in a similar fashion. The hiberfil.sys file is analogous to the Mac OS sleep image file. It is also the same size in disk space as the amount of RAM. Windows provides a way to permanently disable it within the OS, although it's not widely known.
    – user9290
    Mar 23, 2012 at 22:36

The first step in troubleshooting is to shut the computer down and unplug the external power, remove all the new RAM, and replace the old RAM in the same configuration before the trouble started.

Then see if the trouble goes away. If it does go away, then your RAM is either the wrong specification or it is the right specification but is defective.

I always check specifications with Other World Computing, who specialize in RAM upgrades for Macintoshes.

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