HD free space going from 700MB to 7GB w/ reboot?

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HD free space going from 700MB to 7GB w/ reboot?

I have a MacBook Air with a 128GB SSD. I have it partitioned with Bootcamp, and the size of the OS X partition is ~40GB.* It was giving me a message that I only had ~700MB of space left and I needed to clean up my hard drive to continue downloading files. I checked Activity Monitor, and indeed this was the amount it showed as being free.

After I rebooted for unrelated reasons, the partition suddenly showed as having ~10GB free. After a couple of minutes it showed 7.75GB free, where it seems to have stabilized. I did not do anything else to adjust the amount of free space on the HD.

Does this make any sense? What could have happened?

--

* I need to repartition, but that is a separate conversation.

MacBook Air (13-inch Late 2010), Mac OS X (10.7.5), 2GB RAM, 1.86 Intel GHz Core 2 Duo

Posted on Jan 29, 2013 8:33 PM

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Answer 1

Niel

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Jan 29, 2013 8:36 PM in response to jman79

It's probably due to swapfiles being automatically deleted; this is done upon each restart or when the system has enough free RAM that a swapfile is no longer needed. You can keep track of them manually by choosing Go to Folder from the Finder's Go menu and providing /private/var/vm/ as the path.

(75606)

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Answer 2

jman79 Author

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Jan 29, 2013 10:49 PM in response to Niel

Thanks Niel. That could explain it. I'm all too aware that my system is always running out of physical RAM - I only have 2GB, and the current state of 12MB Free with another 500 Inactive is not uncommon (for example as pasted below):

When I look at the /private/var/vm/ path I see six swapfiles and a sleep image, taking up a total of 4.3GB. What I don't understand is why 4 of the 5 swap files haven't been modified since yesterday, nor has the sleepimage file. Does this imply that some or all of these are not functioning correctly? Screenshot of the /private/var/vm/ path below:

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Answer 3

Niel

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Jan 29, 2013 11:04 PM in response to jman79

No, it doesn't; it just means that the system hasn't needed to modify their contents since then.

(75619)

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Answer 4

BobHarris

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57,035 points

Jan 30, 2013 6:44 AM in response to jman79

You need to free up disk space. You are too close to being full.

To keep the swap files down, you have to stop running so many concurrent applications. Quit apps when you do not need then right away. Or stop using memory hog apps. Image and video editing apps are often very RAM hungry.

You Mac does not have a lot of RAM so when you run memory hungry apps or run too many concurrent apps, the Mac needs to swap application data to the pagefile(s). Since this is a Macbook Air with a solid state drive, this is fairly quick, but it does require space on the disk. You either need to leave room for these pagefiles, or reduce your need.

You could use an app such as OmniDiskSweeper to find out were all your space is being used. Focus on stuff in your home folder, and maybe the Applications folder. Stay away from Mac OS X folders as if you delete something critical in those, you could disable your Mac. If you have questions about deleting something outside your home folder, you can ask them in the forum.

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Answer 5

jman79 Author

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Feb 1, 2013 12:41 PM in response to BobHarris

Bob,

You are absolutely right about needing more disk space. Upon further examination I can see that CPU spikes (and slow performance) are almost perfectly correlated with with Disk Activity spikes. As long as I keep the Disk Usage from getting too high this doesn't seem to be too bad. As you said, the SSDs are pretty quick.

RAM consumption doesn't seem to have as much of an effect, which is good since I'm not sure I can do much to consume less RAM w/o making massive adjustments to my workflow. The screenshot of the activity monitor is sorted by real memory consumption, and as you can see it's all going into the browser. I primarily work in the cloud, and I like to keep a lot of tabs open concurrently (10+), but gmail is usually the killer, ranging from 200-600MB. Desptop producivity applications like Evernote, Preview, MS Office don't take up much RAM, and I rarely do any heavy media editing.

For now I am just restarting more often to clear the swap files, but I am repartitioning my drive to have more space on the Mac side. How much free space would you say is necessary for optimal operations?

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Answer 6

jman79 Author

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Feb 15, 2013 3:18 PM in response to BobHarris

BobHarris wrote:

You need to free up disk space. You are too close to being full.

... You either need to leave room for these pagefiles, or reduce your need.

I repartitioned to create an extra 35GB of space on my Mac partition, but it hasn't done anything. I started a new forum discussion here to try to figure out more broadly how I can speed things up. I would love your input!

Niel if you're still reading I'd love your thoughts on the new thread as well. Both of you guys seem more knowledgeable than I in Macs!

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