7/13/11
7:24 am

MacMost Now 578: Don’t Stress About Disk Use

Sometimes computer users stress too much about disk usage. They worry when they see varying amount of free and used space and their computers and when they notice those numbers change even though they haven't done anything. Find out what Mac OS X does that uses disk space on a regular basis.

Video Transcript (Click to Expand)
Hi, this is Gary with MacMost Now. I'm here in beautiful Kailua Beach in Oahu in Hawaii, and it's very relaxing here. It makes me want to talk about more subjects that I feel stress people out too much.
A lot of people email me and are concerned about disk space: how it changes, how it suddenly more seems to be used, and they haven't created any new files or downloaded any new software. Well, the thing is, with a modern computer, you can't really worry too much about the exact amount of disk space you have available, because different programs are going to use disk space without you even knowing it, even the operating system itself. So yeah, if suddenly many gigabytes of space go missing on your drive or are used, then you might want to look into it, but for just simply kilobytes or megabytes, don't worry about it to much.
One of the things that disk space is used for is cache files. A cache file is say, when you got a website, like this one, and you look at that logo up there, it takes that logo graphic and stores it in case it needs it again, which, hopefully you will because you'll visit other pages at MacMost.com! So cache can be used for things that are downloaded frequently. They also can be used for other things, for instance, when you're rendering a video file in a video-editing program, it may save some of the data like data used for creating a title or rendering two clips together. It may save that in a cache so that it can use it again later on.
Also, a lot of programs, including the system keep logs of things that are going on. And it'll clean things up periodically, maybe save things for a month or so, but it'll take up space so it will look like you're eating up more disk space as you use your Mac.
So say you notice a few megabytes more are being used on your hard drive, but you really haven't felt like you've done anything. Well, those could be cache files, they could be log files, they could be all sorts of things used by different applications. Even word processors will create cache files, say for how fonts look or different parts of the file. Just actually editing a file, even if you don't make many alterations, will save alternate versions of that file back in time, depending upon what software you're using.
So here are some other things that also may take up disk space, without you even realizing it:
[Text Over Video]
Image Editing (temporary files and scratch space used by Photoshop, etc.)
Virtual Memory (disk space used as a memory cache)
Spotlight (disk indexing taking place in the background)
Background Processes (file sharing and network data being updated)
Finder Data (window and file position and properties)
[Gary:] So, I hope you found this useful. Til next time, this is Gary with MacMost Now.

Comments: 2 Responses to “MacMost Now 578: Don’t Stress About Disk Use”

    Michael Wun
    7/18/11 @ 6:06 am

    Related issue in relation to disk usage, based on experience with ITunes and Time Machine.
    I believe dIsk space becomes an issue, if you want to back up from Time Machine.
    I think you need enough spare disk space to allow for two copies of the files you intend to back up. I think this has something to do with “non destructive” writing to a disk.
    Ie fully write on a new version of the files onto the disk, before deleting the old corrupted files from the disk.
    Hence you should strive for no more than 50% disk usage.
    Right or wrong comment?
    Means that you should always strive to have no more than 50% usage

      7/18/11 @ 7:56 am

      I don’t believe that is true. Even if it were, you wouldn’t need 50% of your disk free, unless every single file on your drive was modified since the last backup. For instance, if you have 200GB being backed up, but only 1GB had changed since the previous backup, one hour ago, then you would just need 1GB of free space to back that up, and afterwards TM would clear out old files to make more room.

Comments Closed.