How much hard drive storage is needed for Time Machine?

Discussion in 'Mac Basics and Help' started by icen1ne, Nov 23, 2009.

  1. icen1ne macrumors newbie


    Nov 23, 2009
    University of Waterloo
    I have a 500 gb ext HD, that i will be partitioning to 2 sections, one will be mac os extended for time machine, the other will be fat32 for storage and so that i can use the hd with windows and mac.

    so my questions are:

    1. how many GB should i leave for back up so that time machine works effectively?

    2. any suggestions on how i should divide the 500 gb between mac os extended and fat32? such as 250/250 or 400/100?
  2. old-wiz macrumors G3

    Mar 26, 2008
    West Suburban Boston Ma
    It depends on how big the drive you are backing up is and how much of the space is used and whether or not you are excluding stuff from backup. I would think you'd want it at least as big as the disk you are backing up from.
  3. Tumbleweed666 macrumors 68000


    Mar 20, 2009
    Near London, UK.
    Its not just how much data you have its also, how big are the files that you are changing?

    For example, if you add 1Gb of (say) hundreds of pictures and music files, then that will only take up the same amount, 1Gb on the TM disk.
    OTOH, if you have just one 500mb video file you are editing, and you edit that once every few hours over a week, **each** backup of that file will take up another 500Gb, so that one single file might take up many times that, maybe 10's Gb. (maximum I think is about 55x filesize. That would be extreme and would be for a file you were continuously altering every day. A VM file would be a very poor candidate for TM :)

    I've got a 640Gb disk, am using about 150Gb, and TM usage is only about 130Gb after 6 months. Use is mainly photos and music and few files get edited more than 2 or 3x times. OTOH, if I was editing huge video files, I might have easily filled up the TM disks by now.
  4. Mr.Bullitt macrumors regular

    May 15, 2009
    I am a bit in the same situation.

    I have the 500GB drive in my MBP and I have a "spare" 500GB WD 7200rpm 16MB S-ATA drive from my desktop PC that I would like to "recycle" as a TM disk.

    I assume that you will have a choice of folders etc. to include and exclude for TM?

    Is any compression used on the TM drive???

    Will the difference between Firewire and USB 2.0 be notable for TM? (USB 2.0 housing are a lot cheaper to come by than Firewire ones)
  5. dXTC macrumors 68020


    Oct 30, 2006
    Up, up in my studio, studio
    I believe the general recommendation is at least 1x the size of the partition to be backed up-- more if you can afford it.

    For the OP, I would recommend a 400/100 split, unless you REALLY need the space available to Windows. My iMac (see sig) has a 250 Gb HD with a 160 Gb OSX partition and a ~64Gb WinXP/Bootcamp partition. My external, also a 250, has ~155 Gb dedicated to Time Machine, ~50 to Mac-only extra space, and ~30 to a FAT32 partition for both XP and OS X. I'm looking to upgrade to a 500 Gb or 1 Tb, as both my Time Machine and OS X extra space are pretty much filled up. Even so, I can still go back in Time Machine to about April 2008, so Time Machine is a rather efficient backup system when configured correctly.

    The Time Machine Preferences panel has a button that opens up a list of drives/folders to exclude. You can edit that to your liking. I would strongly recommend excluding folders for VMs (virtual machines). Anyone who is a heavy BitTorrent user should also probably exclude torrent download folders, as those files are written to in small increments.

    FireWire (400) is faster than USB 2.0 for sustained throughput. With smaller files, they're about even.
    FireWire 800 is MUCH faster than either of these. My external drive is on FW800, and Time Machine is extremely quick as a result.
  6. Wheaty macrumors regular


    Mar 6, 2009
    Cheshire, UK
    bucking the trend..

    I'm obviously bucking the trend then..

    I have my old 40GB drive from my PC (now HFS) backing up the valuables on my Mini..

    So Its only doing my work stuff and home Data (documents and pictures). I have set it not to back up any OSX installed applications, or music (I have all the CD's) which leaves me with about 32Gb of Data to save. Mainly photos.

    I would recommend a substantially bigger drive, I plan to get one. But pennies cant justify it at the moment for me (well justify what I would like more to the point!).

    My point is, that If your really picky about what you MUST back up then you can save to a smaller drive if needs must.

  7. 2Bad4U macrumors member


    Oct 31, 2009
    Atlantic Canada
    I'm new to Mac and I'm getting killed by my VM (Fusion). Can someone please provide me the path I should exclude in TM. The VM was stored in it's default location. Thanks in advance!

    -- Bill --
  8. r.j.s Moderator emeritus


    Mar 7, 2007
    It should be in ~\Documents\Virtual Machines\
  9. 2Bad4U macrumors member


    Oct 31, 2009
    Atlantic Canada
    That was quick... THANKS !!!

    -- Bill --
  10. sweetie81 macrumors regular

    Sep 13, 2007
    I wouldn't use it for regular use and a back up drive. THE MTBF time will come sooner than you might think and the risk of a hard disk failure due to heavy use might increase over a drive that would only be used for back ups.

    I would strongly recommend a solely hdd for back ups and for no other use than that.

    Now you can argue that I'm too careful but it's a back up in the end.

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