Time Machine Backup Drive Size

Discussion in 'iMac' started by NZiMac, Sep 22, 2015.

  1. NZiMac macrumors newbie

    Joined:
    Feb 18, 2015
    #1
    Hi, I am a new Mac user, going great so far but have lots of questions. My new iMac Retina 5K has a 3 Tb fusion drive. I read that a backup Drive for time machine should be at least as large as the drive you are backing up. It will be years before I get anywhere near using the 3 Tb so do I need a drive that large i.e. Will it work with a smaller backup drive. I had also considered getting a larger drive and partitioning it, with one partition used to store Windows files. Would this work with Parallels or VM fusion? Thanks for your help.
     
  2. tillsbury macrumors 65816

    Joined:
    Dec 24, 2007
    #2
    No, you need the backup drive to be significantly bigger than the amount of data you're backing up. If you're only using 1Tb of your drive, a 2Tb external backup drive will be easily enough. I'd suggest buying a cheap external USB3 drive of 2Tb or 3Tb capacity.

    I wouldn't suggest "partitioning" this drive to use part of it as storage space. It's not a backup drive then, really. Parallels and Fusion can both use space on your main drive for whatever you want, and you can choose whether or not you back this data up along with your normal Time Machine data. I'd suggest having shared folders for data you want to use in both OSX and Windows, and not backing up your main Parallels virtual machines with Time Machine. Just take a snapshot copy every now and then when you have things on your virtual machine set up how you want.
     
  3. deany macrumors 68020

    deany

    Joined:
    Sep 16, 2012
    Location:
    North Wales
    #3
    Hi
    as long as you have backup parallels in Time Machine checked why do you say? 'and not backing up your main Parallels virtual machines with Time Machine.'

    I was hoping to backup my entire mac to TC inc. Parallels. Is this not a good idea/ because it is sooo convenient.

    This is what we do in the office (as well as three other backups inc off site)

    Cheers
     
  4. tillsbury macrumors 65816

    Joined:
    Dec 24, 2007
    #4
    You can, but every time you change anything in your Windows virtual machine the entire Parallels machine file changes, and Time Machine will copy the whole shooting match to your backup drive. This will take an age and clog up your backup drive. Better to either do backups in Windows. Or even better to do as I described -- set up the virtual machine as you want it, then take a snapshot (or copy the Parallels file and rename it) so you can go back to that setup at any time. Use data on virtual drives that are actually stored on OSX. Those files will be backed up by Time Machine continuously.
     
  5. deany, Sep 28, 2015
    Last edited: Sep 28, 2015

    deany macrumors 68020

    deany

    Joined:
    Sep 16, 2012
    Location:
    North Wales
    #5
    Hi Tillsbury

    thanks for your reply.

    I was wondering why we are having some issues with Time Machine backups to Time Capsule in the office.!

    We are quite new to osx.

    So if we turn off the backup to Time Machine in Parallels.

    Next we have one folder in Windows 7 we keep all files & folders (approx 30 GB the Outlook file is 5 GB), how would you advise backing up that? we have dropbox 1TB in W7 but could expand our icloud account or use dropbox 1 TB on the mac side.

    A message does come regarding parallels snapshot is that the same 'snapshot' you mention? is this by default saved on the mac side so is backed up in Time Machine. Is this setup best http://kb.parallels.com/en/115052

    I think I understand but would really appreciate a 'Dummies guide'.

    We have imacs 512 gb a 2TB TC, Yosemite, Parallels 10, W7, W XP, MS Office the folder in W7 is approx 30 gb we were using Time Machine Editor and backing up at night but its clogged up. I have had to erase via Airport Utility.

    We mainly use W7 and MS Office.

    thanks again
     
  6. tillsbury macrumors 65816

    Joined:
    Dec 24, 2007
    #6
    I would suggest that instead of having a 30Gb folder in Windows, you place that on the OSX drive. Then you use virtual drives in parallels to make a drive point to that data in Windows. That way you can still access it in Windows, but Time Machine will back up the data instead (as it's really in OSX). And you can access it from an OSX app should you wish to.
     
  7. colodane macrumors 6502a

    colodane

    Joined:
    Nov 11, 2012
    Location:
    Colorado
    #8
    To give an actual usage datapoint for the OP's question, here is my Time Machine disk usage for my iMac:

    I have a 256 GB SSD in my mid 2011 iMac and now, after almost 5 years of usage have a total of 67 GB of it used. I'm using a 1 TB hard disk drive for the Time Machine backup and now have a total of 107 GB of data on it after 5 years of hourly backups.

    This reinforces that the incremental update design that Apple uses is quite space efficient. Sizing the backup drive based on about twice the data ACTUALLY USED on the main drive is indeed a good rule-of-thumb. Even if the backup drive eventually fills up and starts deleting the oldest backups, I would not be at all concerned about losing some incremental backups that are over 5 years old.
     
  8. tillsbury macrumors 65816

    Joined:
    Dec 24, 2007
    #9
  9. deany macrumors 68020

    deany

    Joined:
    Sep 16, 2012
    Location:
    North Wales
  10. NZiMac thread starter macrumors newbie

    Joined:
    Feb 18, 2015
    #11
    Thanks very much for your replies, I appreciate it.
     

Share This Page