Time Machine help. I am confused.

Discussion in 'macOS' started by colonel179, Aug 18, 2015.

  1. colonel179 macrumors member

    Jun 10, 2014

    I recently received a 2TB external HDD (Seagate) for my office, and I wanted to know exactly how Time Machine works. I assume it works like iOS backups, in the way that, when you restore your iPhone from an iCloud backup, the phone would be restored EXACTLY as you had it before it.

    However, my doubt is that, if that's the case, why would I need a bigger HDD than my Mac currently has (250 GB SDD). My thinking is that if my Mac has 250GB, Time Machine will only be able to backup 250GB, since that's the most I can put in my Mac. Is that the way it works? The reason I ask is because I don't know how to partition the HDD so I can have the Time Machine Backup and other to use it as a normal USB storage device (exFAT).

    Also, I have these three questions:
    - Can you back up only files and not OS system files, etc?
    - Can you do automatic AND manual backups? Will they interfere with each other; like, would they be separate?
    -When EL Capitan launches, how would that affect my Time Machine backups, as I will most likely do a clean install?

    Thank you very much. I have never used Time Machine, and I don't want to mess it up. My Macbook Pro is new, so I would like to start with backups from the beginning
  2. Weaselboy Moderator


    Staff Member

    Jan 23, 2005
    Time Machine needs more space the the amount of data on the source drive because it saves "versions" of files and also saves anything you may have emptied into the trash.

    For example, if you update a spreadsheet one a day with new info then save it. TM will keep each days version in its backup set. So if you wanted to go back and retrieve the saved version from last Friday, you could.

    Also, say you download a 2GB video from the Internet and that gets backed up to TM. Then you delete the file and empty the trash. That 2GB file is going to stay in the TM backup so you can go back and retrieve it if you like.

    Time Machine will keep on saving all these file versions until the target disk starts to get full, then TM will start to purge off the oldest data.

    TM is designed to backup the entire drive, including the OS and all your data. That way it can be used as the source for a full system restore say if you ever had to replace your internal drive.

    By default TM will backup once an hour. You can click and do a manual backup in between if you want and it will be part of the same backup set.

    You can make two partition on the drive and use the Mac OS Extended partition for TM and the ExFAT partition for swapping files with Windows if you want. Just be aware those files on the ExFAT partition are not being backed up anywhere. Normally, you would want to make the TM partition about twice the size of the source volume to allow room for the versioning I mentioned.

    When you update the El Capitan, you don't need to do anything. The same TM backup set will just keep on running. That first backup after the update will be large due to all the changed system files, but it will just keep on going.
  3. Ebenezum macrumors 6502a

    Mar 31, 2015
    If you have important information on your Mac that you can't lose I recommend making regular clones to another external hard drive with Disk Utility, SuperDuper or Carbon Copy Cloner.

    Restoring clone is much faster compared to full Time Machine restore.

    I am not saying you will have problems with Time Machine but relying on it without other backups is bad idea with important information!

    Example: http://joeontech.net/why-i-dont-rely-on-time-machine.html
  4. Taz Mangus macrumors 68040

    Taz Mangus

    Mar 10, 2011
    Yes you can have Time Machine only backup the user account files by excluding the OS files from the backup. You will want to have some sort of backup of the system in case you need it for a reinstall situation.

    I use this type of scenario. I have a external hard drive attached to my iMac where automatic backups happen every hour when the computer is awake. I also use a second external hard drive that I plug into the iMac and do a secondary manual backup with Time Machine. It is always a good idea to have at least 2 backups of your user data, in case of fire or the backup hard drives fail.

    You should be able to restore your user data after a clean install. I suggest that you don't restore any OS system files unless they are specially from 10.11.
  5. colonel179 thread starter macrumors member

    Jun 10, 2014
    Thank you very much for your responses. I got a better understanding now, and I setup Time Machine and it was all good. I am very thankful for the help and time you took to respond.

    "You should be able to restore your user data after a clean install. I suggest that you don't restore any OS system files unless they are specially from 10.11."

    After a clean install, how would you decide that only user files should be restored?
  6. Fishrrman macrumors G5


    Feb 20, 2009
    I second Ebenezum's post #3 above.

    Don't waste time "trying to understand" Time Machine.

    Use either CarbonCopyCloner or SuperDuper to create a fully-bootable cloned backup of your drive, instead.

    It will appear "as identical" on your desktop, because it is -- a true "clone" of the internal drive at the moment the backup was created.

    All your files will be there, in plain-old-finder-format.

    And it's fully bootable to the finder, as well.

    CCC will even clone over your recovery partition.
    And CCC can archive older versions of files, just as TM does.

    My opinion only.
    Others will disagree.
    Some will disagree vehemently.
  7. aristobrat macrumors G5

    Oct 14, 2005
    It's part of the Setup Assistant that runs on a clean install. One of the first few screens asks if you want to restore user data from a Time Machine (Time Capsule) backup.
  8. colonel179 thread starter macrumors member

    Jun 10, 2014
    I don't need to clone my disk since I have no use for it. This is something we do a lot with Windows machines though. People want everything as they used to have. Nevertheless, thanks for the suggestion.
  9. chown33 macrumors 604

    Aug 9, 2009
    Sailing beyond the sunset
    This isn't how Time Machine works.

    Time Machine makes a series of backups. Each backup is capable of restoring to that point in time. Hence the name "Time Machine", since you are then able to go back to any previous point in time (that has a backup) and restore all or part of what existed at that time.

    If there were only one point in time to go back to, i.e. the most recent backup, then the backup disk would only need to be as big as what's being backed up. However, since Time Machine makes a series of backups, every file that changes at any point will need to be backed up. Time Machine knows not to duplicate things that didn't change, but if a file changed 30 times over the course of a week, then there will be 30 different backups of that file, each one a "snapshot" of that file at that point in time.

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