External Hard Drive question

Discussion in 'MacBook Pro' started by IBeDrummin, Aug 10, 2013.

  1. IBeDrummin macrumors member

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    Jul 24, 2013
    #1
    So I have an external hard drive that I use as a time machine backup for my iMac. However, I recently got the 256 gb (or how ever many) 15" Macbook Pro with retina and I will need an external hard drive for that. Not only for Time machine, but for story movies and stuff on it. Is it possible to use the same external hard drive from my iMac and not use Time Machine? What is the best thing for me to do?
     
  2. yusukeaoki macrumors 68030

    yusukeaoki

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    #2
    Just turn off TimeMachine and use it as a external drive...
     
  3. IBeDrummin thread starter macrumors member

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  4. Ledgem macrumors 65816

    Ledgem

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    #4
    I would strongly recommend that you have a Time Machine backup going for all of your systems. This is one of those things where if something goes wrong you'll be kicking yourself for turning it off.

    If getting another external drive is out of the question, you can always partition the drive. Time Machine technically only needs to be the same size as the drive that it is backing up, so you can partition your hard drive to have one partition of your iMac's hard drive, one partition for your MBP's hard drive, and then use the rest of the space as free storage. The Time Machine partitions will fill as Time Machine does its thing, but they won't grow to take over the entire drive.

    It's worth noting that limiting the size of your Time Machine volume will result in backups being culled more excessively. You'll still have your primary backup in place, but you won't have as long of a history of your files to recover from as compared with if you give Time Machine more space.
     
  5. Fletchwood, Aug 28, 2013
    Last edited: Aug 28, 2013

    Fletchwood macrumors newbie

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    Aug 28, 2013
    #5
    noob alert----

    "...partition the drive. Time Machine technically only needs to be the same size as the drive that it is backing up, so you can partition your hard drive to have one partition of your iMac's hard drive, one partition for your MBP's hard drive, and then use the rest of the space as free storage..."

    How does one partition the drive?:confused:
     
  6. Yahooligan macrumors 6502a

    Yahooligan

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    Illinois
    #6
    You don't need to partition the drive to use it for both Time Machine and as data storage, nor does each Time Machine instance need its own partition. A single drive of however many TB can have 1 partition and be used as a Time Machine destination for more than one Mac as well as used as general storage. Splitting the drive up into 2-3 partitions doesn't do anything but split usable space up into separate areas and make things more complicated.
     
  7. KUguardgrl13 macrumors 68020

    KUguardgrl13

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    #7
    +1

    I have a 1TB drive with backups for my MBP and compressed files I want to hang onto but don't need all the time.

    It worked perfectly for my 160 gb hard drive for Time Machine as well as storing this files. I just had my HDD replaced with a 500gb drive, so I may need to rearrange soon.
     
  8. scbond macrumors 6502

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    Oct 16, 2010
    Location:
    Nottingham, UK
    #8
    Yes you can use it as both an external storage and Time Machine disk, either by partitioning and creating separate parts for storage and backups or keep it all in one place. All Time Machine does is create a folder for the first machine and a disk image (.dmg) containing the same sort of folder for subsequent machines.

    I have an external hard drive connected to a Mac mini and then I connect to the mini wirelessly with a MBP and keep backups for both and storage for media files.
     
  9. Agent-P macrumors 68030

    Agent-P

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    #9
    This is true if you are only dealing with Macs (as the OP is). I needed to create an exFAT partition on my external that way I could use it between my MBP and Windows computer.
     
  10. Ledgem macrumors 65816

    Ledgem

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    #10
    The reason for creating the partition isn't out of necessity, but for user convenience. I mentioned the reason in my original post, but it was a sentence ending a paragraph. Basically, Time Machine grows its backups to fill the free space available on the partition. It doesn't fill up immediately, since Time Machine culls its backups, but it is ever-growing. You can't go and prune the backups yourself, either. Time Machine reaches a "steady state" once it fills up the hard drive, deleting the backups itself.

    In other words, you may start out with your backups and enough space for your other data, but eventually you'll find that you have an unknown quantity of free space for your stuff. The drive will be filled, and you'll delete things only to find that Time Machine has filled in that free space.

    You can avoid that scenario by creating a partition for Time Machine. The backups will then grow only to the size of the partition, and not to fill the entire drive.

    This is also why I suggested using Time Machine partitions for each computer. It isn't required, but Time Machine on one computer will not prune the Time Machine data from another computer. If the iMac has tons of data and backups, that leaves very little space for the Macbook Pro's backups. The backups will still be made, but the Macbook Pro will be forced to prune aggressively to maintain backups while the iMac will have much more space on the drive. This isn't critical, but it's not a scenario that you necessarily want. Creating separate partitions gives you control over how much space each machine receives for its Time Machine backups.

    It's all about personal control.

    Apple has a support document on the process. See the sections "Create new partitions on a disk" or "partition a non-startup disk" for the steps involved. It isn't difficult, but be aware that the steps used in "partition a non-startup disk" will erase the data on that disk in the process; "Create new partitions on a disk" will not.
     
  11. Yahooligan, Aug 29, 2013
    Last edited: Aug 29, 2013

    Yahooligan macrumors 6502a

    Yahooligan

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    #11
    You can always limit the size of the sparsebundle, then Time Machine will only grow to the size defined for the sparsebundle and not the entire drive. This avoids partitioning, resizing partitions, etc.

    First, after Time Machine is set up and the first backup done, switch Time Machine off.

    Then run the following commands as root (or via sudo)

    # hdiutil resize -size 950g /Volumes/path/to/sparsebundle
    # chflags uchg /Volumes/path/to/sparsebundle/Info.*

    Now turn Time Machine back on.

    That would set the size of the sparsebundle to 950GB and Time Machine backups won't exceed that, you now have put size constraints on Time Machine without going through the mess of repartitioning and wondering if any of the partitions will have enough space, if you need to adjust the size down the road, etc.

    I try to avoid creating multiple partitions whenever possible because it's much more convenient to have large spaces available instead of a lot of smaller ones.

    EDIT: I should add that this only works if your Time Machine is using a sparsebundle, such as when connecting to a remote disk that's connected to another Mac, Time Capsule, etc. A locally-connected external drive doesn't do this and partitioning is the only way I know of to limit how much space Time Machine uses.

    EDIT 2: I should also add that with local TM disks you can simply go into the disk and manually delete older backups just as if you were deleting any other folder, you don't HAVE to let Time Machine manage its space usage on its own.

    So, technically speaking, there is no case where Time Machine simply has to run until the disk is full and, back to my original point, partitioning is not necessary.
     
  12. blueroom macrumors 603

    blueroom

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    #12
    You could also consider using a small NAS like Synology makes.
     
  13. Ledgem macrumors 65816

    Ledgem

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    #13
    Modifying Time Machine's files through the Finder is not recommended (and it's a bit of a pain to navigate). I would believe you if you said that it could be done without corrupting anything, but it's something that I would strongly advise against doing for the majority of users.

    As to partitioning vs. keeping one partition with large amounts of space, I agree that larger spaces are more convenient than smaller ones if you're using them for your own data. However, Time Machine space (backups) are critical, and whether you limit the size of the sparse bundle or use partitions, that's space that you're not using for your own data. Thus partitioning it really isn't a major inconvenience; it's space that you've set aside for backups, which you ideally won't be interacting with through any means other than Time Machine. The potential threat of the sparse bundle solution is that your own data will fill more of the drive, leaving Time Machine with too little. You wouldn't know this unless Time Machine threw an error, or unless you routinely monitor your disk space.

    I think that partitions are a clean solution that are easy to set up, visualize, and modify if needed. If you're comfortable with the Terminal and have Time Machine set up to work through sparse bundles then it's nice to have that option. It seems like a more complicated hassle to me, but to each his own.
     
  14. Yahooligan macrumors 6502a

    Yahooligan

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    Illinois
    #14
    There is no issue of corruption when deleting old backup directories via Finder. You can even use "tmutil" to delete them if that makes you feel better, but the backups are nothing more than snapshots.

    Using Finder is actually the safest way as it won't allow you to delete anything you're not supposed to. The corruption concern is only a concern if someone were to mess with the Backups.backupdb directory itself, not the individual snapshot directories that are called out by date.

    Using "tmutil" is a bit more involved but the option is there.

    In any event, deleting Time Machine snapshots is well documented on the Internet and I've yet to see anyone cry foul. So don't just take my word for it, go forth and search. :)

    There are many ways to skin a cat, mine is but one and nobody should experience any issues by using this method. No need to "What if..." it to death. :D I'm sure the OP will choose whichever method suits them the best or whichever one they're most comfortable with.
     
  15. Mr. Dee macrumors 65816

    Mr. Dee

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    Jamaica
    #15
    Partitioned External HDD with Windows Backup

    Say you have a large 3TB External hard disk.

    You have two computers.
    - 1 Windows PC
    - 1 Mac

    Can you partition that external hard disk into three logical partitions and have:

    1 partition for Windows Backup and Restore/System Images
    1 partition for Time Machine on OS X
    1 NTFS partition just for copying files to
     
  16. Ledgem macrumors 65816

    Ledgem

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    Hawaii, USA
    #16
    Yes, but with a potential caveat.

    When you initially format the drive, the partition table will have to be GUID (Intel Macs; Windows identifies this as "GPT," for "GUID Partition Table") or MBR ("Master Boot Record," for legacy DOS/Windows). Which one you choose will have some ramifications on what you can do with your drive.

    From the Mac side, this is fairly simple: if you go with the MBR partition table, you will not be able to boot from the drive. Starting around OS X 10.7.2 (or 10.7.4?), Time Machine backups became bootable. It's not that you could boot into OS X from them, but you could boot from the drive and have the options to run some system utilities or to restore your system from the backup. It essentially externalized the "recovery partition." If the drive is formatted with the MBR partition table then you will be able to use Time Machine to backup, and to restore data from those backups, but you will not be able to boot into recovery mode from your Time Machine disk. Thus, GUID is ideal for the Mac.

    From the Windows side, based on what I've read, Windows XP (32-bit) does not support GUID; Windows XP 64-bit and later versions of Windows should, though. You will also need a motherboard that uses EFI instead of BIOS in order to boot from a drive formatted with the GUID partition table. I don't know much about Windows' backup mechanisms, so I can't say whether potentially being unable to boot from the drive is a bad thing or not. Lastly, I've read some comments from users that MBR is more widely supported that GUID ("GPT") for Windows programs, but a Microsoft support document indicates that "GPT" contains elements to provide support for legacy programs that expect MBR. I don't know how big a deal that is.

    One final consideration is that MBR maxes out at 2.2 TB. I've read some conflicting opinions about what this means; whether it means that MBR can only handle disks of 2.2 TB, or if it can only large disks but only partitions of 2.2 TB or smaller.

    Let us know what you choose and how it goes.
     
  17. scbond macrumors 6502

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    Nottingham, UK
    #17
    Why not just install Apple's HFS+ drivers for Windows?! I just have a 2TB external in one partition with two Macs backing up via Time Machine and then both Macs and my Windows PC using it for media storage.
     

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