Is it possible to run OS X on two seperate internal drives?

Discussion in 'Mac Pro' started by AppleWorking, Mar 21, 2009.

  1. AppleWorking macrumors regular

    Jan 20, 2009

    I want to install Leopard on two internal drives in my 09 MP. Is this possible? One copy on my drive in bay #1 and one copy on my drive in bay #3. One I will use to test out software and basically goof around with, the other copy will be used for my work. I figure this way I won't mess up my first drive that I use for work, whereas the copy I have in drive bay #3 can get as messed up as it wants to. :) Will this cause any conflicts at all? Will I be able to boot into either one? Will the two exchange files, or use the same settings and configurations, etc.? Or will they leave each other alone and run independently?

  2. bozz2006 macrumors 68030


    Aug 24, 2007
    yeah it's possible. just put an empty drive in, partition/format it. then use superduper or carbon copy cloner to clone your boot drive. then, just pick which one you want to boot into automatically. when you want to boot into the other one, just hold the "option" button you boot up your machine, and you can pick the "other" drive.
  3. h.21 macrumors member

    Nov 6, 2008
    When I have multiple copies of the OS installed using my Mac Pro, I usually boot into the Main OS that I will be using for my work. In the Spotlight prefs I tell it not to search any of the other drive's Apps/Utilities folders. This why if I search for "Terminal" I don't have to deal with different versions and copies cluttering up my list. I know I can hit enter and the version on my boot drive will launch.
  4. Lucibelle macrumors member

    Mar 12, 2009
    Having more than one OS on multiple drives or partitions is not only not a problem, it's actually a good idea. This way, should anything ever happen that prevents you from booting from your main drive, you can boot from your second drive. If the drive is new/blank, you may also want to consider partitioning the drive using Disk Utilities. This gives you multiple 'drives' within the drive, any of which can have OSX installed on it. If you format a partition with MS-DOS, you can use it for Windows.

    Partitioning basically turns one large drive into several smaller ones. Each partition looks and behaves just like a normal drive, and you can transfer files between them. One advantage of partitioning is that should your drive suffer a failure, it should only affect the partition where the problem occurred. For example, lets say you divide a drive into 4 partitions. (you can customize the size of each partition, or use the default, which divides them equally) You have installed OSX onto partitions 1 and 2, leaving 3 and 4 for files and/or backup. You normally boot from partition 1, when it unexpectedly fails and you can no longer boot from it. Depending on the type of failure, it is very likely that partitions 2, 3 and 4 are fine, letting you boot from partition 2. Now, You can run Disk Utilities, or any commercial hard drive utility you may have. Had the drive not been partitioned, the entire drive would have failed. FYI, your Mac will automatically boot from partition 2 if it is unable to boot from partition 1.

    You can still lose an entire drive that is partitioned, but unless the drive suffers from certain hardware failures, this is unlikely. It is always a good idea to backup and identify the problem quickly during any kind of hard drive failure, even if it only affects one partition.

    Another use for partitions is for backups. Let's use the same 4 partitions as above. If you boot from partition 1, you can have Time Machine back your files onto partition 3, providing extra protection should partition 1 (or 3) fail. You could also use partition 4 to backup 2 in the same manner.

    To be even safer, you can use Time Machine to backup onto another actual hard drive, which can also be partitioned. There are countless ways to set this up, but let's say you have 2 hard drives, each having 2 partitions. You can have OSX on partition 1 of each drive, then have Time Machine use partition 2 of the other drive to backup in a criss-cross manner. This way, your files are protected should either drive suffer from a partial or total failure.

    One last benefit to multiple boot drives/partitions is that once in a while, an update can be buggy or even render an application temporarily useless. One example is how the latest Quicktime update affected several games under OSX.4. The games that were affected could not be used at all, and you had to either wait for a patch from the game's developers, or use an earlier version of Quicktime. Quicktime cannot be uninstalled or reverted to an earlier version, so this was a major pain for several people. However, so long as the OS on partition 2 had not been updated yet, partition 2 could be still be used to run these games. This is just one example, but most any app could be affected this way by an update, especially third party apps. It has also been known to happen when upgrading to the next full version of OSX. This is also where it is GOOD that the OSs run independently, answering your other question.

    It is important to know that partitioning a drive WILL ERASE IT, so either start with a new drive, or backup/clone the drive before partitioning it. I know it's a lot to digest, and I hope haven't confused you, (and please forgive if you knew any of this already) but you can also search "partitions" in the Finder's help menu.
  5. MaCnation macrumors newbie

    Jul 10, 2009
  6. hyram macrumors regular

    Jun 15, 2009
    As others have stated: yup it's possible. I currently have 5 different startups on my mp...
    2 for SL like you want to do on disks 1 and 2. I ues exactly like you want to: one for business, one for fun.
    1 for tiger on disk 3 (I migrated from tiger to SL, I like to keep the old system around for a while to make sure I din't lose anything).
    1 for windows7 and 1 for freedos, both partitioned on disk 4.

    You can do what Bozz says and use the "option" key to select. I've been using rEFIt which works well but has a little twitch on the windows/freedos drive but is not a problem. I've never used bootcamp but I'm sure that would work as well.

  7. twstokes macrumors newbie


    Dec 30, 2008
    I would highly suggest never to make a backup of anything on the the same physical drive.

    I partitioned my Macbook Pro recently as I've been testing out Snow Leopard, and wrote an article on my blog on how to keep other partitions from automounting when you boot into an installation. This way your installations have no clue that other ones exists (unless you manually mount them) and keeps them completely separate.

    This may help
  8. UltraNEO* macrumors 601


    Jun 16, 2007
    Separate drive? Sure!! But you could have two different versions of the OS installed on one drive with two partitions.
  9. hyram macrumors regular

    Jun 15, 2009
    twstokes... Thanks! Great tip!

    I'll give it a try as soon as I can.
  10. gugucom macrumors 68020


    May 21, 2009
    Munich, Germany
    Athough this is basic wisdom one has to add that modern systems like disk utility starting from Leopard will let you do some partitioning work without erasing data. Whenever you see the little triangle in the lower right hand corner of a partitioned drive in the partitioning GUI you have the opportunity to resize a partition without destroying data. Same goes for the little dot between partition blocks. It indicates you can drag it up and down to change the distribution of disk size between partitions. :cool::D

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