Previous 1 2 3 Next 30 Replies Latest reply: Jan 31, 2014 2:59 PM by Stephan-S
DonCelian Level 1 (0 points)

Greetings Everyone!


I'm a very excited and happy new iMac owner (Mid 2011, 3.4Ghtz, i7, 8GB)...


I recently purchased a LaCie 4TB (RAID1, 2TBx2TB) 2Big Thunderbolt Drive for the following 2 purposes:


1) Create and Store a "Bootable Backup" of my  iMac hard drive.


2) Fast External Storage for all my family's media (RAW photos, Music, Movies..)


However, after much research (as well as some conflicting reports), I'm really confused as to the possibility AND advisability of creating a partition in my RAID1 setup.  I initially chose this Thunderbolt drive because of the "safety" of creating a mirrored RAID setup... however, according to the SuperDuper! user manual, it is STRONGLY recommended that any backup be partitioned or on a separate disk altogether from regular storage (i.e. Media).

Now, each time I go to attempt to partition my RAID set using DiskUtility it states in the partition info that "this partition can't be modified.  Changing a RAID partition may leave the RAID set unusable."   This statement frightens me and keeps me from proceeding past this point..

My LaCie 2Big does not support JBOD.  So, is it in fact possible to partition my RAID1 setup or am I stuck with no "bootable backup" on the external drive, in which case I'd be forced to save a bootable backup to DVD's (optical) or find some other alternative??


I should mention that I do have a Time Capsule running regular Time Machine backups, which from my understanding are not "bootable backups" or a clone...


Any assistance is VERY MUCH APPRECIATED, as I'm very eager to implement a decent backup system (including a "bootable backup") as soon as possible.

The LaCie is just sitting there empty in RAID1 right now until I can figure this out and proceed..


Thank you in advance for any help and guidance..

iMac, Time Capsule (Time Machine), LaCie
  • Camelot Level 8 (46,665 points)

    I think you're reading too much

    Or, at least, reading too much into different people's documentation.

    SuperDuper is a general-purpose data duplication application and any advice it gives can only be generalized. In this case what they're telling you is that you shouldn't back up your data to the same physical disk - and that just makes sense because if the physical disk breaks you lose both your data and the backup.


    But that's not your situation here.

    For one you're not creating a backup of your data on the same disk - you're creating a backup of your main system disk, plus a second storage location for media. So right there you can ignore SD's statement since it doesn't apply to you - or, more correctly, you are already complying with their suggestion.

    Secondly, SD doesn't know that what you're backing up to is a RAID volume, which has its own set of data protections built-in. Like I said, it's advice will only be general.


    So, in this case you should be absolutely fine to take that 2TB disk presented by LaCie and partition it in any way you want. The fact is that the LaCie has handling all the RAID 1 work, so even the OS isn't aware that the disk is mirrored, and that might be where the confusion sets in.


    In Disk Utility you should see two disks - your internal OS disk, and the 2TB LaCie (which is, in reality, two 2TB drives in a mirror config, but the OS doesn't know that).

    Go ahead and select the LaCie disk (not the existing partition(s)), then click the Partition tab.

    Set the number and size of partitions you want and you're done.


    Each of the LaCie paritions will be reasonably protected by the RAID 1 setup in the LaCie enclosure.

  • DonCelian Level 1 (0 points)

    Thank you very much Camelot!

    That's exactly what I needed to know..  I will attempt the partition this evening and see how it goes!


    In regards to the partition itself, do you think one partition of ~400GB is sufficient for my purposes of a bootable backup?

    My iMac hard disk currently has ~300GB worth of info on it...


    Thanks again for your speedy reply and all your help!

  • DonCelian Level 1 (0 points)

    Hello Camelot..

    I'm in Disk Utility and there are four items visible:

    1 & 2) the two partitions of the RAID

    3 & 4) the two disks (internal OS & 2TB LaCie)


    I select the 2TB LaCie RAID 1 disk, however it only shows the "First Aid" & "RAID" tabs. 

    The "Partition" (as well as "Erase" & "Restore") tabs are not available or shown.  The Internal OS Disk shows all the tabs and the two partitions of the RAID show the "First Aid, Erase, Partition, & Restore" tabs..


    As you stated, I'm not to select the partitions themselves (which do show the "partition" tab available), so, is there any way to make the partition tab show up for the actual 2TB LaCie Disk??  Am I missing some step??


    Any assistance is once again GREATLY APPRECIATED.  Thank you!

  • Davey Boy 66 Level 1 (0 points)

    Hi there DonCelian,


    I ran into the same issue as you, and contacted LaCie support - and they agreed with Camelot. You can partition the drive after setting up a RAID 1.


    You click on the first Slice of the RAID - then partition, and away you go... :-)




    All will be well according to the help guys at Lacie:




    Hope this helps...


    p.s. these images look fine on this Retina MBP before clicking "save", but afterwards look a bit grainy/blurry :-)

  • Christopher Murphy Level 3 (555 points)

    Umm, I find this very confusing. The physical disks are the two 2TB ST2000DM001-9YN drives. The partition type is RAID Slice on each disk. Those two slices are converted into a virtual disk, "the RAID" if you will, which is "2TB Lacie Raid". That is what you want to partition.


    Presently you see that it is already partitioned and formatted (which is the volume listed underneath, "Lacie Raid"). What you seem to want are 2 or more partitions (and thus JHFS+ or JHFSX volumes) underneath "2TB Lacie Raid".


    If you partition what the screen shot labels as "Partition this one?" you will obliterate that physical disks partition map claiming it is part of a RAID 1 set, and turn it into its own indepedent disk.


    This setup appears to be using Mac OS X software RAID. Not any sort of built-in enclosure RAID. What LaCie product is this?

  • Christopher Murphy Level 3 (555 points)

    Yeah I just read the 2nd screen shot, with the discussion with LaCie support. You need to partition the virtual disk "2TB Lacie Raid", not either of the physical drives with model numbers as your first screen shot shows an arrow pointing to. I think you confused his corrective statement with confirmation you are pointing to the thing to partition.

  • Chacapamac Level 1 (0 points)

    Really interesting,

    as I choose the same pattern and disk (LaCie) for the same purpose.

    • One bootable clone (Copy Carbon Cloner because I have Mountain Lion and I want to keep the Apple recovery partition) backup alone in one partition


    • and a bootable partition with Parallels and multiple Windows OS and storage space for big files.


    Should I have partition for each OS ??????


    How you guys find the lacie setup — I guess you using thunderbolt — can you give a small follow up to see how it went and if your satisfied....



  • Christopher Murphy Level 3 (555 points)

    Windows will not (natively) boot from an Apple software RAID. So no, you should not partition for each OS, you should create virtual disks within Parallels, install Windows to those virtual disks which of course like any file can reside on the software RAID.

  • Chacapamac Level 1 (0 points)

    Thank You Christopher - Appreciate 


    Can I still have a partition for my clone ? (maybe one for TimeMachine ?

  • Christopher Murphy Level 3 (555 points)

    You can but it's of marginal benefit to clone/backup a volume to another partition on the same RAID. To gain true redundancy you need to put those things on a different drive or array. If the RAID fails, your clone and Time Machine backup fail too. I would absolutely not consider it a viable backup unless they are on a totally separate physical drive (or array).

  • Chacapamac Level 1 (0 points)

    I’m not sure if you understand what I exactly mean.


    The Clone and TimeMachine partition will be of the IMac itself


    Something like that....


  • Christopher Murphy Level 3 (555 points)

    Generally partitioning wastes space because of how much headroom you have to add to each one. For Time Machine backups I'd definitely put them on their own partition because they regularly corrupt themselves and it's simply easier to reformat (erase) that partition, which gets you a whole new clean file system to start a new Time Machine backup from scratch. For other people's computers I tend to have two Time Machine partitions and alternate backups between them (say, once a week or once a month, switch partitions for backups). That way when I nuke a Time Machine partition I still have a backup. And I tend to blow them away after they reach 6-9 months age.


    I would reverse the partitioning scheme in the diagram. I'd put the bulk of your stuff on the first partition. And make the clone and or Time Machine partitions after that. This will make it a bit easier to resize them should it be needed (although the resizing capabilities of Disk Utility are much more limited than their CLI counterpart 'diskutil' use 'man diskutil' for more info and look for the resizevolume command. Be aware some resizing operations destroy data while others don't. Be really sure what you're doing.

  • gcortes Level 1 (5 points)

    I just got my LaCie 2Big today and tried to partition the first drive after setting up RAID 1. The partition works, but the drive is dropped out of the RAID. If I partition the second one, the RAID disapears. If I partition the drives first and then put them into a RAID, the partitions are erased. This is on Moutain Lion. I'm going to try LaCie support.

  • Christopher Murphy Level 3 (555 points)

    Yep, I'm finding it can't be done with the GUI. It might be possible to do this from the command line by first creating the RAID, and then adding that to a core storage volume group, then creating logical volumes.

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