DonCelian

Q: RAID 1 (LaCie) - Possible to Partition??

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

Posted on Aug 1, 2012 10:07 AM

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Q: RAID 1 (LaCie) - Possible to Partition??

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  • by Stephan-S,

    Stephan-S Stephan-S Jan 31, 2014 2:59 PM in response to gcortes
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    Jan 31, 2014 2:59 PM in response to gcortes

    As I was researching the matter of Partitioned RAID in anticipation of buying a Lacie 2Big (a 2nd one actually), I found this thread and decided I should make some tests to verify some assumptions mentioned earlier on here.

     

    I created a partitioned RAID setup with a Mountain Lion 10.8.5 virtual machine in VMware Fusion, and showed that both OS X and Disk Utility do support partitioned RAID setups as we would normally expect. Whether that translates successfully into a physical drives setup, I would expect so (but hadn't the opportunity to check to-date).

     

    [sorry for the French screenshots instead of English, but you should get the substance of it]

     

    Step 1 : initial setup of partitions. On 2 separate drives, I created 2 partitions on each : 1 partition that's intended for RAID 0 (first partition in what would be the fastest area on a physical drive), and another one that's intended for RAID 1. Same partition sizes on both drives. At this point, Disk Utility does format the partitions with jHFS+ because it won't create blank partitions, although the partitions will get reformatted anyway in the process of setting up the RAIDs.

     

    Initial partitions.png

     

    Step 2 : create the 2 RAID arrays. One is striped RAID 0 (simulated for performance - 2 x 5 GB = 10 GB), the other is mirrorred RAID 1 (for safer archives - 2 x 16 GB = 16 GB).

     

    RAID 0 screenshot.png

    RAID 1 screenshot.png

     

    Step 3 : simulate drive failure. I deleted a virtual disk from the virtual machine, as if the drive had failed and therefore was unavailable anymore to the operating system. I lost the RAID 0 volume as expected, but the RAID 1 volume is still there although in degraded mode. Its contents are unaffected and accessible as I can check in the Finder.

     

    RAID 1 - degraded.png

     

    RAID 1- Finder OK.png

     

    So, regarding LaCie Support's statements that partitioned RAID either isn't supported by OS X and Apple Disk Utility, or would cause 100% data loss in case of single drive failure, I find this inaccurate and instead fully functional. I can't see where the issue would be...

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