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..
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.