RAID 1 (LaCie) - Possible to Partition??

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.

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 :-)

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?

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.

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....

Thank’s

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.

Thank You Christopher - Appreciate 🙂

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

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).

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....

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.

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.

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.

LaCie confirmed that it's not possible:

The Apple Disk Utility does not allow a software RAIDed volume to be split into multiple partitions. This is not a limitation of the 2big itself, it is a limitation imposed by Mac OS X and the Disk Utility application.

I had planned on creating a separate partition for a back up image of the main SSD like the OP.