Currently Being ModeratedDec 18, 2012 10:39 PM (in response to Christopher Murphy)
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.
Currently Being ModeratedDec 19, 2012 12:07 AM (in response to gcortes)
I'm a little unclear on the advantage of partitioning for this use case. If you want a separate file system for Time Machine, while that's a good idea, it can be done by creating a sparse bundle disk image, which grows as needed.
Currently Being ModeratedDec 19, 2012 5:47 AM (in response to Christopher Murphy)
I’m a little confuse, can we or not partition a level 1 raid?
What about —>
Normally you mirror entire drives and just drag into the window. If, instead, you want to have multiple mirror volumes, or mirror and standard:
Create two partitions on each drive that are identical (the drives really should also be same make/model/firmware)
Drag "A1" and "B1" into the RAID setup window.
Then you still have A2 and B2 that you can leave, or combine into RAID set.
Apple does have tech note on how. The whole thing is much easier and can be changed easier if you were to buy SoftRAID.com product. It also offers "stripe reading" for mirrors to improve performance.
Most people use two drives but having three drive mirror has added redundancy in case of failure, and you can break one drive off for backup storage and still have two drives.
Currently Being ModeratedDec 19, 2012 12:52 PM (in response to gcortes)
Well, LaCie poured cold water all over the method:
This method will reduce overall performance of the unit. It also results in a configuration that means that if a single drive mechanism fails, you would likely loose all information on both drives; essentially defeating the purpose of having RAID1 in the first place.
As a result, we do not recommend or support using the unit in this configuration.
I don't why it should cause the problems described, but I'll take their word for it.
Currently Being ModeratedDec 19, 2012 2:02 PM (in response to gcortes)
In any case I would test it. If Apple is allowing you to produce a configuration of two RAID 1 partitions, something which is allowed on Linux and survives just fine (I have tested that a lot), then it's a huge bug. Either it's a bug in the GUI for allowing it; or a bug in the underlying implementation. So I'm skeptical, I think it just means they don't want to support it.
Unfortunately as I think about it, Apple's boot loader doesn't know what Core Storage is, and they also don't put the boot loader on the EFI System Partition either. So in either case, you wouldn't be able to boot from a logical volume. That's a drag as it's been possible to do this on Linux also for something like 6 years.
But I'm not understanding your use case for wanting to boot from a Firewire drive anyway. For an emergency, OK, but I think you can do this from even a 2GB flash drive made with Recovery Disk Assistant.
Currently Being ModeratedDec 20, 2012 3:52 AM (in response to DonCelian)
What about SoftRaid (They tell me that their software will do it easy) and just bypass Disk Utility?
I think that this type of backup is absolutely basic and a minimum in security. If Apple don’t have the ability to do it, it show sadly that their software is not ready for business use....
Really sad for a company that pretend to be Innovative....
Currently Being ModeratedDec 20, 2012 10:08 AM (in response to Chacapamac)
A Time Machine backup to RAID 1 is not basic. It arguably gains you very little in security. Instead of one Time Machine backup to RAID 1, your'e vastly better off with two Time Machine backups to two drives. For a business that is basic. Time Machine backups get corrupted, and once corrupt, both "copies" in a RAID 1 array are corrupt.
And besides, this is innnovation in the consumer device world right now. Apple hasn't been in the enterprise or storage business for years.
What you could do is partition the two drives the same, and mirror just one partition on each drive. The unmirrored partitions on each drive, you can use for alternating Time Machine backups. Or you can use one of them for Time Machine backups, and the other one for a bootable Carbon Copy Cloner type of backup. Two different kinds of backups on two disks, one of which is bootable.
Currently Being ModeratedDec 20, 2012 12:36 PM (in response to Christopher Murphy)
I copied files to both partitions without problems. I then copied a 95GB directory and I didn't have any problems with it either. I suspect it probably will work fine and LaCie is just being cautious.
I decided to go back to the single partition because the use case for having a bootable backup partition were it possible doesn't buy me much. The goal was to be able to be back up running should the SSD (OS and apps) fail. As I understand it, SSD failures are usually catastrophic so I would have to take the Mac Mini in for repair. I wouldn't have a computer to boot. Since I will have all my data on the RAID, my plan is to connect to my Macbook Air if the Mac Mini fails. My applications are already duplicated across both platforms.
I also have a separate drive for my Time Machine backups in a fire and water proof enclosure (IOSafe) so my cofiguration is a bit overkill for a personal system. I spent years working with systems with RAED's (Redundant Array of Expensive Drives) and have lost a number of RAID drives on my Windows machines in the past so I error on the side of caution.
Currently Being ModeratedDec 21, 2012 5:32 AM (in response to Christopher Murphy)
Currently Being ModeratedJan 5, 2013 7:19 AM (in response to Chacapamac)
Ok I don’t think my new Sheme will work...
I guess all partition have to be mirror, they probably cannot be some mirror and some don’t...
In this case I will move one time machine backup with the first partition (Boot OSX, Windows, Stuff, Time machine 1 and leave a single Time machine patition alone that will mbe mirror...
Now The REAL question : Is this working or not and if the use of software like “Softraid” can work?
Currently Being ModeratedApr 30, 2013 7:18 AM (in response to gcortes)
I just created a similar setup, but did it with Western Digital Thunderbolt Duo 4GB.
I created 2 RAID sets. They both work fine.
But performance wise, the bigger one performs at twice the speed.
Same RAID type. Same filesystem.
I have no idea why!