2 Replies Latest reply: Aug 19, 2013 7:13 PM by Christopher Murphy
Kiggavik Level 1 Level 1 (0 points)

I run a MacPro 2X2.8 Quad Core, using OX 10.8.4.


I have two WD Caviar Black 1TB Drives set up as a mirrored (RAID 1) RAID.  It is now full. I've just installed two WD Caviar Green 3TB drives as another Mirrored (RAID 1) RAID.


My question is can I set the two RAID sets up as a concatenated volume so it acts as one 4TB volume? Without losing the data already on the 1TB RAID?



Mac Pro, OS X Mountain Lion (10.8.4)
  • Grant Bennet-Alder Level 9 Level 9 (54,350 points)

    Without losing the data already on the 1TB RAID?



    It will not do this re-configuartion without dumping your data. To proceed, make two independent Backup sets in case one fails.




    Green drives are not the best choice for performance, but they make GREAT Backup drives.

  • Christopher Murphy Level 3 Level 3 (555 points)

    No, the linear concat already needs to have been created for the first array set to have the proper metadata, from that point it's possible to grow the array just by adding arbitrary sized mirrors to the concat array, then growing the file system.


    However, it is possible to convert an existing JHFS+ volume into a Core Storage Logical Volume without destroying the data on it, and also without enabling encryption via a Logical Volume Family. Next, you can create the 3TB mirror array, making it a Physical Volume, adding it to the same Volume Group as the first mirror, and then growing the underlying Logical Volume which will also grow the file system. I've also only done this with diskutil cs commands on command line, the Disk Utility GUI application doesn't have much of Core Storage exposed at all. The catch is, in either case, if two drives go in a mirror, it won't just take out that mirror, it takes out the entire file system. So you still must make regular backups.