Here is my current situation:

Mac Pro Server with 1x normal OS drive and 2x 750Gb data drives in a raid-1 configuration. I'm starting to fill up the space on the data drives and would like to replace the array with a set of 2Tb drives. There are only three SATA ports in my system and they are all in use with the three drives.

I'm hoping that I can replace one of the 750Gb drives with a 2Tb in the raid-1 array. Wait for the array to repair and then replace the other 750Gb drive. Then expand the 750Gb array to a 2Tb array.

Has anyone tried something like this on Mac OS X?


That's not going to work. What I would do: Put one of the old drives into an USB or firewire case, replace the disks in the system, create a RAID and copy the data from the USB drive.

Also, are you talking about a MacPro or an Xserve? The former has four SATA drive bays.


OS X can expand volumes, but as far as I know there's no way to expand a RAID set. What I'd do is remove the two 750GB drives and install the new 2TB drives, and configure them as a RAID set. Then remove one of the 2TB drives and install one of the 750GB; this gives you access to both RAID sets (although obviously degraded to only one drive each). Next, copy the volume contents from the old RAID to the new one (Disk Utility's Restore tab with the erase option selected is a good choice for this). Finally, remove the 750GB drive, install the other 2TB, and force the RAID to resynch.

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