Booting from an OSX internal raid

February 12, 2006 11:06 AM

I want to boot my Mac G5 from an internal striped software raid. Possible?

• Dual-core 2GHz G5 running OSX 10.4.4;
• Total of two internal SATA 300 drive bays, one of which currently holds the internal WD SATA 160 that came stock.

I want to install two 500 GB drives and set them up to boot as a striped 1 TB drive. I plan to back it up with three 320 GB USB2 Fantoms.

In both setups, I want to use OSX's software raid functionality, but I don't know if I can. I have successfully stripe-raided two and three external drive combinations, and the speed increase is significant. I want to exploit the speed advantage of the internal SATA 300 architecture by raiding internal drives, but I don't know if OSX will boot from its own raid, let alone an internal raid.

If it is possible, what steps should I take to set it up? Move my boot drive to an external case and boot from that when I set up the two 500s? Can G5s boot from external drives?

posted by squirrel to computers & internet (2 comments total)

I believe the most common solution is to use SoftRAID to create bootable RAID volumes, but as far as I know it only supports using RAID-1 (non-striped, mirrored) volumes for startup (though I may be wrong about that).

Apple's RAID-0 volumes are not bootable.

Yes, Macintoshes can boot from external devices.
posted by majick at 11:12 AM on February 12, 2006

Squirrel, I would recommend creating two partitions on each of your internal drives. A small raid 1 partition that contains your system and which you boot from, and a large raid 0 for the rest of your data. Make sure your swap file is on the raid 0.

It's a shame that OS X doesn't give you more control over your layout, since really you want the read only stuff (in plain unix parlance / & /usr) as raid 1, and perhaps the important writeable stuff (/home & /var) raid 1 also, but there's no reason to not have swap, /tmp and /var/tmp etc. as raid 0, except for ensuring maximum uptime.
posted by cytherea at 8:17 PM on February 12, 2006