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User profile for user: rezwits
rezwits Author
User level: Level 1
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Can I Boot from a RAID 1 (mirror) in my G4?

I don't know where I read about this, but I am getting ready to redo one of my systems. Currently it has 2 identical 250GB Hitachies, which use Super Duper every Sunday to backup. I tried doing a RAID 0 back in like 2004 on a system that had 4x60GB. I found out through trial and error and then later reading that you can't boot from a RAID in a Power Mac G4. But like I said earlier I don't know where I read this, but someone stated I could boot from a RAID 1 (mirror) in my Power Mac G4. Is this true? or not? Is it possible to boot from a RAID 1 in a Mac G4 but not RAID 0?

Something tells me this isn't going to work. I have a 10% glimmer of hope that maybe it will just see the drive as a regular drive. This would really be great. If anyone knows the answer to this puzzle please feel free to let me know... thanks.

Laters...

MacBook, Mac OS X (10.5)

Posted on Oct 2, 2008 12:07 PM

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10 replies
User profile for user: japamac
japamac
User level: Level 7
24,400 points

Oct 3, 2008 6:13 AM in response to rezwits

Hi-

RAID as a boot volume is supported in systems with OS X 10.3 or later.
Mac OS X, Mac OS X Server: How to Use Apple-Supplied RAID Software

A mirror RAID is definitely a safer boot volume than a striped RAID. Still, you need to keep SuperDuper!, and get a third drive for backup of the RAID, unless you like living dangerously.

If your really serious about performance, but don't want to tempt the Gods, get a RAID card that supports a RAID 5. Then you have better performance and better hardware failure tolerance........
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User profile for user: Grant Bennet-Alder
Grant Bennet-Alder
User level: Level 10
126,985 points

Oct 3, 2008 6:56 AM in response to japamac

Server gurus love to remind us that mirroring improves UPTIME, but does not eliminate the need for BACKUP. Certain failures, including User Error, can still wipe out data.

Uptime is improved because a replacement for one failed drive can be added in, and then the mirrored array can be rebuilt in the background. Meanwhile, the mirrored array continues to provide files, but with only one drive.
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User profile for user: japamac
japamac
User level: Level 7
24,400 points

Oct 3, 2008 7:30 AM in response to motsteve

Some more interesting information is had in this article about the virtues of SoftRAID vs. OS X RAID.
I've got backup to my backup. Call me paranoid if you like, but I hate standing there looking like a horse's tail end and crying about lost data and irreplaceable applications because I didn't do some simple housekeeping.

Add me to the "tri-backup" team (the wife hates all my hard drives.... sees money spent, I guess....).
I also keep 'hard copy" DVD of archived data, and all photos and audio. It only takes losing some important data once to underscore the importance of backup. In my case, it was a near miss (was able to scavenge the SCSI drive), but it scared the bejeebers outta' me...... 🙂
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User profile for user: Grant Bennet-Alder
Grant Bennet-Alder
User level: Level 10
126,985 points

Oct 15, 2008 4:32 PM in response to rezwits

That article japamac cited says booting should also work for Raid 0 (striped), provided you are using 10.3 or later.

I wanted to add one more note for completeness. Due to protocol restrictions, two IDE/ATA drives sharing the same cable as Master and Slave get no benefit from overlapped I/O. ATA requires the first command to complete (seek, read, transfer_data) before the second command can even begin. For top performance, your mirrored or striped drives should be on separate cables, if you have the hardware to support it. But don't move one to the CD Drive cable, sharing with the CD slows it down much more, because IDE/ATA can only see speed data for the slower drive.

The Mirrored Drive Doors G4 has an ATA-100 drive cable as well as an ATA-66 drive cable, in addition to its CD-drive cable.
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Can I Boot from a RAID 1 (mirror) in my G4?

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