Re: Converting the Mac's System Drive into a RAID (OSX 10.4.10)
- From: dg <david.goodnow@xxxxxxxxx>
- Date: Thu, 08 Nov 2007 11:33:33 -0800
On Nov 7, 3:22 pm, "George K." <mrdel...@xxxxxxxxx> wrote:
I managed to replace my dual G5's System drive with a mirrored RAID of
higher capacity. It took 96 hours, and three different FireWire
external HDs, until I found one that would boot the Mac with the
original system HD removed.
The approach taken: I cloned my System HD to an exteral FireWire HD
with Carbon Copy Cloner. I removed the System HD and tested whether
the external cloned drive will indeed boot the Mac. After finding one
that did, I installed two new, empty 400 Gig SATA drives into the
Mac's case, I set them up as a mirrored RAID with Disk Utility and
cloned the contents of the System HD back to this RAID from the
external FireWire drive.
The results are not encouraging. My original system drive was 160
Gigs, and it had 80 Gigs of files. After cloning these 80 Gigs back to
the RAID, now Get Info says my 400 Gigs RAID has 300 Gigs of files.
And all my preferences, passwords, Net bookmarks, Apple Loops and such
things vanished. (It's all retrievable, I still have the original,
removed OS drive, but still... sheesh.) When I try to see what these
supposed 300 Gigs of files consist of by double-clicking the RAID, the
folders in its window sum up to only 27 Gigs total. There's nothing
else on the desktop and there are no other users on this system whose
files could be hidden to me.
Anyone has a hunch what's going on here? The result makes me suspect
if the RAID function of OSX supports only 24-bit addressing (<120 Gig
HDs) for the System drive, or some similar defect.
Maybe I should give up on the RAID idea, and just use a file
synchronizing utility? I only wanted the RAID to have a second HD
ready in case my OS drive crashes. But a syncronizing program wouldn't
copy hidden system files, would it. Or if it would, since the two HDs
would have separate names, those system files still may or may not
work. What's the solution?
Keep in mind that many, if not most, of the problems that would cause
your system drive to crash [ex., drive firmware errors, drive
controller hardware or firmware errors, poorly implemented system or
program write errors] will induce errors which will simply be
replicated to the system's mirror drive. A mirror produces a mirror-
image, after all. Worse, [to cite a specific example] system errors
during replication of the data can induce data errors in the metadata
fork, thus the RAID 1 array actually has a higher probability of
creating problems with things like permissions. This is one reason
software-based RAID, while nifty in theory, has not put the hardware
card makers out of business. Data integrity on the hard disk is
important and can quickly become difficult to repair in UNIX-based
operating systems and Journalized file systems and Apple file system
structures, all of which conditions apply to OS 10.4 by default.
But speaking of permissions, you did scan for permissions errors /
violations, didn't you?
.
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