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Re: mirror drives

Subject: Re: mirror drives
From: Walter Knapp <>
Date: Sat, 20 Nov 2004 10:47:39 -0500
From: Lang Elliott <>

> 
> Thanks Bret. I'm on a Mac and I notice that some of the Maxtor features are
> for PC only. 
> 
> Right now I'm using Retrospect to back up projects on to a separate drive.
> Retrospect "packages" the data in it's own special container which cannot be
> directly accessed. Thus, to re-constitute files, one must use Retrospect
> software to rebuild a new drive. In other words, if I use Retrospect I'm
> really not creating a mirror drive that can be instantly used if my primary
> external drive fails. In fact, if my primary drive fails I would need
> another external drive on which to instruct Retrospect to rebuild the
> contents.
> 
> And all this assumes that my home drive, on which I have Retrospect software
> installed and on which the Retrospect snapshots stored, remains in good
> condition.

Lang:

I don't like something where you can only get it back with some specific 
software. I use a system where the copy is normal and can be looked 
through in the usual way.

Here's what I use, it's for mac OSX or there is a version for OS9, 
though you need only finder copy to clone a OS9 system disk:
http://www.intego.com/personalbackup/

I normally maintain two clones of my main hard disk, that's over 100,000 
files, about 32 gigs right now. Most of those files are OSX! The clones 
are full bootable copies, everything, settings and all are there as of 
the time I made the clone. I could immediately boot from and continue on 
using the clone. Personalbackup will do it all automatically, but I 
don't run it that way. Any automatic system may copy when your system is 
bad. I manually start the clone process when I know the system is fine. 
You do not have to clone to the same size disk,  and can even clone your 
entire system disk to a partition, or to several disks. Or, if you have 
a huge amount of time off onto CD, optical disks or whatever. It's a 
simple drag and drop interface, push no buttons on the drive. You can 
continue working, though it does use a lot of system resources, it keeps 
the disk busy. I prefer to set it and not do anything. Changing files in 
the middle of the clone process seems like a bad idea to me.

Even with the fast Ultra 160 SCSI drives I use the first run of a clone 
takes some time. After that it's just copying changed files, including 
changed system files. If it's been less than a month, usually the clone 
will be done in a hour or less where I'm updating a previous clone. A 
USB 1 based drive would be pretty slow. It copies file by file, 
verifying as it goes.

Personalbackup has a bunch of other copy type functions. You can set it 
to backup as little as a single file or folder. And restore them. Most 
functions will operate over a network, though I've not gotten a full 
clone from another mac to work that way, the mac security messes it up. 
Everything appears to be there, but it won't boot on either mac.

Walt




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