[Leica] Upgrading to Snow Leopard

[henningw at archiphoto.com (Henning Wulff)]

At 9:37 AM -0700 8/27/09, George Hartzell wrote:
>Henning Wulff writes:
>  > Hi Nathan,
>  >
>  > It's a good backup of your personal data, but not a good backup for
>  > this purpose.
>  >
>  > You should have a cloned backup, [...]
>
>Henning,
>
>You've asserted that a Time Machine backup isn't a good general
>purpose backup but you've never said why.
>
>So, why isn't it a good general purpose backup?


George, it's a good backup of data and programs, but in itself it is 
not bootable, and if you have trouble with your upgrade and your 
printer starts giving you problems with the new software it's 
possibly very hard and time consuming to get that all working. If you 
have a cloned backup you can boot up _anytime_ with your old system 
and configuration, and not miss a beat. This is of course mainly of 
importance if your computer is work critical. If you can afford to be 
without a computer for a week you can do all sorts of things.

If you only have Time Machine backups, you will spend many hours 
getting back a useable computer, although it will definitely work. 
You have to format a disk, install OSX and then use the restore 
function to copy the current Time Machine info back onto that disk. 
Many many hours; depending on the size and amount of info on your 
disk it could be a day or more.

With a clone it's a matter of minutes. If you use Time Machine and 
have a fairly recent clone, it's a matter of using the cloned disk to 
start up and then (possibly) using Time Machine to bring that disk 
fully up to date. That's about as fast as it gets.

BTW, if you have your time machine on an external drive that is 
formatted with the GUID Partition Table, you can install system OSX 
on it and be able to boot from it; it doesn't interfere with Time 
Machine. But.... you can't access the information that is in the time 
machine backup when booted from that disk, just as you can't access 
the info from the finder.


>
>I can rebuild my machine from it (minus the browser cache and some
>other things that Apple considers unimportant....) from a Time Machine
>backup, using Apple tested and supported programs and interfaces.
>
>If you'd like to have an independent backup then:
>
>   - plug an extra disk into the machine, use System Preferences ->
>     Time Machine to point Time Machine at it
>   - tell Time Machine to run a backup.
>   - safely remove the drive (eject, etc...)
>   - go back to System Preferences -> Time Machine and point it at your
>     normal Time Machine backup device.
>   - get pack to work.
>
>What is wrong with using Time Machine as your backup and restore
>machinery?
>
>Do you not trust Time Machine?  If not, then why are you using it at
>all?  Is it just a belt and suspenders thing?
>
>I'm actually at least as paranoid as the next guy and have used Super
>Duper and CCC backups in the past but don't do them any longer.  I do,
>however, have multiple Time Machine backups for each computer
>(regularly scheduled ones over the network to storage on either an
>Infrant NAS or a Artigo a2000 running FreeNas and episodic ones to
>external disks).
>
>Is there something that I should be worried about?
>
>This kind of reminds me of a conversation a while back that kind of
>went "You should use RAID for your image storage because it makes it
>safer, but don't use it for your system because it can't be trusted."
>I never quite made sense of that either (yes, I use an Apple software
>mirror as my system device in my Mac Pro).
>
>Thanks,
>
>g.

-- 

    *            Henning J. Wulff
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