Re: Live Upgrade for Linux
From: James F. Wilkus (tflat@astrocreep.net)
Date: 04/02/03
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Date: Tue, 1 Apr 2003 21:33:57 -0500 From: "James F. Wilkus" <tflat@astrocreep.net> To: Kelly Sauke <ksauke@fastenal.com>
On 03/25 14:20, Kelly Sauke wrote:
> Maybe I need a little clarification of what Live Upgrade does. I've
> gotten a lot of response of what I would call installer utilities
> but not a Live Upgrade (if I'm wrong please point it out to
> me). What Live Upgrade does under solaris is it creates a complete
> alternate boot environment with a root /usr /var and any other
> filesystem you want. Then you can apply patches etc to this other
> boot environment and boot off of that. If there is something in the
> patch that doesn't work or screws up the machine, then you just
> reboot off the original boot environment and you're back to where
> you were before upgrading and still have access to the patched boot
> environment to fix it. Its great for upgrading production type
> servers because the 'back out plan' if you will is nothing more than
> reboot off the old boot environment. In other words you have 2 /
> filesystems, 2 /usr's, 2 /var's as well as 2 kernels. Its a
> complete boot environment copy that you can do anything to and then
> just reboot off the new environment without having to touch the
> 'live' environment.
I think most of the people that have responded to this thread have
missed the point. Yea, rpm, apt, portage, blah, blah are good
package management utilities, but we are talking apples and oranges
(or chalk and cheese :) ). LIve Upgrade gives you a backout plan,
which rpm, apt, et al, do not. Sun did not release LU to replace
the pkg* commands.
apt, for instance, does not allow you to downgrade. I tried this in
the past, and found that it wont work, please correct me if I am
wrong.
What happens after you run apt-get distupgrade and everything is
hosed? Recover from backups of course, but this can be time
consuming, especially if you need to reinstall the OS beforehand.
I have used SystemImager [1] and I think this would give you more
Live Upgrade type utility. You would be able to create your
updated OS on a separate machine, then create an image. You can
have multiple images, so you could easily revert back, voila
instant backout plan. Granted, this will not give you parallel
installations on the machine, but this, IMHO, gives you the ability
to revert the known good state as fast as you can reimage the
system.
-James
Relavent links:
[1] http://www.systemimager.org/
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- Previous message: SB CH: "after ptrace patch."
- Maybe in reply to: J C Lawrence: "Re: Live Upgrade for Linux"
- Next in thread: Noah K Sematimba: "Re: Live Upgrade for Linux"
- Reply: Noah K Sematimba: "Re: Live Upgrade for Linux"
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