SUMMARY: Live Upgrade versus Boot Mirrors

From: Ben Rockwood (benr@cuddletech.com)
Date: Wed May 19 2004 - 02:14:16 EDT


Thank you to everyone who responded.

The big debate here was whether or not to abandon traditional boot
mirrors for LU lock, stock and barrel. Surprisingly to me this doesn't
have to be the case. The bulk of the shops are actually switching back
and forth between mirror and LU, by breaking the mirrors, then creating
the boot environment (lucreate) and upgrading it, then rebooting into
the new BE, and then removing the BE's and re-mirroring. Done in
conjunction with Flash Archives (flarcreate) for "holy s***!" recovery
this seems to be the best method for going about things. Only 1 person
responding said that they completely abandoned mirrors for LU because
they need to maintain an extremely vigorous patching schedual and
recovery by reboot wasn't a problem.
Several people responding also noted that they were using LU for
non-upgrade purposes, namely the ability to change the disk layout on
their root disks with minimal downtime. Only 1 respondent had actually
added disks to their systems in order to mirror and use LU at the same time.

Respondents were: (without email for spam reasons)

Charles J. Giannetto
Darren Dunham (Dr Storage)
Amber Wolfe
Sal Serafino
Les Bemont
Julie Baumler
Rossman
Michelle Scott
Jim Winkle
Jeremy Loukinas
Paul Davies

Original Post was:
>I've been dragging my heals on Live Upgrade for a long long time and I
now feel its usable in a production environment. >However, many Sun
systems only have 2 disks provisioned for root disks. Currently I'm
using 2 disks per system mirrored via >VxVM or SVM. Because I've
allocated the full capacity of the disks to root/swap/other I can't
slide LU in.
>
>So here's the question. Is anyone letting go of their root disk
mirrors and solely relying on LU to cover them>? Right now I >have to
choose, mirrors or LU, and I'm leaning towards LU. The alternative is
to try and find a place to start adding UniPak's, >which I'd prefer to
avoid. I don't think anyone would want to unmirror their disks, but
given the constraints there has got to be >at least a couple of you guys
using LU solely.
>
>Any experience/opinions are appreciated. I'll summarize.

I'm including the reply from Sal Serafino. Even though I didn't ask for
an overview of actually doing the procedure he was really nice and
summed it all up really well. Seems fitting in the archives:

Hi Ben-

Very easy, but be absolutely sure that you install the LU packages from the OS
version you are migrating to, i.e. - upgrading from 5.7 to 5.9, install:

application SUNWlur Live Upgrade 2.0 05/02 (root)
application SUNWluu Live Upgrade 2.0 05/02 (usr)

from the Solaris-9 installation CDs or DVD, and make sure you read ALL the man
pages on the LU program and all its subcomponents to understand how it works. I
did my first one of these a long time ago, and I will never do an upgrade "the
old way" again.

What you do is to split the mirrors. Once you have a mirrored partition free of
its redundant component, build a *new* mirror with the extra component and leave
it "broken" with only one slice. When you do the LU, set up the mirror device
as the filesystem for /, /var, /usr, etc... When you activate the new Boot
Environment and reboot the system, you will mount the new mirror and life goes
on under the new OS. When you're sure that everything is OK, you then undo the
old mirrors and attach the newly liberated components to the new mirrors for
this BE. Do this overnight or at a time when the system can afford to be a
little slower than normal because it has very high I/O during the sync process,
especially if you are sync'ing multiple mounts. Then, you can delete the
original mirrors because they are empty and not needed anymore.

Good luck,
-Sal
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