[CentOS] Anything Like Solaris' Live Upgrade?

Mon Jan 28 18:47:20 UTC 2013
m.roth at 5-cent.us <m.roth at 5-cent.us>

Tim Evans wrote:
> On 01/28/2013 01:05 PM, xrx wrote:
>> On 01/28/13 21:27, James A. Peltier wrote:
>>> | Does anyone know of any sort of Linux utility that does something
>>> | like what Solaris' Live Upgrade
>>> | (http://docs.oracle.com/cd/E19455-01/806-7933/index.html) does?
>>> Nothing really until BTRFS comes of age.  I suppose you could snapshot
>>> your LVM volumes before performing the upgrade but to my knowledge
>>> there is nothing similar to Live Upgrade for CentOS
>> It does sound like you can do the roughly the same with LVM snapshots.
>> Wheras with CentOS 6; you take a snapshot of the root partition (easy as
>> "lvcreate --snapshot --name RootSnapshot --size 2G /dev/VolGroup/Root"),
>> and then do an upgrade with a reboot. If it works; you're set, if not,
>> just revert back to the snapshot (lvconvert --merge
>> VolGroup/RootSnapshot) and reboot; you'd be back to the state before the
>> upgrade.
> Thanks. You also need to manage the grub and fstab configurations to
> allow the second boot environment to be visible, bootable, and mountable.

Actually, what we do, such as the upgrade from 5 to 6, is to create
/boot/new and /new, rsync from an updated machine, then copy over
/etc/sysconfig/network-scripts/ifcfg-eth* to the new, the /etc/ssh to the
new, /etc/fstab, and, oh, yes, /etc/grub.d/rules/70-persistant-net.rules;
then using zsh's files/modules(?) load that shell into memory, them create
/boot/old and /old, move * old, mv lost+found, and /root back, then mv
new/* ., Check /etc/grub.conf, and reboot.

If we need to go back - and we did on several, when we found out the speed
issues to NFS-mounted home directories - mv * new, mv old/* ., sync, and