Re: Live Upgrade for Linux

Christopher Cashell wrote:
> At Wed, 26 Mar 03, Unidentified Flying Banana Eric Rostetter, said:

>>This isn't the same as Live Upgrade.  With Live Upgrade, I can install a
>>fresh OS while the machine is running, or upgrade (e.g. From Solaris 8
>>to Solaris 9) while the system is running.  In the linux world, at least

>>I agree you can do updates (install security patches, etc) this way. >>But not a full install or major OS upgrade, AFAIK.

I've upgraded a box from 7.0 to 7.3 using RPMs. It worked fine for a home system (YMMV on a production box). I wrote a program to search find upgraded versions of installed RPMS from a file list.

> A full install would be somewhat trickier, though with a little work, it

As far as I can tell, A full install with RPMs is doable... All you have to do is rpm --root /mnt/second a_long_list_of_RPMS. You can get a list of RPMS to install using anaconda. but the only way I've used anaconda is from the boot CD, so you're on your own for doing the last bit of research on that.

I've created minimal RedHat installations on clean partitions that would *seem* to be bootable using RPMs, so you can try something like that. You'd then have to update all the pertinent configuration files.

Doing a dd or tar of appropriate partitionswould also allow you to test the results of upgrades. The one thing you would have to do is modify the /etc/fstab file on the 'test' root system before you reboot, and make sure that a reference to the appropriate kernel is in the main grub directory. having your /home directory on a mountable partition helps on this.

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In terms of making the two systems reboot-compatible, you'd also need to do things like symbolically link /var/spool from the old filesystem to the new system. If you're using RedHat, you can't do that with all of /var because /var/lib/rpm contains the list of installed RPMs (which will be different on the two systems).
what other directories you do(n't) want to transfer between installations is going to be up to you.

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