Safest way to go from x86 to x86_64

[Benny Amorsen]

Paul Johnson <paul at all-the-johnsons.co.uk> writes:

> Is there a safe way to install the x86_64 system over the 32 bit version
> and then clean off the 32 bit stuff that is no longer needed?

There is no safe way to do it, but it IS in fact possible. I have done
it twice.

It is a lot of work, and I recommend against it. However, where is the
fun in life if you do not do something impossible once in a while?

First of all you need a 64-bit kernel on there (not so difficult; you
can just do rpm -i --ignorearch ...) Then you need to create a
repository file containing the relevant 64-bit repositories in
/etc/yum.repos.d/.

It is a bit difficult getting started because yum will complain about
duplicate files when you install some x86_64 packages over i386
packages. You can get around that by letting yum fetch the files and rpm
--replacefiles.

There is a risk of overwriting something vitally important and rendering
the i386 part of your system useless before you have a viable x86_64
system. Have a rescue disk handy. Other challenges can be that you cannot
necessarily trust the RPM database to survive the architecture change.
You may have to manually remove /var/lib/rpm/__* and do a rebuilddb. Or
reinstall from backup if that fails.

You will also hit some cases where yum gives up in ways that it asks you
to report to the maintainers. I have not actually reported those to the
maintainers because I imagine that this is a highly unsupported use of
yum. You can get around the problems with rpm --replacefiles and similar
tricks.

Again, do not do this if you are not prepared to lose all your data.


/Benny