Is it possible to upgrade Linux Mint to 64-bit remotely?

Question

I have Linux Mint 32-bit installed on a remote server. I was wondering if I can do the upgrade to 64-bit. I have access to SSH.

Answer 1

Recent versions of Debian (wheezy, currently testing) and Ubuntu (natty = 11.04) have some limited multiarch support: you can have amd64 and i386 packages installed on the same system. I don't know if Mint follows suit. But even on a the current Ubuntu (oneiric = 11.10) you can't have executables from both at the same time, only libraries and development packages. A cross-upgrade would be difficult if not impossible; I do not recommend attempting one if you can't easily access the machine's console.

I recommend a different approach:

1. Install a 64-bit kernel for your 32-bit system. Reboot on this kernel.
2. Create a separate partition to serve as the root partition of the 64-bit installation.
3. Install a 64-bit system on that partition with debootstrap. This guide might help.
4. Carefully configure Grub on the 64-bit system so that it will boot the 64-bit system. Install that Grub on the boot sector.
5. Reboot to the 64-bit installation.

Even then step 4 is risky; if all you need is to run a few specific 64-bit programs, stop at step 3. Or even at step 1 if Mint's multiarch support is sufficient for your needs (you need a 64-bit kernel to run any 64-bit program).

Answer 2

This is hard to do even with the box in front of you. Upgrading from 32bit to 64bit is difficult because there isn't any transition state that can work. It is an all or nothing affair.

So you are talking about a re-install. You may still be able to do this remotely however, in parallel with your existing installation. Without more detail about the current setup, you could do something like:

1. Create new partitions for the new OS
2. Install virtualbox, allocating the new partitions as its disks (allocate a temporary /home partition, but afterwards you can reuse the current one)
3. Boot the virtualbox VM with the 64bit mint CD and install to the partitions
4. Copy over relevant /etc files and get the vm working as you need to
5. Once you have the VM ready enough to boot for real, copy the vmlinuz and initrd from the VM boot partition to the real boot partition. Modify the real boot.cfg / menu.lst so that it uses this initrd and kernel, and the kernel root parameter needs to point to the real partition that the new OS is installed in
6. Modify the fstab of the new OS so that it points to the real partition locations rather than the virtual ones
7. Reboot, select the new OS and cross your fingers

This sequence will likely need to be adapted for your setup.