Converting Existing Systems From One Distro To Another?

Sam "Criswell" Hart asks: "I have been using Red Hat on my machines since RH4.2. The reasons were largely due to bandwidth issues and the fact that I could always get the latest RH ISOs for free. However, since 6.2 I have been disappointed with RH, and 7.0 with its not-quite compatible GCC would be very bad for my free-software projects. I have been thinking of switching to Caldera or possibly to Mandrake. However, I am spoiled by the fact that I can just pop in a new RH CD and upgrade my existing system quite painlessly. Because there are so many other RPM-based Linux distros out there, and they have update options, are there any (esp. Mandrake or Caldera) which can relatively easily update systems based on other distros? For example, anyone have any success or troubles trying to upgrade a RH6.2 system with Mandrake 7.2? Is it possible, or is there something significant blocking such a thing?" While updating a system with software intended for another distribution isn't necessarily good idea, are there utilities out there that can perform the necessary operations needed to convert an existing system from one flavor of Linux to another?

free ISOs

[Jordan Block]

Most other distros should have ISOs available at their websites. It should be a relatively simple thing to grab a different distro's ISOs and install a new system.

File system thoughts

[Dr. Galazkiewicz]

What I have noticed in the past is tools like turbo [x config, mouse, network, etc] ala turbolinux, are very much different than the RH tools. But the system's text config files are very similar. However I don't have high hopes that installing over anything will save all configurations, especially if the ftpd, httpd, or even mail are not the same.

I guess the question could also be, does everyone one use the same mount points? I have toyed with the idea of mounting \home on a different disk, so in theory I could hose the root \ and try different distributions.

Don't like the new gcc?

[danpbrowning]

Then install the rpms of the compiler that you do like. Not tough. It's not as bad as when they shipped the new glibc before it was ready back in 5.0.

Wipe clean, it's not that hard to rebuild.

[Anonymous Coward]

This summer I switched from Red Hat to Debian on one box. I copied some things from /etc to my home directory, then moved /home to a seperate partition. I then wiped everything clean save my home and mounted the home partition. After that it was surprisingly painless, it was just a matter of reinstalling software.

What's wrong with RH?

[Tet]

I have been disappointed with RH, and 7.0 with its not-quite compatible GCC would be very bad for my free-software projects.

How, exactly, is it bad for your free software projects? Do you actually know what's incompatible about the gcc in RH7? Binaries compiled with RH7 won't work on earlier versions of RH -- just as RH6 binaries didn't work on RH5, and RH5 binaries didn't work on RH4. But the reverse is not true. You can run older binaries just fine on RH7. And if you want to compile stuff on RH7 that will work on older versions, just use kgcc -- it's exactly the same egcs-2.91.66 that was shipped with RH6. So what, exactly, is the problem? Or are you just listening to the ill-informed whining on slashdot?

Re:Various Distros

[Tet]

Backup /home, /usr/local, /etc, and some of the directories in /opt if necessary.

A well designed system will have /home, /usr/local and /opt on separate filesystems anyway, so it's just a matter of mounting them in the appropriate places after the upgrade. Of course, this doesn't help newbies suckered into putting everything in one big filesystem by the CorelLinux install (for example -- there are plenty of other offenders).

Various Distros

[jfunk]

I've gone through a number of distros. Here's my method for conversion:

Backup /home, /usr/local, /etc, and some of the directories in /opt if necessary. I stick to /usr/local and /opt for stuff I compile myself. I also have htdocs there.

Generate a list of installed packages. With an RPM distro this is easy: rpm -qa > rpmbackup.txt

Backup the database.

Install the new distro from scratch.

Restore from backups. I drop /home, /usr/local, and whatever I saved from /opt in place.

Copy the appropriate lines from /etc/password, /etc/shadow, and /etc/groups into the new system.

Configure any software. This often means restoring a file into /etc, sometimes it's easier to just reconfigure.

Restore the database.

Install any software the new distro didn't. I now use SuSE, so this part is fairly short, TkPGP, OSS commercial, and CivCTP. I now shudder at the thought of moving to Red Hat, or anything other than Debian, due to the amount of software I'd have to install individually...

Re:What's wrong with RH?

[jmakrel]

If he's anything like me, he doesn't know what's incompatible with RH7.0 gcc... just has heard that it is.

If he's like me, that's probably what scares him.

RedHat - Debian

[AgentX]

I once converted a running RedHat machine to Debian while logged in remotely (through ssh) and I didn't even have to reboot! What I did was to compile ssh from source so that I could log in through that (you don't want the packaged version because you are going to delete that), then I logged in and removed all the packages rpm would let me, leaving just the running base system. Next, I installed dpkg, found which files those RedHat packages contained and found the equivalant debian packages (look under the debian packages link on the debian.org page. Recently I have been thinking you might be able to just untar the base system from the baseX_X.tgz file and use that, but I haven't tried it) After I installed the appropriate debian packages I deleted the left over cruft from redhat and used dselect and apt-get to get the rest of the software I wanted, and changed all the startup stuff, and ran lilo. The next time the machine was rebooted (my buddy uses windows occasionally) it booted up just like any other debian machine, and it worked fine until then too.

It's not really that hard.

Answer: Don't do it, really

[bconway]

Seriously. Some of the RedHat-based distros are upgradeable from one to another, but don't even try it with the Debian derivatives. Your best bet is by far to back up anything you need and wipe the drive. The only success story I've ever heard of working correctly is going from a RedHat install to Mandrake, but you'd surely want to wipe the drive clean anyways to do an install on ReiserFS, which has been included in Mandrake for some time.

There are really too many problems associated with incompatible distributions to list them all here, and it would only take you an afternoon to set up a fresh install and restore your settings (I've done it 3 times in two weeks with Mandrake 7.2, which I'd highly recommend among any other, except maybe FreeBSD.) I'm also curious as to when upgrading any distribution became painless, I've had nothing but problems on any system ranging from the brute-force method to the nicest of package management. Even if you're going to use the same distribution version as previously, you're most likely to clean up a LOT of crap just by reinstalling from scratch. Go for it!!

Converted from Redhat to Mandrake about two years

[Hall]

I started out running Redhat, around v5.0. I believe I skipped 5.1, but did install 5.2. Then, I upgraded to Mandrake-Linux v?? (higher than the version of RedHat I had installed at the time). It was a smooth process. I actually think Mandrake forgot to change one of the install screens where it asks if you're installing on a clean system or upgrading. I think the upgrade question asked if you're upgrading from something like a RedHat v4.2 or higher system. At the time, Mandrake had a few versions prior to the one I was installing.

Re:Don't like the new gcc?

[danpbrowning]

Then install that too. (symlinks help). Besides, if it was so hard, then how does kgcc work simultaneously?

Re:What's wrong with RH?

[Omega996]

or stick with 6.2 - unless there's some bit of software that comes with RH7 that you must have that you can't get for an older distro...

Re:free ISOs

[anderiv]

Check out LinuxISO [linuxiso.org]. You'll find the ISO's of all the major distros there. They are good about updating also.

painless upgrade

[toast0]

(assuming you're running on a box with a decent network connection, some free hard drive, and a decent amount of ram)

apt-get update; apt-get dist-upgrade

(the reason i switched to debian from slack)

Re:Various Distros

[Ex Machina]

Actually, for a single user workstation (esp. with limited drive space) I prefer one big filesystem. For a server this makes sense though.

Re:Converted from Redhat to Mandrake about two yea

[Misagon]

I have tried to upgrade certain packages on a RH 6.1 system to Mandrake 7.1. Some packages could be upgraded, while some newer softwares could not be upgraded easily. Some times I got dependency problems down to the libc level ...