x86 32bit to 64bit server conversion - tips? experiences?

[MrUlterior]

The Situation
I have a AMD XP 2000 MP (single CPU, the other died .. ) server with 2GB RAM, running LVM ontop of RAID-1 with about a TB of diskspace. The server generally is used for:

• File server (Samba for win32 clients and NFS for *nix)
  
• Loop-AES encrypted user home dirs
  
• Icecast server
  
• MPD Server
  
• Redundant MySQL Server
  
• Backup server (rdiff-backup of all boxes)
  
• Vmware-Server (contains Win2003 advanced server & FreeBSD 6.0 & 5.4 for development purposes)
  

Since the 2nd CPU died, the first is pretty much taxed to its limits 24/7 (Load average 6 - 10 depending on the time of day), additionally the Tyan motherboard has run out of slots so I'm unable to add diskspace.

As an "upgrade" I'm going to replace the Athlon 2000 MP with an AMD Athlon 64 3000+ which will hopefully perform a little better, and switch the mobo to one with an additional four SATA ports allowing me to still grow without retiring working HDDS.

The Question
My question is what is the simplest most effective method to convert this system to 64bit entirely?

The Tentative Plan
The FAQ quite specifically states that "emerge -e world" will NOT work. So my intention is to build a new chroot 64bit environment on another 64bit machine. In this environment, I'll follow the standard install, emerge -e world, then emerge all the needed packages, finally replace the config files with the known working versions from the live server. Once this is done, I shall test by booting the chroot via NFS in VMWARE, which will hopefully will allow me to fix most problems before I finally copy the entire chroot onto the existing box's /

Any advice or relevant experiences? Please share! Remember the goal is to guarantee that the chroot is as close as possible to a config that will work on the server, thus incurring minimal downtime.
_________________

"Misanthropy 2.0 - why be racist in the digital age?" - Dave Bell
http://xs.mw

[juhah]

Lets hope that the raid/lvm/ext3 (or what ever file system you have) is 64bit friendly.

How I would do it:
[list=]
[*] Create backup of all valuable data
[*] Make clean install
[*] Restore backups
[/list]

Your plan of making clean install in chroot and by testing in vmware sounds good.

I would not recommend copying of chroot into server's / by overwriting existing files. Format / and /usr and others before copying of chroot. Having 32bit libs and binaries lying around doesn't sound good.

[MrUlterior]

[tkdfighter]

Well, I've done this before:

First, pretend you are installing Gentoo from scratch. Do a stage 3 install.
Then, copy over your world file, /etc and whatever else you need (/home, /root, ...).
emerge -e world
Done.

[MrUlterior]

[gian]

I had exact same problem, i.e. the "sizeof" message while emerging glibc.

I tryied

gcc-config -l

and found I was not running the latest profile. Changing to the latest installed gcc compiler solved the problem (obviously sourcing /etc/profile in the shell I was using to emerge glibc). I'm not sure the problem wa with the compiler, or, simply, the system needed those nice little operations that are prformed when you change a gcc profile.

[Corona688]

[tkdfighter]

Well, I actually wanted to copy over gcc and glibc from a stage3 at first to go from no-multilib to multilib, but I kind of messed that up, bad.

Then I thought: what's the best and quickest way to reinstall my Gentoo, without having to emerge all my programs manually and moving my data around? So I came up with this solution: install Gentoo anew and copy over my world file. Be careful to not mount /home and to backup /etc before attempting this. I did not backup /etc until it was too late, having overwritten some important files (fstab, ...).

Here's the procedure I would use if I had to do it a second time:

[juhah]

[gentuse]

[MrUlterior]