migrating from a separate /usr [SOLVED]

[A.S. Pushkin]

I'm in a quandary. I've finally completed acquiring components for a new Linux box. The old AMD64 Athlon has served me well, but it was time for
more muscle so I'm moving to a Intel i7. I'm a bit leery of SSDs, but decided to give them a try, 2 Samsung 850 Pro SSDs for Gentoo and a Seagate Barracuda 320GB
for /home. The new motherboard supports raid, but I think I'm going to try LVM2.

There is a hitch in building the new machine. I downloaded the new media, but was quickly reminded about recent changes in Gentoo news, which will make, IMHO,
doing a from scratch install rather difficult. Too many hoops to jump through. So That sends me back to last year when I cloned my old hard drive and moved to a new
one. That was due, in part, to when Gentoo moved away to a separate /usr.

With the new machine I'm planning to clone again, but I'd like to drop the separate /usr so I can drop initramfs and switch to GPT.
Is it possible to do this? Is it possible to move to a GPT based system with LVM2?

I'm not planning to wipe a production machine and will give Clonezilla a try at this. For those, who have not used Clonezilla I can really recommend it. My experience was based around
a drive that had not been completely partitioned. I was bumping up limits and had about 70GBs I needed. I installed a brand new drive cloned it and then used Gparted to alter partitions.
Awesome work from those developers as well as SysrescCD and Gentoo, of course.

All that said, if anyone has experience relating to my questions I'd appreciate their comments. I'd love to get this quad core up and running, without too much experimenting.

BTW, my current system uses an extended partition scheme: /, /var, /tmp, /opt, /usr, /home. One different partition is I keep my source code in its own partition. IF I'm able to bring /usr
under rootfs I'll drop the distfiles partition.


Thanks in advance!

[ct85711]

well, I can say it's not hard to move away from having a separate /usr, just have that directory on the / partition and not on a separate partition. Otherwise, I believe if you want to use LVM, you are going have to use a a initramfs. Otherwise you shouldn't have any issue using LVM on a GPT disk.

For me, I've been running initramfs free for over 14 years. The big thing is, I don't get to use any of the LVM features either (haven't seen anything about LVM that I need either).

[The Doctor]

Any sane method of cloning shouldn't care. You could also use rsync or rsnapshot quite easily. I have used this method and it is exceedingly simple.

I would add one thing to your setup. A 3 - 5 TB external drive and use it for backups. I use rsnapshot for daily, weekly, and monthly snapshots and restoring form these is really easy if there is ever a need.

There is a huge but coming.

[ian.au]

As the Doctor says, the problem isn't really migrating away from the separate /usr, it's more that every package on your system is going to need to be rebuilt to a new arch amd -> intel; the graphics environment nVidia -> i9xx etc..

If it's just a desktop system an i7 will crunch a handbook install in hours as opposed to the days it would likely take on your athlon. It is quite trivial to set up a system following the handbook these days, much easier from scratch than trying to adapt across as you suggest here. The problem is evolution, I'd guess that 20% of technical knowledge is obsolete at some level at any given time, if this system is 4 years old; probably close to 80% of the way it was initially configured is technically redundant, and how it runs now may be quite inadvertantly customised by decisions long forgotten that were taken to work around one issue or another.

In your case, I'd do a fresh install of the base system from scratch and spend a day or two building it up (if it is a complex or dedicated system / environment) by slowly adapting over the configs from the older machine. I'm not sure what specific problems you are considering 'hoops to jump through' but there will be many more of them trying to migrate this system than building a fresh one. For sure there will be some reading to do if you have a heavily customised environment to worry about, but that is the cost of a heavily customised environment

You can run LVM without an initramfs, but it's not reccommended: from https://wiki.gentoo.org/wiki/LVM

[A.S. Pushkin]

Thanks for the many good responses!

Yes, I did assume that I'd have to prepare to deal with the AMD64 vs. i7-4770K.