General advice on doing an install onto an external drive?

Punchcutter · Guru Joined: 11 Feb 2007 Posts: 354

Hi.... I recently bought an SSD, and I would like to do a fresh install onto it, after which it will replace the main HDD internal to my laptop (Thinkpad X61). Ideally I would like to just hook up the SSD with an external USB enclosure, do the install while booted into my usual Gentoo system (rather than booting a separate minimal install CD image), and then do the disk swap. Oh, I should also mention that I will be doing a 64-bit (amd64) install on the SSD, whereas my current system is 32-bit x86 (mainly because I didn't realize before that my hardware supported the 64-bit system!)

Seems like this ought to be straightforward, but.... does anyone have any advice about things to be careful of? Any "gotchas" to watch out for? I'm not specifically asking for advice regarding the use of an SSD, but will be happy to receive anything along those lines as well

Thanks.

The Doctor · Moderator Joined: 27 Jul 2010 Posts: 2678

The catch 22 you where looking for: you can't do a 64 install from a 32.

I believe you can partition, untar, copy any relevant configs being mindful of arch changes, you data, your /var/lib/portage/world file, etc. You will have to chroot from a 64 kernel like the system rescue CD to complete the install. In fact, I would recommend it instead of the Gentoo minimal CD.

As long as you copy your configs and your /var/lib/portage/world portage should rebuild your install with little or no problem.
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First things first, but not necessarily in that order.

Apologies if I take a while to respond. I'm currently working on the dematerialization circuit for my blue box.

Punchcutter · Guru Joined: 11 Feb 2007 Posts: 354

NeddySeagoon · Posted: Wed Jan 06, 2016 9:32 pm Post subject:

Punchcutter,

A 32 bit kernel cannot execute 64 bit code. The other way round works if you have 32 bit support in your 64 bit kernel.

If you want to boot your SSD while its still in the USB enclosure, you will want the kernel parameter rootwait or rootdelay=<sec>
This overcomes the issue with root being mounted before USB is started.

Then you have BIOS uncertainty, about how it and the kernel enumerate drives.
That can be a whole word of pain.
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Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

szatox · Advocate Joined: 27 Aug 2013 Posts: 3131

NeddySeagoon · Posted: Fri Jan 08, 2016 10:07 pm Post subject:

szatox,

Its not grub, its the BIOS that determines the HDD order for grub.
I agree, most BIOSes report the boot drive as hd(0) to grub.
My present system doesn't nor did the one before that. Maybe I'm just unlucky.

Mounting partitions by UUID or LABEL is OK in fstab but to use either on the kernel command line requires an initrd to provide the userspace mount command.
PARTUUID just works there though.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.