Installing a secondary gentoo

fernandoc1 · n00b Joined: 03 Jan 2010 Posts: 69

I have installed gentoo in my serial ata hard disk with KDE and the system is fully stable, with the stable packages.
But I want to try the instable packages on my ide hard disk without doing any change to my system, even to my boot loader.
My BIOS is capable of selecting the hard disk that will boot first, and I will use this feature to choose which installation I gonna use.
My question is, how can I install the unstable branch in my ide hd from inside my current gentoo installation without making any change to it?

h2sammo · Veteran Joined: 11 Mar 2009 Posts: 1025 Location: Michigan

i would think you would install gentoo on the second HDD as you did on the 1st but with the ~x86 (or amd, etc) selected in make.conf so as to try the latest unstable versions for all programs.
you would then select the HDD at boot from BIOS.

Ahenobarbi · Posted: Thu Feb 11, 2010 6:22 pm Post subject:

Boot your stable Gentoo. Partition your second disk. Make filesystems on partitions. Make dir /mnt/gentoo. Mount partition you want to use for unstable root in /mng/gentoo and follow handbook ( just don't install boot manager, make a new entry in the existing config).

NathanZachary · Moderator Joined: 30 Jan 2007 Posts: 2605

Since you already have a working Gentoo system, you can boot it up, open a terminal emulator, and perform the installation on your secondary HDD. Basically, you just follow the handbook as if you are performing a brand new installation. If you have any specific questions along the way, please feel free to post them here.
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b0nafide · Apprentice Joined: 17 Feb 2008 Posts: 171 Location: ~/

Also, why not use grub to switch between installations instead of entering BIOS to change the boot order?

fernandoc1 · n00b Joined: 03 Jan 2010 Posts: 69

Because I wanna try grub2 with some video improvements and I fear it can cause damage to my current grub installation.
I decided doing this because I was tired to have to reinstall my whole system every week after trying an disastrous "emerge -av --update --deep world".
So as I have multiple cores on my pc I would like to keep my work while my new installation is being done on another disk.
Any suggestions?

whiteghost · Guru Joined: 26 Jul 2009 Posts: 374 Location: north dakota

if booting from another drive in bios -
linux is going to see that drive as sdb
say your stable gentoo disk is sda, you would need to make configuration files- [fstab] on unstable disk /dev/sdb and grub root hd1,0

and i do not know why but when i install grub it writes to every hdd even though i use grub-install /dev/sda. i unplug other drives now before running grub.
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fernandoc1 · n00b Joined: 03 Jan 2010 Posts: 69

Good to know about this issue.
To solve this I will try to mount my disk in a Virtual Machine to make sure that no damage will be caused to my current installation of grub.
And I have a doubt: If I install grub in a virtual machine inside my real disk, I will work with my ide hdd as /dev/sda, but when back in a real machine, this will be treated as /dev/sdb. How can I solve this issue with grub?
I'm afraid that this may cause some confusion to the boot loader since grub understands disks as hd0 hd1 and it simple doesn't enable us to see how it will be in reality.

Ahenobarbi · Posted: Fri Feb 12, 2010 3:25 pm Post subject:

fernandoc1 · n00b Joined: 03 Jan 2010 Posts: 69

Ok guys.
This should be a great option that I will consider later.
But for now I can tell you that my motherboard is great and is really simple to switch between boot devices with a single press on F12 during the boot.
If this installation that I'm trying to do gets the results that I want, I will erase my current stable installation and copy the new installation to my sata disk.
So I really need my installation to be independent from each other.
They should work like they were alone on the system.
Any suggestions?

cwr · Veteran Joined: 17 Dec 2005 Posts: 1969

Well, I do this a lot (I currently have three Gentoo builds on my desktop) and
it really is easiest just to install Gentoo to another partition. Just don't re-install
(or in fact emerge) grub. Simply edit the original grub.conf file to boot the second
installation, and to be quite certain don't add the /boot partition to the second
installations /etc/fstab. That way the second installation won't know the first
one exists, and if it writes to /boot at all it will be the /boot on its own filesystem.

This is a lot simpler if you have a separate /boot partition, 128 Mb or so, but
it works even without one. If you want to use two separate versions of grub,
either use the chainloader trick described above, or install the new grub on
the old system as an initial test.

BTW, grub2 is a royal pain and largely undocumented - its documents, such as
they are, refer mostly to the very different grub1. Avoid it if possible.

Will