On Thu, 16 Nov 2017 13:34:52 -0500 Dan Norton <dnor...@mindspring.com> wrote:
> On 11/13/2017 09:52 PM, Felix Miata wrote: > > Dan Norton composed on 2017-11-13 21:38 (UTC-0500): > > > >> How do you set up LVM so that install does not clobber one of the > >> siblings? During installation, for partitioning, do you pick > >> "Manual" or "Guided -*" ? > > I don't think I've ever used Debian's, or any Debian derivative's, > > "guided". I can't remember the last time I didn't pick manual, > > after *fully* preparing in advance to my specifications. > > > > Manual will list what partitions and volumes exist, so if you've > > fully prepared logical volumes in advance, all that should need to > > be done within manual is select mount points and mount options for > > those you wish used. If volumes exist but are not formatted, then > > formatting would be a third selection using manual. > > A better description of what I want is "multiboot", instead of "dual > boot" in this thread. I can see having up to 4 systems installed, all > Debians, on one disk drive. There is an item in [1] which I see that > reads: > > 6. Disable LVM support > > which is puzzling. Can multiboot be set up within LVM on one disk > drive? Or, is it necessary to disable LVM, define multiple logical > partitions with fdisk or parted for example, install in these > partitions, and then set up LVM separately on each system? I see the date of the page is 2015, but to be honest, a lot of this page is completely obsolete, even more so if you're not using DOS, OS/2 or early Windows. I would not even swear that item 6, LVM, even refers to the Linux system. There's certainly no problem about mixing multiple booting with lvm. A volume group would normally be declared within a single old-style IBM partition, but doesn't have to be. Think of multiple hard drives, each containing multiple old-style partitions, then think of multiple lvm volume groups, each with multiple volumes, roughly overlaid on the drives and partitions but not physically matching them. A volume group can consist of multiple complete partitions on different drives, and the volumes it contains need not bear any relationship to the underlying partitions. Multiple OSes will still use one overall bootloader, which may or may not redirect to other bootloaders. It is common, therefore, to use a single physical partition for /boot, common to all *nix OSes, but by no means necessary. /boot can be an LVM volume if you wish, but a booting problem is slightly easier to deal with if the kernel and grub stuff is in a standard partition, you don't need to worry about looking up the lvm commands in addition to the grub set. My workstation, for example, has a 1GB primary partition for /boot, and the rest of the drive is a second primary partition which maps exactly to a volume group. The volume group is then divided into volumes, which mostly act like old-style partitions, at least as far as mounting goes. You can have a lot of them. I have two drives set up the same, as I migrated from one to a newer one. After adjustment, the grub installation of the new drive handles the boot, and the kernel used by the old system lives in the /boot partition of the old drive. All of this could have been integrated into one volume group, but it's two because that's how the system evolved. I could pull the old drive, which I hardly ever touch now, plonk it into another PC and boot it with minimal fiddling about. So you have a common grub, basically from the latest installation unless you tell the installer otherwise, and before the installation is finished it should have detected any other bootable OSes anywhere in the hardware. You've been advised not to share other partitions, even /home, but several /homes can live in differently-named lvm volumes in the same volume group. Or not, by your preference. You can, for the most part, treat volumes as partitions, and not worry about whether they are primary or logical. You should probably track down a few tutorials on multiboot and lvm, read through them to get a feel for what needs doing. It's always difficult reading a manual for something and working out from that what steps you need to take to do something. Things like UEFI boot and disc encryption complicate things, so probably best to avoid them on your first attempt(s) if the hardware allows. If you're starting with a bare drive and your BIOS allows old-style IBM partitioning, that's the way to go to get the hang of this. -- Joe
