I currently have Lubuntu 14.04 (64-bit) installed w/LVM.

I'm trying to install another Lubuntu 14.04 (32-bit). It's an HTPC and there are some retro gaming emulators that will only run on 32-bit.

That said, I can't figure out how to set up the partition table so I can dual boot these, can anyone shed some light?

Output of lvmdiscscan:

james@james-htpc:~$ sudo lvmdiskscan
/dev/ram0              [      64.00 MiB] 
/dev/lubuntu-vg/root   [       2.72 TiB] 
/dev/ram1              [      64.00 MiB] 
/dev/sda1              [     512.00 MiB] 
/dev/lubuntu-vg/swap_1 [       3.87 GiB] 
/dev/ram2              [      64.00 MiB] 
/dev/sda2              [     244.00 MiB] 
/dev/ram3              [      64.00 MiB] 
/dev/sda3              [       2.73 TiB] LVM physical volume
/dev/ram4              [      64.00 MiB] 
/dev/ram5              [      64.00 MiB] 
/dev/ram6              [      64.00 MiB] 
/dev/ram7              [      64.00 MiB] 
/dev/ram8              [      64.00 MiB] 
/dev/ram9              [      64.00 MiB] 
/dev/ram10             [      64.00 MiB] 
/dev/ram11             [      64.00 MiB] 
/dev/ram12             [      64.00 MiB] 
/dev/ram13             [      64.00 MiB] 
/dev/ram14             [      64.00 MiB] 
/dev/ram15             [      64.00 MiB] 
1 disk
19 partitions
0 LVM physical volume whole disks
1 LVM physical volume

I understand the tools to use, i.e. booting from a live cd and using system-config-lvm, I just don't know how to set up these partitions so I can choose which distro to boot on startup.

Can anyone shed some light here?


The main point of LVM is to remove the emphasis from partitions (which are inflexible) to logical volumes (which are handled more like files; you needn't be concerned with their exact start and end points). It might be a little easier if you were to use a GUI LVM tool such as system-config-lvm, shown here:

system-config-lvm screen shot

This particular example shows that my volume group consists of two physical volumes (/dev/sda5 and /dev/sdb5), which are combined together and then split up again into nine logical volumes. The image in the center shows there's a significant amount of unused space. I can create new logical volumes at will, without resizing or moving existing logical volumes. If I were to delete one of the existing logical volumes, there would be no gap in the display; anything to the right of the deleted logical volume would be moved to the left. (On the disks, the data would not move; the LVM would just keep track of where the gaps are and create new logical volumes in the available space, no matter where it is.)

In your specific case, you should verify that you have some free space. You can use system-config-lvm (it's in the Ubuntu repositories) or the underlying text-mode tools like vgdisplay. If you don't have space in your LVM, you'll need to add disk space, delete an unwanted logical volume, or shrink one or more logical volumes. Once you've got some free space, use system-config-lvm or the text-mode lvcreate to create a new logical volume for your new installation.

The likely trouble spot is that you'll also probably need a partition (outside of the LVM) to use as /boot for the new OS, and that could get tricky if you didn't plan for this when you set up your computer. (In theory, GRUB can load kernels from within an LVM, but I've never tried this myself and I've not seen documentation on how to do it.) With any luck you'll have something big enough that you can shrink to make room. You'll need to use traditional partitioning tools, like GParted, to handle this part of the task. Alternatively, if you add a disk to make room in your volume group, you can set it up with your new /boot partition, too. (I'd create another one or two for future use while I'm at it.)

  • Rod Every one of your answers has been an eye-opener to me! Thanks again! @WoodGuyPurdue: As you're a reputation 1 user: If this answers your question, don't forget to click the grey under the abysmally small number at the left of this text, which means "yes, this answer is valid"! ;-) – Fabby Mar 15 '15 at 0:30

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