[linux-lvm] question about install on a new disk

[David Robinson]

François Patte wrote:
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> Bonjour,
> 
> I have presently an install of fedora 6 on a disk sdb with partitions:
> 
> sdb1 / (ext3)
> sdb2 LVM with lv: /usr, /var, /opt, /tmp, /home
> 
> I would like to perform a new install on sda with partitions:
> 
> sda1 / (ext3)
> sda2 LVM with same lv except /home
> 
> 
> How can I mount the "old" logical volumes located on sdb when the new
> system will be running on sda?

You just need to make sure that you use a different Volume Group name 
for the new installation. If both installations have the same Volume 
Group name you'll run into difficulties. Its easiest to avoid duplicate 
names at install time.

> As devices /dev/mapper/VolGroup00-LogVol00 etc. are created at boot time
> in the /dev of the running system I will be unable to access the logical
> volumes located on sdb....

You will be able to access them if you use a different volume group 
name. For example, if you use the volume group name "vg0" on the new 
installation, and "VolGroup00" on the old installation:

old# mount | grep mapper
/dev/mapper/VolGroup00-root on / type ext3 (rw)
/dev/mapper/VolGroup00-usr on /usr type ext3 (rw)
/dev/mapper/VolGroup00-var on /var type ext3 (rw)
/dev/mapper/VolGroup00-opt on /opt type ext3 (rw)
/dev/mapper/VolGroup00-tmp on /tmp type ext3 (rw)
/dev/mapper/VolGroup00-home on /home type ext3 (rw)


new# mount | grep mapper
/dev/mapper/vg0-root on / type ext3 (rw)
/dev/mapper/vg0-usr on /usr type ext3 (rw)
/dev/mapper/vg0-var on /var type ext3 (rw)
/dev/mapper/vg0-opt on /opt type ext3 (rw)
/dev/mapper/vg0-tmp on /tmp type ext3 (rw)

Now assuming you want to mount the /home filesystem from the old 
installation:

new# mount /dev/VolGroup00/home /home
new# mount | grep home
/dev/mapper/VolGroup00-home on /home type ext3 (rw)

You could even use the one volume group for all the logical volumes, but 
that's a bit trickier still.

--Dave