USELVM - useless?

aeosynth · 2010-02-06 21:40:15

I'm using LVM, and booting fine with

USELVM="no"

in my rc.conf. Is this line useless? I do have lvm2 in the hooks part of my mkinitcpio.conf, so I'll do some tests later to see what happens without this (on a new install of course ).

sand_man · 2010-02-07 03:17:23

Well here is the relevant part of rc.sysinit.

if [ "$USELVM" = "yes" -o "$USELVM" = "YES" ]; then
        if [ -x /sbin/lvm -a -d /sys/block ]; then
                # Kernel 2.6.x, LVM2 groups
                /sbin/modprobe -q dm-mod 2>/dev/null
                stat_busy "Activating LVM2 groups"
                /sbin/lvm vgchange --ignorelockingfailure -a y >/dev/null
                if [ $? -ne 0 ]; then
                        stat_fail
                else
                        stat_done
                fi
        fi
fi

Do you do any of that manually? I think its mostly just modprobing dm-mod which udev is probably doing automatically anyway. So it's possible that USELVM is not needed.

Last edited by sand_man (2010-02-07 03:18:21)

fukawi2 · 2010-02-07 05:58:19

I noticed this recently too... I had a machine using LVM that I accidentally left set USELVM to 'no' but it still booted fine... Perhaps one of the udev or kernel upgrades or something has made USELVM redundant?

sand_man · 2010-02-07 22:10:02

fukawi2 wrote:

I noticed this recently too... I had a machine using LVM that I accidentally left set USELVM to 'no' but it still booted fine... Perhaps one of the udev or kernel upgrades or something has made USELVM redundant?

Probably but I'm guessing there must be a special case for it.

tomk · 2010-02-08 00:10:08

If lvm is in your initramfs, everything that sand_man quoted above has already happened in early userspace, before rc.sysinit is processed. Have a look at /lib/initcpio/{hooks,install}/lvm2 for details.

Bottom line - rc.conf USELVM is only relevant if you don't use lvm at boot time.

aeosynth · 2010-02-09 23:34:27

sand_man wrote:

Do you do any of that manually?

Nope.

tomk wrote:

Bottom line - rc.conf USELVM is only relevant if you don't use lvm at boot time.

How would you set up your system to not use lvm at boot time? I'm aking because the wiki says

http://wiki.archlinux.org/index.php/Official_Arch_Linux_Install_Guide#Configure_System wrote:

USELVM: Set to "yes" to run a vgchange during sysinit, thus activating any LVM groups

There should be a note saying (only relevant if you set lvm to not start at boot by doing ___).

Arch Linux

#1 2010-02-06 21:40:15

USELVM - useless?

#2 2010-02-07 03:17:23

Re: USELVM - useless?

#3 2010-02-07 05:58:19

Re: USELVM - useless?

#4 2010-02-07 22:10:02

Re: USELVM - useless?

#5 2010-02-08 00:10:08

Re: USELVM - useless?

#6 2010-02-09 23:34:27

Re: USELVM - useless?

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