On Wed, Oct 31, 2012 at 9:05 PM, Thomas Bächler <tho...@archlinux.org> wrote: > I discovered some new awesomeness in LVM2 (okay, not THAT new, but > still, so far unknown to me). > > In our lvm2 package, I enabled lvmetad - this is a metadata caching > daemon that reacts to events from udev. I completely reorganized our > systemd and mkinitcpio lvm integration: > > * lvm.service and lvm-on-crypt.service are gone. > * Once you install lvm2, lvmetad.socket and dmeventd.socket are always > active in systemd. > * If you need LVM monitoring, you need to enable lvm-monitoring.service > (recommended if you use LVM, even if you don't know if you need > monitoring). I didn't enable this by default because it would always > start lvmetad.service. > * LVM is fully hotplugged via udev. You don't need to activate anything, > LVM volumes will just work. LVM no longer requires > systemd-udev-settle.service and all the race conditions should be gone. > * LVM in mkinitcpio is also fully hotplugged, lvmwait= is now a no-op. > However, LVM in mkinitcpio now requires the udev hook. > > This requires that the use_lvmetad = 1 option is set in > /etc/lvm/lvm.conf - this is now the default, but a .pacnew must be > merged if it exists. > > You can restrict the hotplugging of the volume groups with the > auto_activation_volume_list option in lvm.conf. If you uncomment that, > only the listed volumes will be enabled. This is commented out by default. > > WARNING: If you have any incomplete or clustered volume groups, none of > this will work yet! However, I doubt any Arch user uses that. >
If you use both RAID and LVM, make sure that you use the mdadm_udev hook instead of the mdadm one. I had to do this change to make my system boot with the lvm2 package in [testing].
