Debian
lvm2 package

  1. Bug #1657646
  2. Comment #21

Comment 21 for bug 1657646

Revision history for this message
Simon Clift (ssclift-gmail) wrote : Re: Missing thin-provisioning-tools prevents VG with thin pool LV from being (de)activated, but not its creation

This is related to a problem I've encountered today with lvmcache partitions.

From a fresh Ubuntu 18.04 install, with lvm2 installed, I create an LVM on HDD's with an SSD partitioned to provide cache:

lvcreate -n home_lv_root -L 1.2Tb vg0
vgextend vg0 /dev/nvme0n1p6
lvcreate -n home_lv_cache -L 17G vg0 /dev/nvme0n1p6
lvcreate -n home_lv_cachemeta -L 1.6G vg0 /dev/nvme0n1p6
lvconvert --type cache-pool --poolmetadata vg0/home_lv_cachemeta \
                                           vg0/home_lv_cache
lvconvert --type cache --cachepool vg0/home_lv_cache vg0/home_lv_root

then reboot. The volume vg0/home_lv_root disappears.

I try to find it:

pvscan
vgscan
lvscan
vgchange -ay

The vgchange complains it cannot complete "cache_check".

Here lies the problem: /usr/sbin/cache_check is in thin-provisioning-tools

So without thin-provisioning-tools it is possible to create an LVM2 volume which disappears on reboot.

This suggests that thin-provisioning-tools must be a prerequisite, or that cache_check be moved into package lvm2.

This also appears to be related to bug #1423796, if an LVM volume has a cache attached and is required at boot time, boot will fail completely. Creating a cached root volume seemed like a sensible thing to do. This also occurred to me today on a server config, and I moved the OS entirely onto an SSD partition rather than deal with it.