On 09.01.2014 23:54, Dennis Jacobfeuerborn wrote: > Hi, > I just installed a CentOS 6.5 System with the intention of using thinly > provisioned snapshots. I created the volume group, a thinpool and then a > logical volume. All of that works fine but when I create a snapshot > "mysnap" then the snapshot volume gets displayed in the "lvs" output > with the correct information but apparently no device nodes are created > under /dev/mapper/ or /dev/(volumge_group_name). > Any ideas what might be going on here? For the people who run into this as well: This is apparently a feature and not a bug. Thin provisioning snapshots are no longer automatically activated and a "skip activation" flag is set during creation by default. One has to add the "-K" option to "lvchange -ay <snapshot-volume>" to have lvchange ignore this flag and activate the volume for real. "-k" can be used on lvcreate to not add this flag to the volume. See man lvchange/lvcreate for more details. /etc/lvm/lvm.conf also contains a "auto_set_activation_skip" option now that controls this. Apparently this was changed in 6.5 but the changes were not mentioned in the release notes. Regards, Dennis