Arch Linux

Description:
I had originally sent this to the lvm2 mailing list, it was suggested that it might be a systemd config issue in arch, or perhaps an issue with systemd-udev.

Creating a snapshot throws an error "Attempted to decrement suspended device counter below zero." but succeeds (later discovered that this is not a consistent error). Removing the snapshot fails, attempting a 2nd time succeeds. Somewhere in this process the original LV gets locked and the system needs to be restarted to unlock it. As explained below this happens intermittently but regularly.

Here's the systemd-udev possibility, I've asked for clarification as to the change: "At certain moment systemd added a new 'feature' about locking devices while
updating internal udev state - this locking ignores any udev rule flags and opens internal lvm2 devices - so while for now it's been again disabled for 'dm' devices - you might have installed version of system which has the 'lock everything' feature in?"


log file: http://www.enlj.com/lvm.txt
lvm config: http://www.enlj.com/lvmconfig.txt

Arch Linux, lvm2 2.02.106-2

line 1: lvcreate -L1G -s -n srvrootsnap /dev/ssd.vg/server-root
Attempted to decrement suspended device counter below zero.
Logical volume "srvrootsnap" created
line 148+: why? globalfilter = [ "a|/dev/md|", "r|.*|" ]
line 921: after this point I do udevadm settle
no output from udevadm settle
line 923: lvremove -f /dev/ssd.vg/srvrootsnap - fails
Unable to deactivate open ssd.vg-srvrootsnap-cow (253:3)
Failed to activate srvrootsnap.
Releasing activation in critical section.
libdevmapper exiting with 1 device(s) still suspended.
line 1567: lvremove -f /dev/ssd.vg/srvrootsnap - again, works this time
Logical volume "srvrootsnap" successfully removed

However, /dev/ssd.vg/server-root is locked up, the VM seizes as no data
can be written to the volume. I have to restart the entire system to
unlock the volume.

This doesn't happen all the time. It happens every time I do a backup.
1 of the 7 LV snapshots created for the job, not always the same one.

hardware: Supermicro X9DR3-F,
onboard SATA controller:
00:1f.2 SATA controller: Intel Corporation C600/X79 series chipset 6-Port SATA AHCI Controller (rev 06)
/dev/md0 consists of 2 Seagate 600 240GB SSDs on that controller
/dev/ssd.vg consists of /dev/md0