SymptomsA container on Parallels Virtuozzo Containers for Linux 4.7 hangs in the "stopping" state and becomes inoperable:
[root@myserver ~]# vzctl stop 1234
Stopping the Container ...
Set up iolimit: 0
Set up iopslimit: 0
Unable to stop the Container; operation timed out
Several processes on the Hardware Node are in the "D" state, waiting for the iolimit_virtinfo function:
[root@myserver~]# vzps -o veid,uid,pid,ppid,vsz,rsz,state,wchan:20,cmd axfww | awk '$7~/[D]/'
666 0 18622 3212 5924 616 D iolimit_virtinfo \_ syslogd -m 0
666 516 44670 1048383 583432 28860 D iolimit_virtinfo | | \_ /usr/sbin/httpd.itk
CauseThere were known issues when, upon container stoppage, a global sync of disk subsystems was triggered. In the case that NFS shares were present, even in another container, the operation might never complete.
ResolutionThe issue is fixed in 2.6.32-042stab059.7 and later kernels. Install all pending Parallels Virtuozzo Containers updates:
vzup2date -s -m batch install --self-update