Article ID: 126052, created on Jun 30, 2015, last review on Jun 30, 2015

  • Applies to:
  • Virtuozzo 6.0


  • It takes several minutes to list all virtual environments using prlctl:

    [root@pcs1 ~]# time prlctl list -a
    real    7m50.871s
    user    0m1.377s
    sys     0m0.028s
  • The following messages can be found in /var/log/parallels.log:

    F /IOCommunication:393832:367005/ IO server ctx [read thr] (handle 187, sender 2): WARNING: callback took too much time: about 11923 msecs. This is absolutely incorrect! Callback must be rewritten!
  • There's an NFS share with virtual machines templates, mounted on the server, and it is slow in response:

    [root@pcs1 ~]# time df -h /vz/vmtemplates
    Filesystem            Size  Used Avail Use% Mounted on
                          2.0T  1.6T  345G  83% /vz/vmtemplates
    real    0m39.074s
    user    0m0.001s
    sys     0m0.001s


prlctl queries the location of both virtual machines and templates, when it generates the list of virtual environments, so slow response from the NFS server leads to the delay in this procedure.


Fix the slowness of the NFS server.

Search Words

slow prlctl

callback took too much time

slow NFS

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