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    Hi folks,<br>
    <br>
    Whilst testing migration, I found an oddness that others might
    benefit from knowing about.<br>
    <br>
    <b>My environment:</b><br>
    Two hosts, CentOS underneath, Ovirt 3.4.1&nbsp; hosted-engine (clean
    build) on top.<br>
    <br>
    <b>What happened:</b><br>
    Doing migration testing (it is so nice to have reached this stage),
    I found that VMs could migrate from the first host to the second,
    but not the other way.<br>
    To be clear, by "first host", I mean the first one that Ovirt was
    installed on. Host ID 1.<br>
    <br>
    The Ovirt GUI's messages are uninformative (it failed; I knew that):<br>
    Migration failed due to Error: Fatal error during migration
    (VM:testvm1 , Source: host2.ovirt, Destination:host1.ovirt ).<br>
    <br>
    <b>Logs to look for:</b><br>
    vdsm log on the source host (host 2) is informative, and includes
    this clue:<br>
    <tt>libvirtError: operation failed: Failed to connect to remote
      libvirt URI qemu+tls://10.0.14.9/system</tt><br>
    <br>
    which leads us to <b>libvirtd</b>. Let's have a look at it:<br>
    <br>
    This is host 2, the one that's working, I can migrate to it:<br>
    <tt>[root@host2 ~]# grep -v ^# /etc/libvirt/libvirtd.conf | grep -v
      ^$</tt><tt><br>
    </tt><tt> listen_addr="0.0.0.0"</tt><tt><br>
    </tt><tt> unix_sock_group="qemu"</tt><tt><br>
    </tt><tt> unix_sock_rw_perms="0770"</tt><tt><br>
    </tt><tt> auth_unix_rw="sasl"</tt><tt><br>
    </tt><tt> host_uuid="a1e1b804-1b88-4380-8ccc-7802b3a025bb"</tt><tt><br>
    </tt><tt> keepalive_interval=-1</tt><tt><br>
    </tt><tt> log_outputs="1:</tt><tt><a class="moz-txt-link-freetext"
        href="file:/var/log/libvirt/libvirtd.log">file:/var/log/libvirt/libvirtd.log</a></tt><tt>"</tt><tt><br>
    </tt><tt> log_filters="3:virobject 3:virfile 2:virnetlink&nbsp;&nbsp;&nbsp;&nbsp;
      3:cgroup 3:event 3:json 1:libvirt 1:util 1:qemu"</tt><tt><br>
    </tt><tt> ca_file="/etc/pki/vdsm/certs/cacert.pem"</tt><tt><br>
    </tt><tt> cert_file="/etc/pki/vdsm/certs/vdsmcert.pem"</tt><tt><br>
    </tt><tt> key_file="/etc/pki/vdsm/keys/vdsmkey.pem"</tt><tt><br>
    </tt><tt> </tt><tt><br>
    </tt><tt> [root@host2 ~]# lsof | grep libvirtd | grep TCP</tt><tt><br>
    </tt><tt> libvirtd&nbsp; 22244&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; root&nbsp;&nbsp; 13u&nbsp;&nbsp;&nbsp;&nbsp; IPv4&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
      99175113&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 0t0&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; TCP *:16514 (LISTEN)</tt><tt><br>
    </tt><br>
    Now the one that's not working, with differences highlighted.<br>
    <br>
    [root@host1 ~]# grep -v ^# /etc/libvirt/libvirtd.conf | grep -v ^$<br>
    <b>listen_tcp = 0</b><br>
    <b>auth_tcp = "sasl"</b><br>
    <i># lines below here were added by vdsm</i><br>
    listen_addr="0.0.0.0"<br>
    unix_sock_group="qemu"<br>
    unix_sock_rw_perms="0770"<br>
    auth_unix_rw="sasl"<br>
    host_uuid="a9fd3fe1-b3a7-48f7-8870-cff3ee4c1f62"<br>
    keepalive_interval=-1<br>
    log_outputs="1:<a class="moz-txt-link-freetext"
      href="file:/var/log/libvirt/libvirtd.log">file:/var/log/libvirt/libvirtd.log</a>"<br>
    log_filters="3:virobject 3:virfile 2:virnetlink&nbsp;&nbsp;&nbsp;&nbsp; 3:cgroup 3:event
    3:json 1:libvirt 1:util 1:qemu"<br>
    <b>listen_tcp=0</b><br>
    <b>listen_tls=0</b><br>
    ca_file="/etc/pki/vdsm/certs/cacert.pem"<br>
    cert_file="/etc/pki/vdsm/certs/vdsmcert.pem"<br>
    key_file="/etc/pki/vdsm/keys/vdsmkey.pem"<br>
    <br>
    For the sake of text mail clients, the different lines were:<br>
    <b>listen_tcp = 0</b><br>
    <b>auth_tcp = "sasl"</b><br>
    <b>listen_tcp=0</b><br>
    <b>listen_tls=0</b><br>
    <br>
    and, owing to the listen_tcp=0 (yes, it appears twice in the config
    file), there was no libvirt tcp socket listening here.<br>
    <br>
    Comment out those four lines to make it the same as the working one,
    restart libvirtd, and now I can migrate both ways.<br>
    <br>
    WARNING: If you are in production already, make sure to migrate your
    VMs off host 1 BEFORE restarting libvirtd. I found that restarting
    libvirtd caused guest VMs to die, which doesn't bother me - I've no
    production VMs on there yet, though we're not far off, touch wood.<br>
    <br>
    Now, the command to restart libvirtd:<br>
    <br>
    [root@host1 ~]# initctl restart libvirtd<br>
    libvirtd start/running, process 16279<br>
    [root@host1 ~]# lsof | grep ^libvirtd | grep TCP<br>
    libvirtd&nbsp; 16279&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; root&nbsp;&nbsp; 13u&nbsp;&nbsp;&nbsp;&nbsp; IPv4&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 104492880&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
    0t0&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; TCP *:16514 (LISTEN)<br>
    <br>
    At this point, host1 becomes unresponsive in the Ovirt GUI, and when
    it comes back all by itself, we can migrate to it. In the first
    couple of minutes, you might see a reinitializing message when you
    start migration; it'll queue, and it'll work.<br>
    <br>
    End of that problem, for me at least.<br>
    <br>
    Others who've more experience than I may critique the libvirtd
    config. This is the only manual intervention I've done with it.<br>
    <br>
    For developers:<br>
    - I didn't have this problem with 3.3, but then, I didn't have
    hosted-engine then either.<br>
    - My 3.4.0 environment (my first hosted-engine) is mostly dead, so I
    can't say whether this problem was there or not.<br>
    - vdsm had configured both machines' libvirtd.conf, though slightly
    differently.<br>
    - I can see that some of the config above the vdsm section was
    slightly different; I put this down to, maybe, I would usually yum
    -y update before installing ovirt; I might have done it the other
    way around; my libvirtds are the same version now, but could have
    been different earlier.<br>
    <br>
    Here is what vdsm had added to ach libvirtd.conf<br>
    <br>
    host1:<br>
    ## beginning of configuration section by vdsm-4.13.0<br>
    listen_addr="0.0.0.0"<br>
    unix_sock_group="qemu"<br>
    unix_sock_rw_perms="0770"<br>
    auth_unix_rw="sasl"<br>
    host_uuid="a9fd3fe1-b3a7-48f7-8870-cff3ee4c1f62"<br>
    keepalive_interval=-1<br>
    log_outputs="1:<a class="moz-txt-link-freetext" href="file:/var/log/libvirt/libvirtd.log">file:/var/log/libvirt/libvirtd.log</a>"<br>
    log_filters="3:virobject 3:virfile 2:virnetlink&nbsp;&nbsp;&nbsp;&nbsp; 3:cgroup 3:event
    3:json 1:libvirt 1:util 1:qemu"<br>
    #auth_tcp="none"<br>
    #MyComment#listen_tcp=0<br>
    #MyComment#listen_tls=0<br>
    ## end of configuration section by vdsm-4.13.0<br>
    <br>
    host2:<br>
    ## beginning of configuration section by vdsm-4.13.0<br>
    listen_addr="0.0.0.0"<br>
    unix_sock_group="qemu"<br>
    unix_sock_rw_perms="0770"<br>
    auth_unix_rw="sasl"<br>
    host_uuid="a1e1b804-1b88-4380-8ccc-7802b3a025bb"<br>
    keepalive_interval=-1<br>
    log_outputs="1:<a class="moz-txt-link-freetext" href="file:/var/log/libvirt/libvirtd.log">file:/var/log/libvirt/libvirtd.log</a>"<br>
    log_filters="3:virobject 3:virfile 2:virnetlink&nbsp;&nbsp;&nbsp;&nbsp; 3:cgroup 3:event
    3:json 1:libvirt 1:util 1:qemu"<br>
    ca_file="/etc/pki/vdsm/certs/cacert.pem"<br>
    cert_file="/etc/pki/vdsm/certs/vdsmcert.pem"<br>
    key_file="/etc/pki/vdsm/keys/vdsmkey.pem"<br>
    ## end of configuration section by vdsm-4.13.0<br>
    <br>
    Hope this helps someone else.<br>
    <br>
    cheers,<br>
    <br>
    <br>
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