Tuesday, June 26, 2012

Well, it could have been much worse.

I thought I would share a hyper-v war stor.

Yesterday someone from central IT called me, as he was going to update SCVMM to 2012.  I said, sounds great!  It wasn’t.

We believed that it shouldn’t bring anything down, as SCVMM mostly just monitors, so it shouldn’t be a big deal at all.  About 3 hours later, I get a call from my DBA.  Production SQL is down, along with a host of other VMs.  The dreaded “missing config file” error.  Now, I should mention that my vms are on a 3 node Win 2k8 R2 DC cluster.  Rebooting physical machines, and moving the drives around to “working” nodes didn’t work.  I could still browse to the VHDs and the config files.  Hyper-v then reported that there was a problem with a corrupted file.

So as we sitting around, thinking about backup tapes and considering how to update our resume, I remembered that once I just had rebuilt the config file for a machine that did this in the past.  Now this current machine that was failing to start had several pass through disks, memory settings, various NIC configurations that I didn’t want to have to recreate.  I decided to look into the XML config file.  Sure enough, it ended with :
      <logical_id type="string">78F….D-4FC2-someotherGUIDdigitshereFB</logical_id>
        <limit type="integer">12288</limit>
        <reservation type="integer">12288</reservation>
        <size type="integer">12288</size>
      <count type="integer">4</count>
        <limit type="bool">True</limit>
      <limit type="integer">100000</limit>
      <limit_cpuid type="bool">False</limit_cpuid>
      <reservation type="integer">0</reservation>
      <weight type="integer">200</weight>
    <stopped_at_host_shutdown type="bool">False</stopped_at_host_shutdo

Now I am no programming wiz, but I know that you at least have to close XML tags, or computers get angry.  Some quick googlin’ turned up:

So I made a backup copy of the current broken XML doc, then properly ended the XML tags that were missing.  I then crossed some fingers, right clicked “bring online” and POOF! It worked.
My heart started beating again, and my cell phone quit vibrating.