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"The virtual machine is starting" - Is DPM/SQL consuming standby memory? RRS feed

  • Question

  • When our DPM/Hyper-V servers boot, all the VMs seem to start pretty quickly. When doing maintenance however, when we have to shut a VM down, then start it or another a little while later, sometimes the VM just hangs. This has of course been reported by many people.

    I am wondering, if the memory caching algorithms with DPM, SQL, and Hyper-V are a little wonky and not working as one would expect. I would expect that if I started a VM, any Standby memory would be flushed immediately so that the VM would be granted the memory it needed and start right at that moment. If NUMA spanning is disabled, VMs would be shifted around between NUMA nodes.

    What might be happening instead, is that some processes are grabbing memory and not letting go. This is really inappropriate. In my early testing, I could run run DPM on the server with less than 8GB left for the host machine. There is no need for anything to grab 32 GB of memory. A Hyper-V machine should be able to reserve memory for Hyper-V and that's that.

    What looks like happened in this example, is that I recovered some files off of tape and Standby memory got used. 

    I restarted DPM and SQL and my VM started up right away.

    Server is 2008 R2 Enterprise with current updates, 48GB of memory, a standard DPM install (3.0.7707.0), plus Symantec 12.1. That's about it.

    I had a 4GB VM running at the point the picture were taken and a 10GB VM was finally starting. Paging file is 8192 MB.

    I have no problem increasing the paging file if need be but I really don't want to even use as much as I am. I would prefer that SQL and DPM just flow controlled in a well behaved manner and used a finite amount of memory. Otherwise, if processes start paging gobs of memory to disk, shutdowns, and everything else will take too long.

    Does anyone have any tips to restrict or control DPM / SQL memory utilization? Or is this a design problem to be fixed in an update?

    Thanks,
    Bob.

     

     

     

    Sunday, December 4, 2011 1:44 AM