VMware vSphere

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  • 1.  ESXi OS Resources Usage

    Posted Nov 19, 2013 04:28 PM

    Hello community,

    I am being asked by a client to provide the actual CPU and Memory usage of a host for the ESXi OS itself, aka what is ESXi OS using for memory and cpu.  I am trying to pull the information fromany source, either PowerCLI to the host or counters from the vCenter, personally I dont care where the data comes from.  Its not giving a good picture of exactly how much memory and cpu the host itself is using.

    Also I cant seem to get a search to reply back on how to do this .  I believe its because I cant phrase my request correct for a search engine to index.  Hopefully the Forums can help here.

    Thanks,

    Boston Tech Guy



  • 2.  RE: ESXi OS Resources Usage

    Posted Nov 19, 2013 11:52 PM

    Evening,

    Fun request... never had anyone ask for this one.. I assume they are doing some type of head to head comparison against other virtualization products and a saleman told them their product is so much better...

    Last time VMware published these numbers was 4.0 :

    http://pubs.vmware.com/vsp40_e/resmgmt/wwhelp/wwhimpl/common/html/wwhelp.htm#href=c_understanding_memory_overhead.html#1…

    In addition each vm has overhead:

    http://pubs.vmware.com/vsp40_e/resmgmt/wwhelp/wwhimpl/common/html/wwhelp.htm#href=r_overhead_memory_on_virtual_machines.…

    Best I can find.  I would be suprised if this data was exposed via rest api... but if it is then it's going to require some nice powershell.

    Hope it help

    Thanks,

    J



  • 3.  RE: ESXi OS Resources Usage

    Posted Nov 22, 2013 10:52 PM

    Ha! I wish it was.  Nope this is purely budget.  Basically this client is stacking as many VMs onto Hosts as possible and wants to know where the line in the sand is before the host no longer has any resources to perform.  Some of the performance metric for the hosts are giving back some of that info if I look at VMKernel.

    The company runs a fairly large LAMP farm.  Each ESXi host is running 512GB of memory and there are currently 15 ESXi.  Since its all Linux, the VMs take as much host memory as it can whether the VM needs it or not.  The Operations team is working on that issue so the company can cut down on requirements (and most likely put more VMs onto hosts).  I need to see what the System Reservation needs to be for the Host.  The reason for this, the client has been hit too many times killing the memory on the server so that the HOST itself doesnt have enough to run internal operations.  That second link you provided pushes in the correct direction I believe. Each Host has about 45 VMs (+/- 3 or 4).  They each run about 16GB (again +/-).  This gives me about 16GBs of overhead for the Host.  Now not all the server are taking 16GB and not all servers are running at the full amount they take (love Linux).  However the hosts internal performance for memory "Used by VMKernel" is 4.5GBs... this math appears to be right and fits for what the host is doing. Again this is quick glance and quick math.

    So, hopefully this answer better of what I am looking for.  I am trying to see what the Host is using for overhead and resources need to run "itself" AND "the VMs" that are hosted on it.  This will allow me to give a proper recommendation (not quick math) of what we should set for the Hosts "System Resource Allocation" under Configuration so the host wont loose the needed Memory to operate in time of contention.

    Thanks,

    BostonTechGuy