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Title: PhysicalDisk counter values don't make any sense (MAP 4.0) RRS feed

  • Question

  • Software Environment
    ====================
    MAP toolkit v4.0
    Running on Windows XP SP3 x86 Spanish language (but with english locale).
    Inventory: 4 Windows 2000 SP4 and 1 Windows 2003 SP2 Servers (5 total)

    Business Case
    =============
    Main input for a SQL Server 2008 migration and consolidation project. Customer needs a proposal for migrating and consolidating ~20-30 servers running SQL 2000 and SQL 2005. Most of them run on Windows 2000 SP4 Operating Systems.

    Problem
    =======
    PhysicalDisk counters (LogicalDisk counter not present in Windows 2000) don't make sense.
    For e.g: % Disk Usage shows values lower than 2 or 3 and % Disk Idle also shows low values or zero, when instead it should be showing the opposite of the first value.
    Even though LogicalDisk counter is not present, PhysicalDisk shows the correct values when querying with performance monitor.

    1) Why is this happening?
    2) Can it be workarounded by manually inserting good values based on a .blg capture?

    NOTE: This does not happen for the Windows 2003 SP2 server.

    Tuesday, July 27, 2010 2:23 AM

All replies

  • Is the customer planning to

    1. Use the Server Consolidation wizard to try and get a proposed consolidation of the servers under Hyper-V?
      --OR--
    2. Is this a more manual process where you or the customer will use the performance metrics report to determine which servers could be consolidated together?

    If the answer to 1 is yes, then the Server Consolidation wizard does not use the PhysicalDisk counters, instead it uses the LogicalDisk counters which (as you pointed out) won't be available for the Windows 2000 machines anyway.  I believe the utilization in that case will be treated as 0 for disk IOPS and disk size which will effectively ignore these dimensions when making consolidation suggestions.

    If the answer to 2 is yes, then if you believe that the "% Disk Usage" numbers are correct you could compute the "% Disk Idle" numbers from that as a workaround.

    With respect to your specific quesitons:

    1. Why is this happening?
      I don't have a ready answer here, but I do have one follow-up question: When you query the Windows 2000 machines with Performance Monitor, are you running Performance Monitor on the XP SP3 machine on which MAP 4.0 is installed or on the Windows 2000 machine itself?  If you haven't tried running Performance Monitor on the XP SP3 machine and accessing the Windows 2000 PhysicalDisk counters remotely, it would be worth trying that to verify that there is not a problem with remote access of these performance counters from the Windows 2000 machines in general.  If there is then you might be able to find something on the web talking about this problem in general with a possible workaround.
    2. Can it be workarounded by manually inserting good values based on a .blg capture?
      Technically, yes, this is possible, but it would be a lot of work.
    Wednesday, August 4, 2010 7:05 PM
  • Customer is planning to consolidate on a physical server and on as few instances as possible. He is not interested in Virtualization because he also wants to lower Management costs (e.g also lower the number of instances to manage).

    Regarding LogicalDisk, that's correct. I tried enabling them from a Windows 2000 Virtual Machine as a test, and everything worked.

    The problem with customer is that he also had DCOM dynamic ports disabled. BTW, you should include that as a requirement in the documentation. It's not enough to enable port 135, 445, 130, etc. for RPC and DCOM to work. You also need to go to Component Services, enable DCOM (yes, in this case customer had it disabled) on default properties and probably specify a port range (because no firewall admin in his right mind will freely allow any port above 1024).

    This also requires a reboot, which customer could not do in the short term (~30 servers, it takes at least 1 month to complete rebooting on all of them given current SLAs)... all of this only to find out that for Windows 2000 servers LogicalDisk counters were also needed ... so another reboot... sigh!!

    I mean, don't get me wrong. The tool works great, but I think the documentation is incomplete with regards to requirements. For intance, it's 100 times more important IOPS numbers than CPU usage for server consolidation efforts, simply because disk performance is what usually makes the difference between one system and the other, so bottom line I think we should stress the fact that for Windows 2000 Servers logicaldisk counters MUST be enabled if customer wants accurate information for consolidation. BTW, here's a quote and link about performance impact of enabling the counters:

     http://www.oreillynet.com/pub/a/network/2002/01/18/diskperf.html?page=2

    "..The diskperf measurement layer does add some code to the I/O Manager stack, so there is added latency associated with each I/O request that accesses a Physical Disk when measurement is turned on. However, the overhead of running the diskperf measurement layer, even twice, on Windows 2000 machines, is trivial. In a benchmark environment where a 550MHz, four-way Windows 2000 Server was handling 40,000 I/Os per second, enabling the diskperf measurements reduced its I/O capacity by about 5 percent to 38,000 I/Os per second. In that environment, we estimated that the diskperf measurement layer added about 3 to 4 microseconds to the I/O Manager path length for each I/O operation. (On a faster processor, the delay is proportionally less.) For a disk I/O request that you would normally expect to require a minimum of 3 to 5 milliseconds, this additional latency is hardly noticeable..."

    Friday, August 6, 2010 3:31 PM