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  • Hyper-V host configuration Server 2012r2

    Hi all,
    I am about to configure my first Hyper-V installation for a client & as I am ordering the hardware I want to be certain about the Host disk drive configuration.
    This will be a simple installation in that there will be no "Clusters" or SAN storage. I have gone with 4 x 3 TB SAS drives in a RAID-10 configuration using an Adaptec 7805 RAID controller. This will provide a 6TB partition. Is this configuration recommended over separate RAID arrays? ie RAID1 with 2 x SSD drives for the host OS & RAID-10 with the 4 x 3TB SAS drives for the guest VM's?
    I cannot seem to find an article that stipulates the best disk configuration.
    It should be noted that eventually there will be 2 Hyper-V guests on this host & I would have thought that separate RAID arrays, for each guest would have been "over the top"
    Scott

  • #2
    Re: Hyper-V host configuration Server 2012r2

    Did your pre-sales engineering work not cover this? Pre-Sales engineers should have calculated:
    A) what level of IOPS the systems going in place require
    B) what the host may need for IOPS
    C) some sort of burstable headroom. wherther you constantly need 100 iops, or maybe you need 90 most of the time, but 120 when backups run.
    d) growth. When the client invariably decides they want a new guest, will it be able to cope?


    For instance, a DC for 20 users is going to require far less IOPS than an Exchange server for 20 users.

    since I'm sure any consultant would have done adequate pre-sales research, you should know how many IOPS your target system needs.
    So now, take your RAID array and the RAID controller and determine if it's able to provide the requisite IOPS.
    If not, start again.

    Best disk configuration depends on your IOPS needs.. as well as whether particular guests will be reading more than writing, or writing more than reading, or a "roughly equal" mix of both.

    to use my previous AD & Exchange example - AD servers don't write a great deal. (Assuming they aren't also file servers.) So they might benefit from a RAID array that's tuned toward read, rather than writing. Where as Exchange might benefit more from an "equal mix".

    you should absolutely have the Host OS and the Guest VMDKs on separate volumes.
    Last edited by tehcamel; 24th September 2014, 03:34.
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    • #3
      Re: Hyper-V host configuration Server 2012r2

      Very interesting read on your input, Tehcamel.
      I'm also curious about "IOPS". From your pass experience, what tool or what method are you using to get the IOPS report?

      Thanks,
      HN

      Originally posted by tehcamel View Post
      Did your pre-sales engineering work not cover this? Pre-Sales engineers should have calculated:
      A) what level of IOPS the systems going in place require
      B) what the host may need for IOPS
      C) some sort of burstable headroom. wherther you constantly need 100 iops, or maybe you need 90 most of the time, but 120 when backups run.
      d) growth. When the client invariably decides they want a new guest, will it be able to cope?


      For instance, a DC for 20 users is going to require far less IOPS than an Exchange server for 20 users.

      since I'm sure any consultant would have done adequate pre-sales research, you should know how many IOPS your target system needs.
      So now, take your RAID array and the RAID controller and determine if it's able to provide the requisite IOPS.
      If not, start again.

      Best disk configuration depends on your IOPS needs.. as well as whether particular guests will be reading more than writing, or writing more than reading, or a "roughly equal" mix of both.

      to use my previous AD & Exchange example - AD servers don't write a great deal. (Assuming they aren't also file servers.) So they might benefit from a RAID array that's tuned toward read, rather than writing. Where as Exchange might benefit more from an "equal mix".

      you should absolutely have the Host OS and the Guest VMDKs on separate volumes.

      Comment


      • #4
        Re: Hyper-V host configuration Server 2012r2

        There are a number of tools that will give you an idea of metrics.
        Microsoft assessment and planning toolkit
        http://www.microsoft.com/en-us/downl...s.aspx?id=7826

        Is a free MS tool that will provide you with metrics of an existing system, physical or virtual.
        Otherwise, you could use the online Hyper-V or VMware tools to try to calculate the provided IOPS.
        I tend to use this to help me do some IOPS calculations
        http://www.wmarow.com/strcalc/

        As mentioned, you will need to put some thought into the design. If you get a shared component wrong the whole solution can suffer and you will loose the position of trusted advisor.

        Ask questions, consider what's going to be in use, consider how 'responsive' you need the solution to be and what the budget needs to be to get the performance required.
        The most important thing in life is to be yourself.

        Unless you can be Batman.
        Always be Batman.

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        • #5
          Re: Hyper-V host configuration Server 2012r2

          @Humannetwork & wobble_wobble, many thanks for your input. Obviously I need to place more thought into my first Hyper-V installation than I have with recent Physical server installations.
          As wobble_wobble mentioned, it is about maintaining my relationship with this client, whom I have been performing IT duties for many years.
          I appreciate the link & will use the suggested tools on the existing system which is an SQL installation for about 25 users. I know in an ideal world SQL requires separate arrays for the OS, SQL database files, log files, temp db files & even the paging file, but the budget will dictate that this is not possible.
          Does anyone out there have an SQL installation, serving about 25 users in a Hyper-V environment which is delivering performance with less than 3 drive arrays? I am considering placing the OS on a RAID1 SSD array, but this seems OTT for a member server with Hyper-V enabled.

          Comment


          • #6
            Re: Hyper-V host configuration Server 2012r2

            Originally posted by Jazit
            Does anyone out there have an SQL installation, serving about 25 users in a Hyper-V environment which is delivering performance with less than 3 drive arrays?
            You are still thinking physical about a virtual environment. Start thinking VIRTUAL.
            1 1 was a racehorse.
            2 2 was 1 2.
            1 1 1 1 race 1 day,
            2 2 1 1 2

            Comment


            • #7
              Re: Hyper-V host configuration Server 2012r2

              Hey Biggles.
              This was point of my post & the reason that I went with one large partition. I assumed that as VM's (Hyper-V) drives are just files that reside on a partition that several physical arrays would not be required.
              Having said that all of the IO's will be mapped to the one RAID array in my case.
              S the question still remains - do I need multiple arrays for a Hyper-V host?

              Comment


              • #8
                Re: Hyper-V host configuration Server 2012r2

                Originally posted by biggles77 View Post
                You are still thinking physical about a virtual environment. Start thinking VIRTUAL.
                What biggles said. Abstract out what you want to do.

                for example. You want a SQL server that's built to recommended or best practice, DB on one volume, Log on another volume, OS on a 3rd volume, Page on a 4th volume.

                If you were building this as a physical server, you'd probably look at having 3 arrays to do so.


                To abstract this down to your virtualised layer, you potenitally need something like "raid1-OSVolumes" "raid-5-datavolumes" "raid10-log volumes" or something like that.
                Maybe you need two raid-5, maybe 2 raid10.

                Then you could create your guest:

                VMDK-C on RAID1
                VMDK-D(Database) on RAID5
                VMDK-L(Logs) on RAID5
                VMDK-S(Swap) on RAID1 (Throw it on the same array.)

                however - you still need to consider in the same way. Your physical SQL host might need 1,500 iops.

                If your Hardware layer can only just attain that, you probably need to actually increase your hardware, because if it can attain it as bare-metal performance, the VM won't actually get all of it.


                Originally posted by Jazit View Post
                @Humannetwork & wobble_wobble, many thanks for your input.
                oh, and you're welcome.
                Please do show your appreciation to those who assist you by leaving Rep Point https://www.petri.com/forums/core/im.../icon_beer.gif

                Comment


                • #9
                  Re: Hyper-V host configuration Server 2012r2

                  Moved to the Hyper-V forum.

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