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  • Bottleneck

    Hello,

    I am running three virtual machines in a host.

    The CPU usage percentage is 38% but the Disk usage is always 100% , and then things become really slow.

    So, even when the CPU is fast, and only uses 38% of its capacity, the disk is undermining the whole thing ?

    I attach an image. Click image for larger version

Name:	Disk at 100% but CPU at 36%.png
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Size:	6.0 KB
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    -
    Madrid (Spain).

  • #2
    Fairly normal behaviour as memory is getting maxed out so lots of swapping to disk (note the host has a reserve - see https://blogs.technet.microsoft.com/...serve-setting/)

    I assume traditional hard drives, not SSDs. Your solutions would be
    Ideal: add SSD and run your VMs from that
    Second best: add a RAID 10 or 0 array for the VMs
    Third:: Add a single physical drive for VMs to balance disk load

    Also look at the drive speed (7200RPM is considerably better than the normal 5400)
    Tom Jones
    MCT, MCSE (2000:Security & 2003), MCSA:Security & Messaging, MCDBA, MCDST, MCITP(EA, EMA, SA, EDA, ES, CS), MCTS, MCP, Sec+
    PhD, MSc, FIAP, MIITT
    IT Trainer / Consultant
    Ossian Ltd
    Scotland

    ** Remember to give credit where credit is due and leave reputation points where appropriate **

    Comment


    • #3
      Thanks Ossian.

      What do you mean "maxed out" . I did not understand that. English is not my native language, sorry about that.

      ​Yes, traditional hard drive, the host is a laptop.

      I will look up for SSD prices.

      You mean Raid 10 or 0 within the guest OS ?

      Also, when you say: "add a single physical drive for VMs to load disk load" , I assume you mean a disk for the host (the laptop) ?

      Since this is a laptop, I believe it is 5400 rpm. Can I change it to 7200 ?

      Thanks a lot !


      -
      Madrid (Spain).

      Comment


      • #4
        Sorry - "Maxed Out" means running at full capacity (or using as much as can be used). In this case the disk is "maxed out" and the memory looks as if it is too (remembering the memory reserve I linked to)

        I mean RAID on the host - not the guest. The aim is to split the activity HyperV is causing among as many disk spindles as possible

        You can change the drive to 7200 rpm (would need to image / reinstall the host OS), but if you are buying a new one, I would look at an SSD (more $$$ but MUCH better performance). You could add it as an additional drive by removing the DVD from the laptop and replacing it with a caddy to hold a standard sized drive - this should cost you around $20 / 15 on top of the cost of the SSD, which should be around 120 for about 500Gb
        Tom Jones
        MCT, MCSE (2000:Security & 2003), MCSA:Security & Messaging, MCDBA, MCDST, MCITP(EA, EMA, SA, EDA, ES, CS), MCTS, MCP, Sec+
        PhD, MSc, FIAP, MIITT
        IT Trainer / Consultant
        Ossian Ltd
        Scotland

        ** Remember to give credit where credit is due and leave reputation points where appropriate **

        Comment


        • #5
          Originally posted by loureed4 View Post
          Thanks Ossian.

          What do you mean "maxed out" . I did not understand that. English is not my native language, sorry about that.

          ​Yes, traditional hard drive, the host is a laptop.

          I will look up for SSD prices.

          You mean Raid 10 or 0 within the guest OS ?

          Also, when you say: "add a single physical drive for VMs to load disk load" , I assume you mean a disk for the host (the laptop) ?

          Since this is a laptop, I believe it is 5400 rpm. Can I change it to 7200 ?

          Thanks a lot !

          You probably shouldn't expect very good performance from a laptop running 3 virtual machines. A laptop really isn't an appropriate platform for virtualization. You kind of just need to accept that the performance is going to suffer if you're running all 3 virtual machines simultaneously. The laptop probably has a 7200 RPM SATA hard drive (slow) and is experiencing disk I/O contention between the 3 virtual machines AND the host operating system. This is something you're just going to have to accept and live with if you're going to run these 3 virtual machines simultaneously.

          Comment


          • #6
            That was really informative, thanks both !
            -
            Madrid (Spain).

            Comment


            • #7
              Joe,
              I agree with you for operational VMs, but for training / learning, a decent laptop can be fine
              I have a set of 10 laptops (i3, 16Gb RAM, HD for OS and SSD for VMs) which run most current Microsoft courses very well (up to about 6 VMs)
              Note it was the SSDs which made the difference - before that things were very slooooowwwww.

              The only limitation is whatever iD-ten-T decided that 1366x768 was a suitable screen resolution for anything except watching videos.....
              Tom Jones
              MCT, MCSE (2000:Security & 2003), MCSA:Security & Messaging, MCDBA, MCDST, MCITP(EA, EMA, SA, EDA, ES, CS), MCTS, MCP, Sec+
              PhD, MSc, FIAP, MIITT
              IT Trainer / Consultant
              Ossian Ltd
              Scotland

              ** Remember to give credit where credit is due and leave reputation points where appropriate **

              Comment


              • #8
                Why did you go for i3 and not i5 or i7 ? , does that not make much of a difference?
                ​What is " ID-ten-T " ?


                -
                Madrid (Spain).

                Comment


                • #9
                  i3 was a lot cheaper than i5 - when it is 10 laptops, that becomes significant
                  I think it would have been about US $1000 difference

                  Also demonstrates you can get good performance with low specs

                  re-write iD-ten-t with numerals id10t and then read it as "idiot"
                  Tom Jones
                  MCT, MCSE (2000:Security & 2003), MCSA:Security & Messaging, MCDBA, MCDST, MCITP(EA, EMA, SA, EDA, ES, CS), MCTS, MCP, Sec+
                  PhD, MSc, FIAP, MIITT
                  IT Trainer / Consultant
                  Ossian Ltd
                  Scotland

                  ** Remember to give credit where credit is due and leave reputation points where appropriate **

                  Comment

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