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Every few days we have to reboot a few servers due to high memory utilization. These servers are running in an VMWare ESXi v4.1 environment. The ESXi server is not over-committed. It still has 17G free. In the VMWare ESXi configuration for the problem servers, I've set Memory Reservations based on another posting I read, but didn't seem to help.

We have 3 Windows 2008 R2 SP1 guest VMs running on the host that exhibit the problem. These VMs are used as test environments and are similarly configured, running IIS and Sql Server. The memory allocated to each VM is 8 GB, and the Sql Server memory usage is capped at 1.5 GB.

We frequently notice that the memory consumption in all these VMs have gone up to 8 GB, making the guests slow and almost unusable due to the memory pressure. The Performance Tab in the Task Manager shows this high memory usage. However, when we look at the individual processes in the Task Manager, we do not see any process that can account for the amount of memory being used. The total memory usage shown there can perhaps account for 2 - 2.5 GB, but there is no indication of where all the remaining memory is being used for. Restarting Sql Server or IIS doesn't help. rebooting the guest is the only step that releases the memory.

We have tried the memory reservation suggestion mentioned in this post, but that didn't help : What's using all my memory?

Any advice would be appreciated.

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Dave M
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    Bit more detail please? What os are the guests? Is there a performance issue? – Zapto Apr 09 '12 at 19:43
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    which memory? guest memory or host memory? also, what applications are you running in the vms? – johnshen64 Apr 09 '12 at 19:43
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    Can you clarify what you mean by "high memory utilization"? Is the ESXi server's memory filling up? Or, is the memory available to the guest OS within the VMs filling up? What symptoms are you seeing? – Shane Madden Apr 09 '12 at 19:43
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    Are you rebooting virtual machines or the ESXi servers themselves? What is the nature of this high memory utilisation? What problems does it cause and why reboot? – ramruma Apr 09 '12 at 19:44
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    Start with troubleshooting the problem instead of rebooting the servers and/or making changes based on some post you read. What process is consuming the memory? – joeqwerty Apr 09 '12 at 19:54
  • What happens if you don't reboot the servers? Do they get slow? Do they get errors? – David Schwartz Apr 09 '12 at 23:50

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Check your resource allocation to see if there are swapping and/or ballooning. Also, do you have an equivalent physical server or nonesxi vm to run the same software stack to compare with? It may not be esxi and could just be how your application configuration is causing the excessive memory needs.

johnshen64
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  • If we don't reboot the servers, performance is severely degraded. – Dave M Apr 10 '12 at 16:55
  • The problem is with the VM Guest's performance not ESXi. We are running Windows 2008 R2 SP1 & SQL 2008. We are rebooting the VM when there is noticeable performance issues. If we don't reboot the VM, performance remains severely degraded. – Dave M Apr 10 '12 at 17:02
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    sounds like something is having memory leak in your guestOS – johnshen64 Apr 10 '12 at 17:46