We have a virtual machine running Windows Server 2008R2. When we allocate 200GB RAM it is amazingly stable and runs forever with no issues.

We upped it to 350GB and it immediately became unstable. Services would stop or become unresponsive and it blue screened after 2 days. It was running under KVM and we thought KVM was the problem. So we switched to VMware, created a new VM from OVF template but still have the exact same problem.

I've raised support with Cisco and they blamed VMWare. When I raised support with VMware they blamed MS. I'm starting to think they are correct because it was the same issue on KVM.

Does anyone know of an issue with allocating more than 200GB of ram to windows 2008R2?

BTW, it is currently running SP1 but we have some errors with installing updates so it doesn't yet have all the latest patches.

  • What edition of Windows Server 2008 R2 is this: Standard, Enterprise or Datacenter edition? – joeqwerty May 10 '16 at 23:16
  • Enterprise. #Adding some useless text here because they won't let me just write Enterprise# :-) – MikeKulls May 10 '16 at 23:25
  • I'm How much RAM is in the host? – EEAA May 11 '16 at 0:13
  • What VMware product? What version? – joeqwerty May 11 '16 at 0:24
  • 2
    There is a IO problem at >256GB (Scalability of the I/O performance decreases in Windows Server 2008 R2 if more than 256 GB of physical memory is used). A hotfix is available. – Brian May 11 '16 at 0:59

Well it looks like Brian's answer was the correct one in suggesting this hostfix. Installing this patch fixed the issue. We can't completely rule out that some other random update fixed the issue as some updates were run while ram was reduced. Although this does look like the likely candidate.


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