I currently have a VM running Windows Server 2012 DC, with 4GB of RAM and a dual core CPU. This machine has Active Directory running, so is also a DNS and DHCP server.

The problem I have is thus: as soon as I install Exchange 2013, the machine is all but unusable. Everything grinds to a halt and rebooting takes forever. Once back up, it's no better.

The best example of how bad it gets is that other machines can't unresolved IPs through it anymore.

Alongside this, I can't access the OWA or ECP either, though I suspect the timeouts are due to the lack of resources.

Task Manager shows almost 100% of RAM is being used, with IIS the main culprit. The CPU usage doesn't look bad until I check the host, and the VirtualBox session is using 100% of the host CPU.

My question: I don't have much experience with IIS - where should I start trying to work this out? How is it using 4GB of RAM? The VM is also hammering the HDD, presumably paging due to the lack of RAM.


  • 2
    4 gb has not been enough for those roles for several years.
    – Greg Askew
    Jan 30, 2013 at 22:43
  • I fear you're confusing storage and RAM, but point taken. Jan 30, 2013 at 22:45
  • doubtful, you can get 16GB easily enough on a laptop these days.
    – Sirex
    Jan 30, 2013 at 23:07
  • 1
    I doubt that he's confusing the two. I've got an Exchange server running just a mailbox role and using all of 24Gb RAM quite cheerfully. I'd also suggest that the Windows DC role is best left on a dedicated machine (virtual machine, at least) rather than sharing with Exchange.
    – Rob Moir
    Jan 30, 2013 at 23:20
  • Nice edit/delete there from whoever it was. RobM, someone suggested that his phone had more RAM than 4GB, hence my comment. Jan 31, 2013 at 8:13

1 Answer 1


Microsoft recommends a minimum of 8 GB of RAM for combined mailbox/CAS server. I wouldn't recommend less than that even on Exchange 2010, unless it were in a test environment (I use 4 GB for my 2010 test server).

Like SQL Server, Exchange mailbox servers will appear to use all of the RAM you give it as the Store process will reserve it for use, but if Exchange is not memory-starved, it can back off if the OS or other applications require more.

  • Thanks for the reply. I'll take another look at the specs - could I get away with less than 8GB if I used two VMs, I wonder. Jan 30, 2013 at 23:07
  • 1
    Sorry, my link might not be very visible above, but click on "Microsoft recommends," and expand the Hardware section. Memory: Varies depending on Exchange roles that are installed. Mailbox: 8 GB minimum, Client Access: 4 GB minimum, Mailbox and Client Access combined 8 GB minimum. How many mailboxes are you trying to host on this configuration? Jan 31, 2013 at 4:33
  • I've not actually set any mailboxes up yet, it was too slow to manage :) Jan 31, 2013 at 8:09
  • The reason I asked is that on top of 8 GB of RAM minimum for an all-roles server, we normally add an additional 10 MB per mailbox, so if you had a single all-roles server with 200 users, I would recommend 10 GB of RAM (8 GB + (200 * 10 MB)). Jan 31, 2013 at 14:36

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