Is your Lync/SfB starved for memory?

Let’s say it was totally underprovisioned at some point. Just bumping up the RAM won’t give you the performance you expect. Here’s why:

You deploy a Server 2012 R2 template with 2GB RAM using your favorite hypervisor and just roll with the Skype for Business or Lync deployment without even thinking about it. Or… let’s say you ask for a VM to be provisioned so you can roll out SfB, and it’s underprovisioned from the start, but changing the resources would take too long so you go ahead with the deployment anyway and just wait for resources to be added later on. No time wasted. How many times has that happened? Plenty to me…

Down the road, whether it’s a reactive need for more memory, or you just realized the VM’s were completely underprovisioned and not up to those 32GB RAM Microsoft really asks for… What then? Just bump up the RAM, right?

Not quite…

Do that, and your SQL instances RTCLOCAL and LYNCLOCAL will just daydream about those sweet 32GB you allocated… Let’s take a look at a VM with only 4GB on it:

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Pretty sad, right? at no point in time can both SQL instances consume more than 941MB. What if you add RAM you say? The Minimum and Maximum Server Memory stay the exact same!!!

If you want to go ahead and change these values, you’re open to do so, but it’s not technically supported. Don’t care? then pick values for 6%-8% of your total RAM for LYNCLOCAL, and 12%-15% for RTCLOCAL. Care? Then:

  1. Open the Deployment Wizard, Install or Update, and run Step 1 again. Go grab a coffee while RTCLOCAL gets pimped out with more RAM.
  2. Then run Step 2 again. If done with coffee, get a new one while LYNCLOCAL gets a memory makeover.

You can verify the added memory now. Big difference. But, because these instances actually run on SQL Express, they won’t be able to address more than 1GB each (or 1400MB depending on who you ask). The difference between a max 327MB and 1GB is quite substantial, so this change will still make a difference.

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7/28/2016 Edit: Looks like Tom Pacyk wrote a better post over two years ago, and also points out the SQL Express limit of 1GB per instance.

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