Rightsizing the page file for Exchange

So while I was away at a jolly last week, Microsoft slipped out some updated page file sizing recommendations. The news was broken here, by Yong Rhee:

http://blogs.technet.com/b/yongrhee/archive/2013/10/23/reading-the-modern-pagefile-sizing-on-64-bit-windows-no-it-s-not-1-5x-the-amount-of-ram.aspx

and the updated guidelines are here:

http://support.microsoft.com/?id=2860880

along with a little more detail to calculate how much you might need here:

http://support.microsoft.com/kb/889654

BUT! Before you go rushing about to check that all your stuff is correct, you need to stop. Will this make any difference for Exchange? Don’t think so. Exchange uses RAM to move i/o away from the disks by stuffing as much of the database as it can manage into cache. If you have a page file larger than your amount of RAM, you run the risk of paging stuff out to disk, and losing the i/o benefit. The chopping and changing may also cause cache deflation, which is a very bad thing (http://technet.microsoft.com/en-us/library/hh344030(v=exchg.140).aspx).

The recommendations remain the same for exchange; RAM+10MB as a max and min is the correct size for a page file. Anything else is plain wrong.

http://technet.microsoft.com/en-us/library/aa996719(v=exchg.150).aspx

for all your other boxes, I suggest you follow this new guidance (unless the application advice is otherwise), but for Exchange best stick to RAM plus 10MB.