Windows Server 2008R2 Metafile cache behaviour

Question

We have a Windows Server 2008R2 server with 32GB of RAM, and ~1,000,000 file system objects across 15Tb of storage. The utilization is very low (only supporting 2 developers) so keeping the file contents cached (Mapped File) is not at all important, but quick access to file metadata (Metafile) IS important. The server behaviour seems to be the exact opposite. Mapped File allocation expands to use all available memory, while the Metafile appears to be frequently purged.

Example - After querying properties (Select root folders -> Properties) the Metafile allocation raises to ~750Mb (great!). However, when I do the same an hour or two later, the metadata allocation has fallen to ~300MB and a full disk rescan occurs (1-2 minutes, not great!).

How do I keep the Metafile contents cached?

RamMap output graphic is here - https://i.stack.imgur.com/1GBZ5.jpg

Answer 1

You could try increasing the minimum system file cache size with a modification to my powershell script here on server fault by inserting a line just before

$status = [MyTools.cache]::Set( $SFCMin, $NewMax, $SFCFlags ) # calls the c# routine that makes the kernel API call

and change the set line to not reduce the maximum, so it reads

$SFCMin = 1 * $GiB
$status = [MyTools.cache]::Set( $SFCMin, $SFCMax, $SFCFlags ) # calls the c# routine that makes the kernel API call

to set the minimum cache where the metafile data is stored to be 1 GiB.

Note that someone else has found that the minimum needs to be at least 64 KiB smaller than the maximum. The default maximum is 1 TiB.

You really should also look into what is causing about 21GB of "Driver Locked" active memory.