I started analyzing our SQL Server PerfMon logs in Excel, and discovered this.
Red - SQL Server - Target Server Memory
Green - SQL Server - Total Server Memory
Blue - Available System Memory
Has anyone else seen this before, and should we be worried?
Configuration is identical across all servers, except for the maximum memory setting -- 14GB on Servers 1 and 2, and 10GB on Server 3. Minimum memory is zero on all servers. These are SQL Server 2008 R2 instances, each in it's own VM running Windows Server 2008 R2 (SP1 applied mid-month) under Hyper-V.
What I would expect is to see a graph like Server 1 (horizontal red line), but for Servers 2 and 3, how is the value being reported for Target Server Memory fluctuating over time? What can't be seen from the graphs I've shown is that the fluctuations match up somewhat to the Available Memory metric. Also, the server restarts (blue vertical lines) don't seem to affect the values either. Is this a bug in PerfMon?
PerfMon is set up such that all 3 servers are inside a single data collector set, with each server having its own performance counter with all the parameters we're tracking.
Any help or insight would be appreciated.