My primary 2008R2 Enterprise SQL Server box is suddenly having issues. The box has been rock solid since it was first built last year, but we're suddenly having issues despite almost nothing having changed. Some Windows updates were installed last week, but we have now rolled them all back in an attempt to rectify the issue. However, it doesnt seem to have been the problem.
BACKGROUND
We are seeing some very bizarre behavior. Nothing has changed as far as data file sizes or server load, but suddenly, after over a year of flawless operation, the system is constantly choking, particularly when performing backups.
The SAN shows low/normal disk queue lengths (3-4) but Windows will show 10x that in PerfMon. SQL Server will rocket the disks to 100%, and all 10 cores on the box will hit 100% as well, even under fairly minimal loads. We'll see...