My problem is performance and I suspect an IO problem with TempDB.
I have a sharepoint 2010 installation that is running on 3 VMs; App tier + web, search, database. Database storage is being provided by a presized virtual disk that is on a SAN. The databases are being mirrored to another VM/SAN setup over a VERY FAST WAN link.
The problem is performance with the sharepoint site, but particularly one sharepoint site on the farm that is being used by a document libary product called Macroview. Heavy use is being made of metadata (6-7 columns). We are using search but I don't think that is a problem we can see heavy server load when the crawl is running but performance is always a bit poor even between crawls. There are several content DBs none more than about 10GB.
However, what is odd is the activity on tempdb. I can see from the server resource monitor that tempdb is using 3MB read and 3MB write ALL the time. I cannot explain this. There is also (sometimes) a pulsing pattern to disk activity that is around 10-15 seconds. I tried to lessen the load on tempdb by creating another datafile (even though it is a virtual disk on the same SAN, clearly going through the same physical channel, I've read it can help so thought I'd try it). Now I see 3MB read and 3MB on both data files, so it looks like we have double the activity! Under load (e.g., adding a lot of files) tempDB read/write rates can go up to 10MB per sec each.
WHAT IS GOING ON??!?! I'd appreciate any hints as to whether this is normal tempdb activity and I just need more server power/IO etc.
FYI: I'm not a sharepoint admin expert, just a dev trying to find my way.