Question: Hi I have a Windows 2008 Server that is part of a two node cluster. The shared storage is on the SAN. There are 5 LUN's for this server, each 100GB large. Sometimes, during periods of high usage, the server can be slow. I can see there being high Disk writes/reads during this time, higher than other times. Some questions I hope someone can help me with 1. What Perfmon counters can I use to find out if the disks are the bottleneck 2. I have heard that the number of spindles (i.e. hard disks) can affect the speed of the application, esp if it can be read/write intensive, is this true? How can I find out if the lack of spindles is the answer? 3. If we did need more spindles, does this mean we have to increase the size of the LUN's?

Try these: Avg. Disk sec/Read (100ms or less) Avg. Disk sec/Write (100ms or less) Disk Reads/sec (baseline numbers for user activity) Disk Writes/sec (baseline numbers for user activity) Also, where are you looking to confirm the slowness? An application? File Copy? Etc. What makes you think disks are the bottleneck? Have you rules out the application? The connections or paths to the SAN? Etc. *a

There are 5 LUN's for this server, each 100GB large. speak to your storage guys, but just because they present 5 LUNS to you doesn't actually mean they are on different spindles.