SQL Performance analysis counters

The important perfmon counters are:

For disk/memory ->
memory: Available MB
memory: Pages/sec

For disks ->
physical disk: avg sec/read (for each disk)
physical disk: avg sec/write (for each disk)
physical disk: avg disk queue length (for each disk) Not really meaningful on a SAN
physical disk: avg % idle time (for each disk)

For Sql ->
SQL Server Buffer manager: Buffer cache hit ratio
SQL Server Buffer manager: checkpoint pages\sec
SQL Server Buffer manager: Lazy writes\sec
SQL Server Memory manager: Total Server memory
SQL Server Memory manager: Target Server memory

most common waits (query sys.dm_os_wait_stats)