The SAN world is one measured in IOPs. That is not a database friendly measurement. Even using local or direct attached storage it is difficult to determine maximum throughput. Activity Monitor allows you to see activity in MB/sec. So how fast can you read from your database?
One way is to do a database backup to a null device. Take a large database and back it up to ‘NUL’
BACKUP DATABASE [DBName] TO DISK = ‘NUL’ WITH STATS=10
If you are using SQL 2008 you can try with compression.
BACKUP DATABASE [ReportServer] TO DISK = ‘NUL’ WITH COMPRESSION WITH STATS=10
The results return a MB/sec rate and you can watch the backup in Activity Monitor.