Select this parameter:

If you want to:

CPU

Monitor the CPU state on the SQL host.

Memory

Monitor free memory on the SQL host.

Disk

Monitor disk usage on the SQL host by the SQL server.

Disk space

Monitor free disk space on the SQL host.

System

Monitor system processes on the SQL host.

Buffers

Monitors SQL page buffers.

Cache

Monitors cache usage on the SQL server.

Locks

Monitors wait locks on the SQL server.

Transactions

Monitors the transactions on the SQL server.

Users

Monitors the users on the SQL server.

Alerts

Monitors SQL alerts and severity of alerts.

Custom Thresholds

Browse and select from the large number of additional parameters that SQL reports.