NSM5200: HDD response time monitoring on 3Ware controllers

Issue

Drive performance needs to be gauged

Product Line

Pelco Video Management

Environment

NSM5200 all versions

Cause

  • Underlying hardware incompatibility between unsupported third party drives and the 3ware 9690SA and 9750 Controller cards.
  • The official answer is that we do not recommend mixed models of hard drives on an NSM5200. The reason being is that it degrades performance on the RAID controller which increases the possibility of recording gaps. Note: Not everyone will have this problem because each system is configured differently the performance impacts will vary when drives are mixed.
  • 3Ware/LSI have also published HDD Compatibility Lists, which can be found here.

Resolution

The drive response time monitoring utility is called dpmstat. Substitute /cX with the controller number specific to your NSM5200.

To enable performance monitoring run the following command:
tw_cli /cX set dpmstat=on

To disable performance monitoring run the following command:
tw_cli /cX set dpmstat=off

To output the data that has been collected, as well as show if the performance monitoring is turned on, run the following command:
tw_cli /cX show dpmstat

  • Keep in mind that the data being collected is a snapshot of the performance only for the duration that dpmstat has been enabled.
  • Be aware of the current system load prior to running this as it will affect the overall system performance.
  • Turn off dpmstat once the data has been gathered.

To output individual drive performance data run the following command:
tw_cli /cX/pX show dpmstat type=histdata

  • Substitute /pX with the drive port number you wish to retrieve data for.

Additional info regarding dpmstat can be found here.