Drive Performance Monitoring; Types Of Dpm Statistics; Available Dpm Commands - 3Ware 9550SXU-12 User Manual

Drive Performance Monitoring

Types of DPM Statistics

Available DPM Commands

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When one drive in a RAID unit is responding much slower than others, it
reduces the performance of the entire unit.
Drive Performance Monitoring (DPM) is now available to measure drive
performance, and to help identify when a specific drive is causing problems
so that you can have the drive manufacturer repair or replace it.
DPM is an advanced trouble-shooting tool. Commands are available through
the 3ware CLI to enable and disable DPM, and to see a range of different
statistics. These statistics can be useful to AMCC technical support to help
you troubleshoot problems with your RAID controller and units.
The following drive statistical data can be stored and reported:
• Queue depth, which indicates the number of read/writes that are
currently outstanding.
• IOP, which indicates the number of read/writes that have completed
• Transfer rate, which indicates the number of sectors that have been read/
written
• Response time, which indicates the execution time of all commands
• Command read/writes, which indicates the drive and drive sectors'
accumulated read and write commands.
Drive Performance Monitoring commands are available through the CLI. An
overview of the commands is provided below. For more information about the
command syntax and for examples of the report output, see the CLI Syntax
Reference in the 3ware SAS/SATA RAID Controller CLI Guide.
• . This starts the collection of statistics for drives attached to
Enable DPM
your RAID controller. (/cx dpmstat=on).
For efficient collection of data, initiate read/write activity on the specified
controller. The numbers will change over time as the new and old data are
averaged.
• . This stops the collection of statistics. (/cx dpmstat=off)
Disable DPM
DPM is disabled by default since there is overhead in maintaining the
statistics. DPM is also disabled following a reboot or power-on. Turning
off DPM does not clear the statistical data that has been recorded. To clear
the data, use the command /cx/px set dpmstat=clear [type=ra|lct|ext].
Drive Performance Monitoring
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