Dell PowerVault MD 32XX/36XX Series Storage Arrays CLI Guide

The diagnose controller command’s testID parameter takes the following options, which you can use to verify that a RAID controller module is functioning correctly:

1	Reads the test
2	Performs a data loop-back test
3	Writes the test

The read test initiates a read command as it would be sent over an I/O data path. The read test compares data with a known, specific data pattern, checking for data integrity and errors. If the read command is unsuccessful or the data compared is not correct, the RAID controller module is considered to be in error and is placed offline.

Run the data loopback test only on RAID controller modules that have connections between the RAID controller module and the physical disks. The test passes data through each RAID controller module physical disk-side channel out onto the loop and back again. Enough data is transferred to determine error conditions on the channel. If the test fails on any channel, this status is saved so that it can be returned if all other tests pass.

The write test initiates a write command as it would be sent over an I/O data path to the diagnostics region on a specified physical disk. This diagnostics region is then read and compared to a specific data pattern. If the write fails or the data compared is not correct, the RAID controller module is considered to be in error, and it is failed and placed offline.

For best results, run all three tests at initial installation. Also, run the tests any time you make changes to the storage array or to components connected to the storage array (such as hubs, switches, and host adapters).

Events are written to the MEL when diagnostics are started and when testing is completed. These events help you to evaluate whether diagnostics testing was successful or failed and the reason for the failure.