Dell PowerVault MD3420 - Manual (Page 122)

NOTE: If you reboot a RAID controller module or make configuration changes to any SSD Cache
options during the modeling run, no data will be saved.
Additional Information About SSD Cache And Performance Modeling
For complete description of the SSD Cache feature, see the Administrator's Guide.
The following additional SSD cache-related commands are available in this document:
• Change SSD Cache Application Type
• Blink SSD Cache
• Rename SSD Cache
• Resume SSD Cache
• Show SSD Cache
• Suspend SSD Cache
Troubleshooting and Diagnostics
If a storage array exhibits abnormal operation or failures, you can use the commands described in this
section to determine the cause of the problems.
Collecting Physical Disk Data
To gather information about all the physical disks in a storage array, run the save allPhysicalDisks
command. This command collects sense data from all the physical disks in a storage array and saves the
data to a file. The sense data consists of statistical information maintained by each of the physical disks in
the storage array.
Diagnosing A RAID Controller Module
The diagnose raidControllerModule 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.
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