Dell PowerVault MD3260 CLI Guide - Page 84

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 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). A custom data pattern file called diagnosticsDataPattern.dpf is included on the Utility directory of the installation CD. You can modify this file, but the file must have the following properties to work correctly for the tests: • The file values must be entered in hexadecimal format (00 to FF) with only one space between the values. • The file must be no larger than 64 bytes in size. Smaller files can be used, but larger files can cause an error. The test results contain a generic, overall status message and a set of specific test results. Each test result contains the following information: • Test (read/write/data loopback) • Port (read/write) • Level (internal/external) • Status (pass/fail) 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. Recovery Operations Recovery operations involve replacing failed RAID controller modules and physical disks, restoring data, and restoring the storage array to operation. 84