How They Occur Combination failures occur when a catastrophic drive failure occurs
while there are still undetected, uncorrected sector media errors on the remaining drives in the array,
the adapter cannot rebuild all the data.
In such cases, a double failure exists, files must be restored from backup media.
See Combination Failure for information about protection provided at the ServeRAID adapter level.
IBM recommends data scrubbing all RAID-5 and RAID-1 logical drives weekly, or updating firmware to a level which provides automatic data scrubbing, to minimize the risk of having any undetected sector media errors on the remaining drives of the array when a drive failure occurs.
Note: IBM provides management software, Netfinity Manager, with IBM servers that ship with ServerGuide.
The software monitors the status of the hardware and provides alerts when conditions are not optimal.
Netfinity Manager enables customers to obtain all of the information necessary for data protection.
Installation of Netfinity Manager or similar tools to monitor and track disk subsystem integrity is critical for the protection of stored data.