User's Manual

Glossary 81
Coercion Mode
A controller property indicating the size to which disk drives of nominally
identical capacity are coerced (forced) in order to make them usable in a storage
configuration.
consistency check
An operation that verifies that all stripes in a virtual disk with a redundant RAID
level are consistent and that automatically fixes any errors. For RAID 1 disk
groups, this operation verifies correct mirrored data for each stripe.
Consistency Check Rate
The rate at which consistency check operations are run on a computer system.
controller
A chip that controls the transfer of data between the microprocessor and
memory or between the microprocessor and a peripheral device such as a
physical disk. RAID controllers perform RAID functions such as striping and
mirroring to provide data protection. Dell SAS RAID Storage Manager runs on
the Dell PERC 5/i, PERC 6/i, SAS 5/iR, and SAS 6/iR controllers.
Current Write Policy
A virtual disk property that indicates whether the virtual disk currently supports
Write back or Write through mode.
• In Write back mode the controller sends a data transfer completion
signal to the host when the controller cache has received all the data in a
transaction.
• In Write through mode the controller sends a data transfer completion
signal to the host when the disk subsystem has received all the data in a
transaction.
Default Write Policy
A virtual disk property indicating whether the default write policy is Write
through
or Write back . In Write back mode the controller sends a data transfer
completion signal to the host when the controller cache has received all the data
in a transaction. In Write through mode the controller sends a data transfer
completion signal to the host when the disk subsystem has received all the data
in a transaction.