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Glossary
The following terms are used throughout this manual and may be helpful
background information on the technology.
Asynchronous
Operations Operations that bear no relationship to each other in time
and can overlap. The concept of asynchronous I/O
operations is central to independent access arrays in
throughput-intensive applications.
Cache Flush Refers to an operation where all un-written blocks in a
Write-Back Cache are written to the target disk. This
operation is necessary before powering down the system.
Channel Refers to one of the SCSI bus connectors on the
controllers or termination interface cards.
Consistency Check Refers to a process where the integrity of redundant data
is verified. For example, a consistency check of a mirrored
drive will make sure that the data on both drives of the
mirrored pair are exactly the same. For RAID level 3 and 5
redundancy, a consistency check will involve reading all
associated data blocks, computing parity, reading parity,
and verifying that the computed parity matches the read
parity.
Disconnect/Reconnect Disconnect is a function that allows a target SCSI device
(typically a disk drive that received a request to perform a
relatively long I/O operation) to release the SCSI bus so
that the controller can send commands to other devices.
When the operation is complete and the SCSI bus is
needed by the disconnected target again, it is reconnected.