AAA - Adaptec Array Adapter. For example, the AAA-131SA
PCI-Wide Ultra SCSI array adapter.
Array1000CA Family - AAA-131CA represent the Adaptec
Array1000CA Family of Windows NT PC workstation RAID solutions.
Each product offers the same solution through different hardware
means.
Data Caching - Temporary storage of new write data or
high-demand read data in solid state memory in order to accelerate
performance. The cached data is later overwritten with newly
cached data once it is either written to disk or deemed to be of
low demand.
Demand caching - A performance caching technique in which the
currently requested data is read in anticipation of another
request before its allocated blocks are recycled. Reassignment of
the blocks is done on the basis of least recently used (LRU).
EIDE - Enhanced Integrated Drive Electronics. A low cost,
limited functionality drive interface. Controlled by the ANSI
X3T9.2 committee.
Elevator Sort - Data is written to disk in order of increasing
cylinder, head and sector number, minimizing physical disk seeks
and rotational latency.
Fault tolerance - The ability of a system to continue to
perform its functions, even when one or more components have
failed.
Mirroring - Also known as RAID 1 or duplexing (when using two
host bus adapters). Full redundancy is obtained by duplicating all
data from a primary disk on a secondary disk. The overhead of
requiring 100% data duplication can get costly when using more
than two drives.
Multitasking - The ability for the operating system to perform
multiple operations at once. Windows NT Workstation is a
multitasking operating system which can perform multiple I/O
requests at once. SCSI and a Caching RAID coprocessor take
advantage of multitasking.
PCI - Peripheral Component Interconnect. Industry-standard
specification that refers to a high-speed (133 MB/sec) host bus
commonly used for host adapters, Ethernet adapters, and video
cards.
Pre-fetching - Intelligent gathering of data from disks prior
to requests from the operating system.
RAID - Redundant array of inexpensive disks. The term coined in
1987 by researchers at the University of California at Berkeley to
describe a series of redundant architectures used in
fault-tolerant disk arrays.
Read-ahead Caching - A performance caching technique in which
data is anticipated and read into the cache before it is actually
requested.
SCSI - Small Computer System Interface (pronounced scuzzy). The
fast, intelligent input/output parallel bus used by
high-performance peripherals.
S.M.A.R.T. - Self-Monitoring, Analysis and Reporting Technology
Drives equipped with this feature report predicted failures based
on threshold values determined by the manufacturer. This allows
the network manager to replace a drive before it fails.
Striping - Also known as RAID 0. Two or more drives store and
retrieve data in parallel, accelerating performance.
Tagged Command Queuing - A feature in SCSI that enables disk
drives and I/O adapters to send multiple commands prior to
completion of a given command.
Write-back caching - A performance caching technique in which
the completion of a write request is signaled as soon as the data
is in cache. Actual writing to the disk occurs at a later time.
Write-through caching - A caching technique in which the
completion of a write request is not signaled until data is safely
stored on disk.
