Glossary; Disk Array Terms And Technologies - HP P3410A - NetRAID 1M RAID Controller Installation And Configuration Manual

Glossary

Disk Array Terms and Technologies

Array: An array of disk modules combines the storage space on the disk modules
into a single segment of contiguous storage space. The HP NetRAID adapter can
group disk modules on one or more of its SCSI channels into an array. A hot
spare disk module does not participate in an array.
Array Spanning: Array spanning by a logical drive combines storage space in
up to eight arrays of disk modules into the logical drive's single contiguous
storage space.
Logical drives of the HP NetRAID adapter can span consecutively numbered
arrays that each consist of the same number of disk modules. Array spanning
promotes RAID levels 1 and 5 to RAID levels 10 and 50, respectively.
ASIC: Application Specific Integrated Circuit, a custom designed computer
chip..
BIOS: (Basic Input/Output System) The part of the operating system of the
computer that provides the lowest level interface to peripheral devices. The RAID
BIOS resides on the adapter. The first logical drive of each adapter is loaded into
the system BIOS where it can be used to boot the Netserver. .
Cache Policy: HP NetRAID lets you choose one of two cache policies:
Cached I/O: Reads will always be cached regardless of randomness, and
the selected Read policy (Read Ahead, Normal, or Adaptive) and Write
policy (Write-Through and Write-Back) applies.
Direct I/O: First reads to a new location will always come directly from
the disk. If a location is read repeatedly, then the Read policy (Read
Ahead, Normal, or Adaptive) as selected will apply and the read data will
be cached. Read data is cached only if accessed repeatedly. With 100%
random reads, nothing is cached.
Capacity Expansion (or Volume Expansion): Allows you to increase the size of
an existing volume while remaining online under Microsoft Windows NT or
Windows 2000 or under Novell NetWare 4.2 or 5.x.
Under Microsoft Windows 2000 or NetWare 4.2 or 5.x, leave virtual
sizing disabled to prepare for online capacity expansion.
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