American Megatrends MegaRAID Express 500 Manual Do Utilizador
Glossary
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Glossary
Array
A grouping or array of disk drives combines the storage space on the disk drives
into a single segment of contiguous storage space. MegaRAID can group disk
drives on one or more SCSI channels into an array. A hot spare drive does not
participate in an array.
into a single segment of contiguous storage space. MegaRAID can group disk
drives on one or more SCSI channels into an array. A hot spare drive does not
participate in an array.
Array Management Software Software that provides common control and management for a
disk array. Array Management Software most often executes in a disk controller
or intelligent host bus adapter, but can also execute in a host computer. When it
executes in a disk controller or adapter, Array Management Software is often
called firmware.
or intelligent host bus adapter, but can also execute in a host computer. When it
executes in a disk controller or adapter, Array Management Software is often
called firmware.
Array Spanning Array spanning by a logical drive combines storage space in two arrays of disk
drives into a single, contiguous storage space in a logical drive. MegaRAID
logical drives can span consecutively numbered arrays that each consist of the
same number of disk drives. Array spanning promotes RAID levels 1, 3, and 5 to
RAID levels 10, 30, and 50, respectively. See also Disk Spanning.
logical drives can span consecutively numbered arrays that each consist of the
same number of disk drives. Array spanning promotes RAID levels 1, 3, and 5 to
RAID levels 10, 30, and 50, respectively. See also Disk Spanning.
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.
access arrays in throughput-intensive applications.
Cache I/O
A small amount of fast memory that holds recently accessed data. Caching
speeds subsequent access to the same data. It is most often applied to processor-
memory access, but can also be used to store a copy of data accessible over a
network. When data is read from or written to main memory, a copy is also
saved in cache memory with the associated main memory address. The cache
memory software monitors the addresses of subsequent reads to see if the
required data is already stored in cache memory. If it is already in cache memory
(a cache hit), it is read from cache memory immediately and the main memory
read is aborted (or not started.) If the data is not cached (a cache miss), it is
fetched from main memory and saved in cache memory.
speeds subsequent access to the same data. It is most often applied to processor-
memory access, but can also be used to store a copy of data accessible over a
network. When data is read from or written to main memory, a copy is also
saved in cache memory with the associated main memory address. The cache
memory software monitors the addresses of subsequent reads to see if the
required data is already stored in cache memory. If it is already in cache memory
(a cache hit), it is read from cache memory immediately and the main memory
read is aborted (or not started.) If the data is not cached (a cache miss), it is
fetched from main memory and saved in cache memory.
Channel
An electrical path for the transfer of data and control information between a disk
and a disk controller.
and a disk controller.
Cont’d