Apple Xsan 1.1 - Manual (Page 127)

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Glossar
y Glossary
affinity A relationship between a folder on an Xsan volume and one of the storage
pools that provide storage for the volume. The affinity guarantees that files placed in
the folder are stored only on the associated storage pool. Storage pools can differ in
capacity and performance, and affinities can be used to assure that data such as video,
which requires high transfer speed, is stored on the fastest storage devices.
allocation strategy In Xsan, the order in which data is written to the storage pools that
make up a volume. Applicable only if there’s more than one storage pool in a volume,
and only if the pools are of the same class. Can be fill, round robin, or balance.
balance An Xsan storage pool allocation strategy. Before allocating space on a volume
consisting of more than one storage pool, Xsan checks available storage on all pools,
then uses the one with the most free space.
block allocation size An Xsan volume property. The smallest number of bytes that can
be reserved on, written to, or read from an Xsan volume.
client A computer (or a user of the computer) that requests data or services from
another computer, or server.
controller In an Xsan storage area network, short for metadata controller.
See metadata controller. In RAID systems, controller refers to hardware that manages
the reading and writing of data. By segmenting and writing or reading data on
multiple drives simultaneously, the RAID controller achieves fast and highly efficient
storage and access.
failover In Xsan, the automatic process by which a standby metadata controller
becomes the active metadata controller if the primary controller fails.
failover priority In a SAN with more than one controller, specifies which standby
controller to try first during failover.
file system A scheme for storing data on storage devices that allows applications to
read and write files without having to deal with lower-level details.
file system server See FSS.