Apple Xsan 2 (Third Edition) - Manual (Page 124)

124 Glossary
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.
fill An Xsan storage pool allocation strategy. In a volume consisting of more than one
storage pool, Xsan fills up the first pool before writing to the next.
format (verb) In general, to prepare a disk for use by a particular file system.
FSS File system server. The StorNext File System term for the computer that manages
metadata in a storage area network (SAN). In Xsan, this is called a metadata controller.
initialize To prepare a disk for use by a particular file system. In Xsan, to prepare a
RAID array for use in a storage pool.
label (noun) In Xsan, an identifying name for a LUN. You can assign a label to a LUN
before or during setup of an Xsan storage pool.
label (verb) Used by some sources (such as StorNext) to refer to the process of
preparing a logical disk for use with a file system. In Xsan, however, initialize is used to
refer to preparing a disk for use in a storage pool.
logical disk A storage device that appears to a user as a single disk for storing files,
even though it might actually consist of more than one physical disk drive. An Xsan
volume, for example, is a logical disk that behaves like a single disk even though it
consists of multiple storage pools that are, in turn, made up of multiple LUNs, each of
which contains multiple disk drives. See also physical disk.
LUN Logical unit number. A SCSI identifier for a logical storage device. In Xsan, an
unformatted logical storage device such as an Xserve RAID array or slice.
metadata Information about a file system and the files it stores (for example, which
disk blocks a file occupies or which blocks are available for use). In Xsan, metadata is
managed by a metadata controller and exchanged over an Ethernet connection, while
actual file data is transferred over a Fibre Channel connection.
metadata controller The computer that manages metadata in an Xsan storage area
network.
mount (verb) To make a remote directory or volume available for access on a local
system. In Xsan, to cause an Xsan volume to appear on a client’s desktop, just like a
local disk.
physical disk An actual, mechanical disk. Compare with logical disk.
RAID Redundant Array of Independent (or Inexpensive) Disks. A grouping of multiple
physical hard disks into a disk array, which either provides high-speed access to stored
data, mirrors the data so that it can be rebuilt in case of disk failure, or both. The RAID
array is presented to the storage system as a single logical storage unit. See also RAID
array, RAID level.