HP StorageWorks 6000-series Virtual Library System User Guide (AH809-96049, September 2010)

initiator A media (host) server that runs the backup/restore application that passes
commands and data between the network and the VLS.
inputs/outputs per
second
A performance measurement for a host-attached storage device or RAID controller.
library A storage device that handles multiple units of media and provides one or more
drives for reading and writing them, such as a physical tape library and virtual
tape library. Software emulation of a physical tape library is called a virtual tape
library.
logical unit
number (LUN)
An address used in the SCSI protocol to access a device within a target. In the
case of the VLS, a LUN is assigned to each virtual library and tape drive.
LUN mapping A mechanism of changing the LUN assignments for a specific host.
LUN masking An authorization process that makes a LUN available to some hosts and
unavailable to other hosts.
mean time until
data loss (MTDL)
The average time until a component failure can be expected to cause data loss.
This includes the consideration that RAID redundancy can protect against data
loss from the failure of a single component.
media access
control (MAC)
address
A low-level unique hardware identifier for every Ethernet port in the world that
is physically stored inside a network card or similar network interface. MAC
addresses are assigned by the IEEE.
media server A computer whose purpose is to move or copy data from one location to another,
such as from network clients to tape cartridges in a library.
node A server that contains the hardware and firmware required to run a virtual library
system. This refers to a hardware assembly containing a power supply, cooling
fans, motherboard, expansion boards, and internal hard drives to support the
VLS system.
oversubscription A condition that exists when more virtual media storage is configured on a VLS
than there is physical storage available.
Because the VLS dynamically allocates storage space as user data is written, the
VLS allows you to allocate more storage for virtual media than is physically
available.
RAID A RAID volume consists of more than one drive, but appears to the operating
system to be a single logical disk. RAID improves performance by disk striping,
which involves partitioning each drive's storage space into units. By placing data
on multiple disks, I/O operations can overlap in a balanced way, improving
performance.
RAID1-level data
storage
A RAID that consists of at least two drives that use mirroring (100 percent
duplication of the storage of data). There is no striping. Read performance is
improved since either disk can be read at the same time. Write performance is
the same as for single disk storage.
RAID5-level data
storage
A RAID that provides data striping at the byte level and also stripe error correction
information. RAID5 configurations can tolerate one drive failure. Even with a
failed drive, the data in a RAID5 volume can still be accessed normally.
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