HP 3000 Enterprise Virtual Array - Manual (Page 153)

may be incapable of recovering or bypassing the failure and will require repairs
to correct the condition.
This is the highest level condition and has precedence over all other errors and
requires immediate corrective action.
unwritten cached
data
Also called unflushed data.
See also dirty data .
UPS Uninterruptible Power Supply. A battery-operated power supply guaranteed to
provide power to an electrical device in the event of an unexpected interruption
to the primary power supply. Uninterruptible power supplies are usually rated
by the amount of voltage supplied and the length of time the voltage is supplied.
Vdisk Virtual Disk. A simulated disk drive created by the controllers as storage
for one or more hosts. The virtual disk characteristics, chosen by the storage
administrator, provide a specific combination of capacity, availability,
performance, and accessibility. A controller pair simulates the characteristics
of the virtual disk by deploying the disk group from which the virtual disk was
created.
The host computer sees the virtual disk as “real,” with the characteristics of an
identical physical disk.
See also active virtual disk , virtual disk copy , virtual disk family , and virtual
disk snapshot .
virtual disk See Vdisk .
virtual disk copy A clone or exact replica of another virtual disk at a particular point in time.
Only an active virtual disk can be copied. A copy immediately becomes the
active disk of its own virtual disk family.
See also active virtual disk , virtual disk family , and virtual disk snapshot
virtual disk family A virtual disk and its snapshot, if a snapshot exists, constitute a family. The
original virtual disk is called the active disk. When you first create a virtual disk
family, the only member is the active disk.
See also active virtual disk , virtual disk copy , and virtual disk snapshot .
virtual disk snap-
shot
See snapshot .
Vraid0 A virtualization technique that provides no data protection. Data host is broken
down into chunks and distributed on the disks comprising the disk group from
which the virtual disk was created. Reading and writing to a Vraid0 virtual disk
is very fast and makes the fullest use of the available storage, but there is no
data protection (redundancy) unless there is parity.
Vraid1 A virtualization technique that provides the highest level of data protection.
All data blocks are mirrored or written twice on separate physical disks. For
read requests, the block can be read from either disk, which can increase
performance. Mirroring takes the most storage space because twice the storage
capacity must be allocated for a given amount of data.
Vraid5 A virtualization technique that uses parity striping to provide moderate data
protection. Parity is a data protection mechanism for a striped virtual disk. A
striped virtual disk is one where the data to and from the host is broken down
into chunks and distributed on the physical disks comprising the disk group in
which the virtual disk was created. If the striped virtual disk has parity, another
chunk (a parity chunk) is calculated from the set of data chunks and written to
the physical disks. If one of the data chunks becomes corrupted, the data can
be reconstructed from the parity chunk and the remaining data chunks.
World Wide
Name
See WWN .
Enterprise Virtual Array 3000/5000 user guide 153