Instruction Manual

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 cach ed
data
Also called unflushed data.
See also dir ty data.
UPS Uninterruptible Power Supply. A battery-operated power supply gua ranteed to
provide power to an electrical device in the event of an unexpected interruption
to the primary power supply. Uninterruptible power supplies a re 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 virtua l 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 d isk.
See also active virtual disk, virtual disk copy, virtual disk family,andvirtual
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 im m ediately becomes the
active disk of its own virtual disk family.
See also active virtual disk, virtual disk family,andvirtual disk snapshot
virtual disk family A virtual disk and its snapshot, if a snapshot exists, constitute a family. The
original virtual disk is c alled the active disk. When you firstcreateavirtualdisk
family, the only member is the active disk.
See also active virtual disk, virtual disk copy,andvirtual disk snapshot.
virtual disk snap-
shot
See snapshot.
Vraid0 A virtualization technique that provides no data protection. Da ta 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 a nd 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 incre ase
performance. Mirroring takes the most storage space because t wice the storage
capacity must be allocated for a given amount of data.
Vraid5 A virtualiza tion technique that uses parity striping to provide moderate data
protection. Parity is a data protection mechanism for a striped virtual disk. A
striped virtual d isk is one where the data to a nd 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 da ta chunks and written to
the physical d isks. If one of the data chunks becomes c orrupted, 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 (VCS 3.110)
179