HP 8.20q Fibre Channel Switch - Manual (Page 142)

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Vraid0 A virtualization technique for EVA storage 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 for EVA storage 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 for EVA storage 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.
Vraid6 Vraid6 has the highest availability of any Vraid type. It uses dual parity to provide protection
from simultaneous failure of two disk drives within a parity stripe. Vraid6 stripes have four data
blocks and two parity blocks. A new disk group type has been added to facilitate Vraid6
support. The enhanced disk group can simultaneously contain virtual disks of all supported
Vraid types. The legacy disk group type supports all Vraid types except for Vraid6. The disk
group type is set at the time of creation and cannot be changed after that time.
Note: Simple SAN Connection Manager supports Vraid6 only for the EVA4400/6400/8400
running firmware version 9500000 or later.