HP Command View EVA Software - Manual (Page 36)

Vraid overview
Vraid is an HP term for implementing RAID storage (Redundant Array of Independent Disks). Virtual
disks with HP Vraid use three key RAID methods: data striping, data mirroring, and parity error
checking.
Data striping improves speed by performing virtual disk I/O with an entire group of physical disks
at the same time. Data mirroring provides data redundancy by storing data and a copy of the
data. Parity error checking provides automatic detection and correction if corruption of a physical
disk occurs. Unlike traditional RAID, all HP P6000 Vraid levels distribute data across all available
physical disks.
HP P6000 SmartStart supports the following Vraid types or levels: Vraid0 , Vraid1 , Vraid5 and
Vraid6 . Each type uses a different combination of RAID methods that impact data redundancy,
the amount of physical disk space used, and I/O speed.
Once a virtual disk is created, its Vraid type cannot be changed. The following summaries can
help you choose an appropriate type.
RAID
method
Data
redundancy Best Practices Summary
Striping None
IMPORTANT: HP does not
recommend using Vraid0 for virtual
disks when high availability is
required. Consider Vraid0 only for
noncritical storage.
Vraid0 (striping) and is optimized
for speed and disk space
utilization but does not provide
any redundancy. Vraid0
Vraid0 virtual disks provide the best
performance for applications that
use random I/O.
Mirroring High In general, Vraid1 virtual disks
provide better performance Vraid1 (striping with mirroring) is
optimized for speed and high data Vraid1
characteristics over a wider range redundancy. A Vraid1 virtual disk
of application workloads than
Vraid5. can automatically recover
(reconstruct) from the failure of one
physical disk.
Vraid1 uses about twice the
physical disk space of Vraid0.
Striping and
parity
Medium Vraid5 virtual disks provide as good
or better performance than Vraid1 Vraid5 (striping with parity) is
optimized for speed, disk space Vraid5
for applications that use sequential utilization, and moderate
writes. Vraid5 has much lower redundancy. A Vraid5 virtual disk
random write performance in can automatically recover
comparison to Vraid1, but has much
higher capacity efficiency. (reconstruct) from the failure of one
physical disk.
Vraid5 uses about 20% more
physical disk space than Vraid0.
Striping and
dual parity
Highest Performance characteristics of
Vraid6 for random or sequential Vraid6 (striping with dual parity)
is optimized for speed and the Vraid6
write workloads will be slightly highest redundancy. A Vraid6
lower than Vraid5. Vraid6 provides virtual disk can automatically
the highest level of redundancy
protection of all Vraid types. recover (reconstruct) from the
concurrent failure of two physical
disks. Vraid6 support is dependent
on the controller software version.
See the HP P6000 Enterprise
Virtual Array Compatibility
Reference.
Vraid6 uses about 33% more
physical disk space than Vraid0.
36 HP P6000 SmartStart concepts