Redundancy Level (Vraid); Snapclones - HP 418800-B21 - StorageWorks Modular Smart Array 70 Storage Enclosure User Manual

• Cannot be a snapshot or a mirrorclone. See virtual disks types.
• Cannot have a mirrorclone. This restriction is controller software version dependent. See
controller software features - remote
• Must be in a normal operational state. See resources
• Must use mirrored cache. See virtual disks
• Must have the same presentation status as other virtual disks in the DR group. With some
versions of controller software, the virtual disk must be presented to a host. See storage
systems

Redundancy level (Vraid)

Redundancy level (Vraid) refers to the method and extent of RAID data protection for a virtual disk. Vraid
levels are defined as follows:
Type
Vraid1
Vraid5
Vraid0
Vraid is the HP StorageWorks implementation of RAID on Enterprise Virtual Arrays. However, unlike
traditional RAID, all Vraid levels distribute data blocks across multiple physical disks in the disk group.
Once a virtual disk or container is created, its Vraid level cannot be changed.

Snapclones

Snapclone replication instantly creates an independent, point-in-time copy of a virtual disk. The copy
begins as a fully allocated snapshot, and then automatically becomes an independent virtual disk. The
copy is called a snapclone. See also virtual disks
The snapclone property indicates whether a virtual disk can be locally replicated using the snapclone
method. Values are:
• Yes. The virtual disk complies with snapclone guidelines. Snapclone replication can be performed.
• No. The virtual disk does not comply with snapclone guidelines. Snapclone replication cannot
be performed.
Preallocated snapclones
Preallocated snapclone refers to a snapclone that is created by copying data from a source virtual disk
to a container and immediately converting the container into a virtual disk. Compared to a standard
snapclone, creating a preallocated snapclone is faster. In cases where host I/O must be suspended, the
improved speed of preallocated snapclones reduces the time that a host application is suspended.
When a preallocated snapclone is created, the source virtual disk write cache must be flushed before
replication is started. (See cache policies
snapclone copy contain identical data. The following table shows how a write cache flush is implemented.
IMPORTANT:
When using jobs or the CLUI, you must explicitly ensure that write caches are flushed.
438
Virtual disks
controller software features - remote
Redundancy
High
Medium
None
replication.
operational
cache policies.
replication. See also virtual disks presentation.
Technique Remarks
Optimized for redundancy and speed,
Mirroring but requires twice the disk space of
other levels.
Provides a balance of redundancy,
Striping and parity
speed, and disk space.
Optimized for speed and disk space,
but provides no redundancy.
IMPORTANT:
Striping
HP does not recommend using Vraid0
when high availability is required.
snapclone FAQ
write cache.) This ensures that the source virtual disk and
states.
and snapclone guidelines.