Each logical volume in a volume group is considered to be a component with which hosts can perform
I/O. Logical volumes can contain file systems or be raw storage. See
LUN
In each storage system, logical unit numbers (LUNs) are assigned to its virtual disks. When a virtual disk
is presented to hosts, the storage system and the hosts perform I/O by referencing the LUN.
At a low level, a host OS typically reports each storage device that it detects in the format of C# T#
D#, where:
C #
Identifies a host I/O controller
T #
Identifies the target storage system on the controller
D #
Identifies the virtual disk (LUN) on the storage system
Automatic LUN assignment
•
When presenting a virtual disk to a host, enter zero (0) to allow the storage controller software to
automatically assign the LUN.
Mirrorclones - fractured
Mirrorclone replication establishes and maintains a copy of a original virtual disk, via a local replication
link. See virtual disk types.
source
When the local replication between a synchronized mirrorclone and its source is stopped by an action or
command, the mirrorclone is said to be fractured. In a fractured state, the mirrorclone is not updated
when the source virtual disk is updated. At the instant replication is stopped, the mirrorclone is a
point-in-time copy of its source. See also
Task summary for fractured mirrorclones
Fractured mirrorclones
Deleting
Detaching
Fracturing
Presenting
Replicating - snapclones
Replicating - snapshots
Restoring
Resynchronizing
See also general
Mirrorclone write-cache flush
The source virtual disk write cache must be flushed before a fracture is started. (See cache policies
write
cache.) This ensures that the source virtual disk and its mirrorclone contain identical data when the
fracture occurs. The following table shows how a write cache flush is implemented.
142
Host volumes
=====||=====
local link
mirrorclone states
No. The disk must first be detached, then deleted.
Yes.
Not applicable.
Yes. The disk can immediately be presented to hosts for I/O.
No.
Yes. Multiple snapshots are allowed.
Yes. The disk must be unpresented first.
Yes. The disk must be unpresented first.
mirrorclone guidelines
and
mirrorclone
(fractured)
and
synchronized
mirrorclone
FAQ.
raw
disks.
mirrorclones.