HP StorageWorks SAN Virtualization Services Platform Manager command line interface user guide (AG781-96016, March 2009)

The successful completion of a command in this context means that:
• If the API or CLI successfully creates a VSM object (virtual disk, PiT, snapshot, snapclone group,
and so on), this newly created object is ready to be used when the API/CLI returns. For example,
if you create a PiT, you can immediately proceed to create a snapshot on this PiT.
• If the API or CLI successfully deletes one or more VSM objects, then after the API or CLI returns,
you can create new objects with the same names as those just deleted.
This mode of operation is referred to as a synchronous mode, since the application (or CLI) is blocked
until the operation is completed.
NOTE:
The recommended timeout value to use for most operations is 900 (seconds). For some operations
(create a PiT or snapshot, delete PiT, restore snapshot), it is recommended you use even higher values,
since the time they take to complete depends on how much data they need to handle.
There is also an asynchronous mode of operation for APIs and CLI commands that creates VSM objects
like virtual disk, PiT, snapshot, PiT/snapshot on a virtual disk group, and so on. In this mode of
operation, you use the same API or CLI as before, with only one change: The timeout value is set to
zero. Under this condition, the API or CLI starts the operation but does not wait for it to complete. So
if the API or CLI returns without an error, it means that the operation was started successfully, but has
not necessarily been completed yet.
There is an additional API or CLI function that is used to wait for the completion of such operations:
WaitForObjectCreation.
The list of the above mentioned creation operations include CreateVirtualDisk, CreatePiT,
CreateSnapshot, CreateVDGroupPiT, CreateVDGroupSnapshot,
CreateAsyncMirrorUserPiT, and CreateVDGroup.
For example, if you need to create n PiTs, then instead of waiting for each PiT to become ready for
use consecutively, one after the other (which may take n times per PiT), you can create all the PiTs
with no timeout and then call n times the WaitForObjectCreation API/CLI, once for every PiT.
Since the creation of all PiTs has already started, you need to wait only as long as it takes for the
longest PiT to be created.
In addition, when working with the APIs in synchronous mode, if the timeout is too small and the API
returns with an VSM_SYNC_TIMEOUT error, you can use this API to wait for the completion of the
operation.
Virtual disks in DPM groups
Virtual disks that belong to a virtual disk group (VDG) are always presented to a host through a
specific Data Path Module (DPM) group. The VSM GUI has an internal algorithm that assigns a virtual
disk to the DPM group, therefore the VSM CLI cannot be used to assign a virtual disk to a specific
DPM group. If a host is assigned to more than one DPM group, then use the VSM GUI and not the
CLI to make virtual disk presentations.
HP StorageWorks SAN Virtualization Services Platform Manager command line interface user
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