Name Type Description Mandatory Default
overwrite Object name Existing snapshot
group which is
overwritten with
current content.
N N/A
auto_
resume
Positive integer Indication whether
to resume IO to
the Consistency
Group by
providing the
token ID.
N0
This command creates a consistent snapshot group from a Consistency Group,
which includes a snapshot for each of the volumes contained in the Consistency
Group.
Logically, this command is comprised of the following steps:
v Suspending all I/O activity on all the volumes in the group and waiting for all
pending I/Os to complete
v Creating a snapshot for each of the volumes in the group
v Resuming I/O activity on all the volumes
The main advantage of using this command (as opposed to a manual procedure) is
that all snapshots are taken at the same point in time, thus ensuring that they are
consistent with each other.
The snapshots in the created snapshot group are consistent with respect to each
other in the following manner:
v All snapshots are created synchronously at the same point in time.
v With respect to this point in time, all I/Os to the Consistency Group's volumes
that were completed previously are recorded in the snapshot's image.
v All I/Os that were completed afterwards are not recorded in the snapshot's
image.
All the snapshots in the snapshot group are also associated with the Consistency
Group in addition to having their regular attributes.
The name of the snapshot group is either automatically generated or provided in
the command line.
The delete priority of the snapshots in the snapshot group can also be provided
(see Creating a Snapshot). The delete priority controls which snapshots or snapshot
groups are deleted first when the system runs out of space for snapshots.
The overwrite option causes the current content of the Consistency Group to be
copied into one of its existing snapshot groups (the argument of overwrite). The
snapshots of the overwritten snapshot group keep the same SCSI serial number
and same mapping, so hosts maintain a continuous mapping of the snapshots,
without any need for a rescan or similar operation. The overwrite snapshot group
must be an existing snapshot group of the given Consistency Group.
This command fails if no snapshot space is defined for the Storage Pool containing
the Consistency Group.
102 IBM XIV Storage System User Manual
To Next Page
Loading...
Need help?
General
