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Chapter 6 Checkpoints/Snapshots 6-11
6.1.2.5 Checkpoint Scheduling
Checkpoints can be created in two ways: automatic and manual. If the user selects
the automatic checkpoints, checkpoints are created and removed based on the
scheduling that user specifies for the checkpoints. This scheduling is enforced by a
checkpoint manager thread. On the other hand, checkpoint manager does not control
manually created checkpoints (users can create manual checkpoints that will be
removed automatically by using the same naming convention that system uses for
automatic checkpoints).
Also there is a feature (currently disabled) that allows the root user of an NFS client
to create manual checkpoints. If the root user creates a directory in the root directory
of a CFS, it will be interpreted as a request for creation of a new checkpoint and a
checkpoint with specified name will be created.
6.1.2.6 Checkpoint management commands
In order to manage checkpoints, the following commands are provided in StorEdge
Command Line interface (CLI):
chkpnt : A general command for changing different checkpointing options
chkpntls: Shows the status of checkpoints along with a list of exiting checkpoints
chkpntmk: Creates a new checkpoint
chkpntmv: Renames an existing checkpoint
chkpntoff: Disables checkpoints on a volume. This will remove all the checkpoints
and frees up all the allocated resources
chkpnton: Enables checkpoint on a volume. Does not create any checkpoints
chkpntrm: Removes a checkpoint.
6.1.2.7 Local Directory Checkpoint Access
Checkpoints are read-only point-in-time images of a volume. They can either create
manually or schedule to be create and remove by the system without user
intervention. Checkpoints are accessible in two ways:
■ Via the standard mechanism of mapping or mounting the virtual volume
■ Via the local directory checkpoint access feature
The local directory checkpoint access feature allows the users access any version of a
directory by simply using normal client commands. This white paper describes the
access of checkpoints using the local directory checkpoint access feature and
provides usage examples.