Silicon Graphics InfiniteStorage 4000 Series, Настройка и обслуживание

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Chapter 6: Using the Snapshot Images Premium Feature 117

You cannot increase or decrease the repository capacity for a snapshot volume
that is read-only because it does not have an associated repository. Only snapshot
volumes that are read-write require a repository.

When you decrease capacity for a snapshot volume or a consistency group
member snapshot volume, the system automatically transitions the volume to a
Disabled state.
To decrease the size of a repository volume use one of these commands:
 set snapVolume ["snapVolumeName"]
decreaseRepositoryCapacity count=numberOfVolumes
 set snapGroup ["snapGroupName"]
decreaseRepositoryCapacity count=numberOfVolumes
Starting,
Stopping, and
Resuming a
Snapshot Image
Rollback Snapshot images are useful any time you need to be able to roll back to a known good
data set at a specific point in time. For example, before performing a risky operation
on a volume, you can create a snapshot image to enable “undo” capability for the
entire volume. You can start a rollback from the following types of snapshot images:

Snapshot image of a base volume, which allows you to roll back the base volume
associated with a snapshot group to a previous state.

Consistency group snapshot image, which allows you to roll back all or select
member volumes of the consistency group to a previous state.
The snapshot image rollback commands provide a way for you to manage the content
that is maintained by snapshot groups and snapshot consistency groups. A snapshot
image rollback operation enables you to restore the contents of a base volume to a
point-in-time image that was captured when a snapshot image was created. The base
volume is then immediately accessible for read/write operation using the rolled-back
content after the controller firmware accepts the rollback request. The read/write
operation can take place while the rolled-back content is being transferred to the base
volume.
You can roll back data by performing one of these operations:

Creating a snapshot volume of a snapshot image, which allows you to retrieve
deleted files from that snapshot volume (the base volume remains undisturbed).

Restoring a snapshot image to the base volume, which allows you to roll back the
base volume to a previous point-in-time.
NOTE
The host has immediate access to the newly rolled-back base volume, but the
existing base volume does not allow the host
read-write
access after the rollback
is initiated. You can create a snapshot of the base volume just before initiating the
rollback to preserve the pre-rollback base volume for recovery purposes.