Snapshot Commands
Snapshot commands are used to control and manage snapshot sets. Snapshot commands can be performed using the Snapshot Utility in SANcentral Tools, or a Command Line Interface (CLI). Before performing any of the Snapshot commands, snapshot sets must be configured on the storage server and a volume must be mapped to the application server and ready for use.
The table below separates all Snapshot commands into three categories: Snapshot Utility Commands, CLI Commands and CLI Group Commands. Most Snapshot commands perform the same function, with the only distinctions being:
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whether the command is performed on a set or group
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whether the command is performed through the Snapshot Utility or command line
The command categories in the following table are as follows:
Snapshot Utility Commands column – lists commands performed from the Snapshot Utility. Commands performed through the Snapshot Utility can be performed on a snapshot set or group, depending on whether you select a set or group in the utility. Refer to Snapshot Utility for more information.
CLI Commands column – lists commands performed on a single snapshot set through a command line. You can use CLI commands for building scripts (or batch jobs) to perform Snapshot activities.
CLI Group Commands column – lists commands performed on snapshot groups through a command line.
CAUTION: When performing CLI commands, run the command window in Run as Administrator mode.
The following is an example of a Snapshot CLI command:
EnableSnap DcsSnap#
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EnableSnap describes the action that the particular CLI command performs.
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DcsSnap# is the argument that identifies a snapshot relationship. When using this command, replace # with the actual snapshot relationship number.
Any I/O errors that occur on an enabled snapshot set may cause the set to have an Unusable status, which will be displayed in the Status column in the Snapshot Utility.
In the table below, refer to Snapshot Utility for instructions on performing any of the commands in that column. For all other commands, refer to the associated topics for details and syntax.
|
Command |
Snapshot Utility Commands |
CLI Commands |
CLI Group Commands |
|
Complete Image (CI) |
Copies any data from the source virtual volume that is not already on the destination virtual volume. CI provides a physical copy, that is independent of the source, for the image point in time of the Enable or Image Update command. | ||
|
Start CI | |||
|
Disable |
Disables an existing snapshot set. Prohibits any snapshot commands from being performed on the set until it is enabled. The state of the destination virtual volume will be undefined unless an established Complete Image (CI) exists for this virtual volume. | ||
|
Disable | |||
|
Enable |
Creates a logical image of the source virtual volume on the destination at a specific point in time. The image is instantly available for use, and is independent of the source virtual volume from which it was created. After a snapshot is enabled, additional commands can be performed on it. Note: Once enabled, both the source and the destination may be accessed (Read/Write) at any time. When the destination is accessed, its contents will reflect the data of the source at the particular point in time that the set was enabled, even though the content of the source may have changed. | ||
|
Enable | |||
|
Extended Status |
Retrieves the status of the various Snapshot processes, including the percentage of the data difference between the source and destination virtual volumes, the percentage of destination virtual volume completion, and whether a set is currently enabled or disabled. | ||
|
Free NMV Blocks |
Frees NMV storage units allocated to a Snapshot destination virtual volume from an NMV. This command can only be used after disabling, and before re-enabling the snapshot set. This function has no effect on a destination virtual volume created from a partition-based volume. | ||
|
Discard SAU | |||
|
Image Update |
Updates the logical image on the destination virtual volume with the latest changes to the source virtual volume and updates the point in time. If an Image Update is performed on a snapshot relationship with a previously performed Complete Image, the CI will be invalid and must be performed again to re-establish the Complete image. (This CI will be completed faster since only the data changed on the source since the last enable or image update was performed on the snapshot relationship will be copied.) | ||
|
Start IU | |||
|
Last Error |
Retrieves information pertaining to the last Snapshot operation error. | ||
|
|
| ||
|
Status |
Retrieves the status of the various Snapshot processes for a set, including whether a set is currently enabled or disabled. | ||
|
| |||
|
Source Update |
Resynchronizes the snapshot source and destination virtual volumes so that the source virtual volume will become a copy of the current state of the destination virtual volume and the updates the image point in time. | ||
|
Start SU |
| ||
|
CI Delays |
Sets a millisecond delay for the transfer of data associated with the Complete Image process. | ||
|
Set Delays |
| ||
|
Stop CI |
Stops the Complete Image Process on a particular snapshot set. | ||
|
Stop CI |
| ||
|
Stop IU |
Stops the Image Update Process on a particular snapshot set. | ||
|
Stop IU |
| ||
|
Stop SU |
Stops the Source Update Process on a particular snapshot set. | ||
|
Stop SU | |||
|
Delays | |||
|
CI Delays |
Sets a millisecond delay for the transfer of data associated with the Complete Image process. | ||
|
Set Delays | |||
|
SU Delays |
Sets a millisecond delay for the transfer of data associated with the Source Update process. | ||
|
Set Delays | |||
Additional Command Notes:
*EnableNewSnap and GroupEnableNew have been phased out. EnableNewSnap has the same function as EnableSnap and is only maintained for backward compatibility. GroupEnableNew has the same function as GroupEnable and is only maintained for backward compatibility.
GroupGetConfig is no longer supported and no longer documented. This command is only provided in the installation files for backward compatibility.
All SCSI Group Commands have been phased out. Remote administration of Snapshot must be done using DataCore VSS.