Copying volumes

Command to use to copy volumes

You use the vol copy start command to generate volume copy operations, which produce screen messages that show the progress of the operations.

Each vol copy start command generates two volume copy operations, each of which is assigned a number:

One operation is for reading data from the source volume. Screen messages displayed by a vol copy command refer to this operation as the volcopy dump operation.
One operation is for writing data to the destination volume. Screen messages displayed by a vol copy command refer to this operation as the volcopy restore operation.

When to use the volume copy operation number

You need the volume copy operation number if you want to stop a volume copy operation or change the volume copy operation speed.

For information about obtaining the volume copy operation number, see Checking the status of a volume copy operation.

Number of vol copy operations supported

Whether Data ONTAP can execute a vol copy start command depends on how many volume copy operations are already in progress on the storage systems specified in the vol copy start command, as illustrated in the following examples.

Example

To copy volumes locally, you can enter the following two vol copy start commands on a storage system, which supports four simultaneous copy operations:

vol copy start vol0 vol1

vol copy start vol2 vol3

When these commands are in progress, if you enter additional vol copy start commands, they will fail, because four volume copy operations are already running on the system. Two of the operations are for reading the vol0 and vol2 volumes, and two of the operations are for writing the vol1 and vol3 volumes.

Example

Suppose you enter the following three vol copy start commands on a storage system named systemA to copy volumes to another storage system named systemB:

vol copy start vol0 systemB:vol0

vol copy start vol1 systemB:vol1

vol copy start vol2 systemB:vol2

When these commands are in progress, systemA runs three volume copy operations to read the volumes, and systemB runs three volume copy operations to write the volumes.

An additional vol copy start command to copy between systemA and systemB will succeed because the command adds one more volume copy operation to each storage system.

However, if you enter an additional vol copy start command to copy volumes locally on either systemA or systemB, it will fail. This is because the additional command creates two volume copy operations, one for reading and one for writing, on the storage system that performs the local copying.

Copying Snapshot copies with the vol copy start command

The following table describes the Snapshot copies that will be copied from the source volume and the resulting Snapshot copies on the destination volume, depending on the option you use with the vol copy start command.

Option	Snapshot copies to copy from the source volume	Snapshot copies in the Snapshot file system of the destination volume
None	No Snapshot copies are copied. Only the snap-shot taken after you enter the `vol copy start` command, are copied.	A Snapshot copy named snapshot_for_volcopy.n is created, where n is a number starting at 0 and incrementing by one whole number with each `vol copy` operation is created.
`-S`	All Snapshot copies in the Snapshot file system of the source volume, and the Snapshot copy taken after you enter the `vol copy start command,` are copied.	All Snapshot copy copies in the source volume, and snapshot_for_volcopy.n, where n is a number starting at 0 and incrementing by one whole number with each vol copy operation, are created.
`-s` followed by the name of the Snapshot copy	The specified Snapshot copy will be copied.	The specified Snapshot copy is created.

Note
The vol copy start -S command does not copy any Snapshot copies that are created while the copying is in progress. For example, if the copying lasts from 11:45 p.m. to 1:00 a.m. the next day and Data ONTAP creates a Snapshot copy named nightly.0 at midnight, Data ONTAP does not copy the nightly.0 Snapshot copy.

Copying one volume to another

To copy one volume to another, complete the following step.

Step	Action
1	Enter the following command: vol copy start [-S \| -s snapshot_name] source_volume dest_volume The `-S` and `-s` arguments specify the Snapshot copies to copy. source_volume and dest_volume are the names of the source and destination volumes. If a volume is on a different system, precede the volume name with the system name and a colon. For examples illustrating how to specify volume names, see Examples of the vol copy start command in the following table. Note If the copying takes place between two storage systems, you can enter the `vol copy start` command on either the source or destination system. You cannot, however, enter the command on a third system that does not contain the source or destination volume.

Step

Action

Enter the following command:

vol copy start [-S | -s snapshot_name] source_volume 
dest_volume

The -S and -s arguments specify the Snapshot copies to copy.

source_volume and dest_volume are the names of the source and destination volumes. If a volume is on a different system, precede the volume name with the system name and a colon. For examples illustrating how to specify volume names, see Examples of the vol copy start command in the following table.

Note
If the copying takes place between two storage systems, you can enter the vol copy start command on either the source or destination system. You cannot, however, enter the command on a third system that does not contain the source or destination volume.

Examples of the vol copy start command

The following table shows several examples of the vol copy start command.

If you want to...	Use...
Copy all Snapshot copies from the vol0 volume to the vol1 volume on the same storage system	vol copy start -S vol0 vol1
Copy a nightly Snapshot copy from the vol0 volume to the vol1 volume on the same storage system	vol copy start -s nightly.1 vol0 vol1
Create a Snapshot copy in the vol0 volume to be copied to the vol1 volume on the same storage system	vol copy start vol0 vol1
Copy all Snapshot copies from the vol0 volume to the vol1 volume on a different storage system named systemA	vol copy start -S vol0 systemA:vol1

Error messages generated by vol copy start commands

If your storage system does not meet the requirements for copying a volume, the vol copy start command generates one or more error messages. The following table explains the possible error messages and their meanings.

Error message	Meaning
Permission denied. VOLCOPY: Could not connect to system systemB	The source system does not have permission to copy to the destination system. Action Make sure that the storage systems have a trust relationship with each other.
VOLCOPY: volcopy restore: volume is online, aborting	The destination volume is online. Action Take the destination volume offline.
VOLCOPY: volcopy restore: volume is too small, aborting	The destination volume is smaller than the source volume. Action Add more disk space to the destination volume or choose another destination volume of sufficient capacity.
write: setting up STDERR broken pipe	A local volume copy tried to start, but Remote Shell access is not enabled on the system. Action Enable Remote Shell access on the storage system so that it can receive `rsh` commands.