Details about copying one volume to another

Command syntax for copying one volume to another

To copy one volume to another, use the following command syntax:

vol copy start [ -S | -s snapshot ] source destination
Specifying the snapshots to copy

The -S and -s arguments specify the snapshots to copy. The following table describes the snapshots to copy and the resulting snapshots on the destination volume, depending on the argument.

Argument used Snapshots to copy from the source volume Snapshots in the snapshot file system of the destination volume
None The snapshot taken after you enter the vol copy start command A snapshot named snapshot_for_backup.n, where n is a number starting at 0
-S All snapshots in the snapshot file system of the source volume and the snapshot taken after you enter the vol copy start command All snapshots in the source volume and snapshot_for_backup.n, where n is a number starting at 0
-s followed by the name of the snapshot The specified snapshot The specified snapshot

Note: The vol copy start -S command does not copy any snapshots that are created when 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 the filer creates a snapshot named nightly.1 at midnight, the filer does not copy the nightly.1 snapshot.


Specifying the volumes involved in the copy

The source and destination arguments are the names of the volumes. If a volume is on a different filer, precede the volume name with the filer name and a colon. For examples illustrating how to specify volume names, see "Examples of the vol copy start command."

Where to enter the vol copy start command

If the copying takes place between two filers, you can enter the command on either the source or destination filer. You cannot, however, enter the command on a third filer 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... Enter...
Copy all snapshots from the vol0 volume to the vol1 volume on the same filer
vol copy start -S vol0 vol1
Copy a nightly snapshot from the vol0 volume to the vol1 volume on the same filer
vol copy start -s nightly.1 vol0 vol1
Create a snapshot in the vol0 volume to be copied to the vol1 volume on the same filer
vol copy start vol0 vol1
Copy all snapshots from the vol0 volume to the vol1 volume on a different filer named filerA
vol copy start -S vol0 filerA:vol1

Results of the vol copy start command

The vol copy start command generates volume copy operations and produces screen messages showing the progress of the operations.

Volume copy operations

Each vol copy start command generates two volume copy operations, as described in the following list:

The filer assigns a volume copy operation number to each 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 more information about obtaining the volume copy operation number, see "Checking the status of a volume copy operation."

Screen messages from the vol copy command

When the filer is copying a volume, the filer displays messages indicating the percentage of the volume copy operation completed and the number of minutes remaining. When the filer finishes copying all data, it displays the filer prompt.

Maximum number of simultaneous volume copy operations

Each filer supports up to four simultaneous volume copy operations. Whether a filer can execute a vol copy start command depends on how many volume copy operations are already in progress on the filer or filers specified in the vol copy start command, as illustrated in the following examples.

Example

You can enter the following two vol copy start commands on a filer to copy volumes locally:

vol copy start vol0 vol1
vol copy start vol2 vol3

When these commands are in progress, you cannot enter additional vol copy start commands because four volume copy operations are already running on the filer. 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 filer named filerA to copy volumes to another filer named filerB.

vol copy start vol0 filerB:vol0
vol copy start vol1 filerB:vol1
vol copy start vol2 filerB:vol2

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

You can enter an additional vol copy start command to copy between filerA and filerB because the command adds one more volume copy operation to each filer.

However, you cannot enter an additional vol copy start command to copy volumes locally on either filerA or filerB. This is because the additional command would create two volume copy operations, one for reading and one for writing, on the filer that performs the local copying. The filer cannot support these two additional volume copy operations because three operations are already in progress.

Possible errors

If your filer does not meet a requirement described in "Requirements and recommendation for copying a volume", the vol copy start command generates one or more error messages. The following table explains the meanings of the possible error messages.

Error message Meaning
Permission denied.

 
VOLCOPY: Could not connect to 
filer 127.0.0.1.
The source filer does not have permission to copy to the destination filer.
Action
Make sure that the filers have a trusting relationship with each other. If both the source volume and destination volume are on the same filer, remember to include localhost in the /etc/hosts.equiv file.
VOLCOPY: volcopy restore: 
volume is online, aborting
The destination volume is on-line.
Action
Take the destination volume off-line and reboot the filer that contains the destination volume.
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.


Copyright © 1999, Network Appliance, Inc. All rights reserved.

Part No. 210-02334
File: volcopy3.htm
Last updated: 04/26/99 08:11:53