Wednesday, November 24, 2010

vol copy

This is effectively the same as a vol clone, but you need to do the entire operation before the volume is online and available. You need to create the destination volume first and then restrict it so that it is ready for the copy. Then you start the copy process.

# vol copy start -s snap_name source_vol dest_vol

“-s snap_name” defines the snapshot you want to base the copy on, and “source_vol” and “dest_vol” define the source and destination for the copy. “-S” can also be used to copy across all the snapshots that are also included in the volume. This can be very useful if you need to copy all backups within a volume as well as just the volume data.

# vol copy start [ -S | -s snapshot ] source destination

Copies all data, including snapshots, from one volume to another. If the -S flag is used, the command copies all snapshots in the source volume to the destination volume. To specify a particular snapshot to copy, use the -s flag followed by the name of the snapshot. If neither the -S nor -s flag is used in the command, the filer automatically creates a distinctively-named snapshot at the time the vol copy start command is executed and copies only that snapshot to the destination volume.

The source and destination volumes must either both be traditional volumes or both be flexible volumes. The vol copy command will abort if an attempt is made to copy between different volume types.

The source and destination volumes can be on the same filer or on different filers. If the source or destination volume is on a filer other than the one on which the vol copy start command was entered, specify the volume name in the filer_name:volume_name format.

The filers involved in a volume copy must meet the following requirements for the vol copy start command to be completed successfully:

The source volume must be online and the destination volume must be offline.

If data is copied between two filers, each filer must be defined as a trusted host of the other filer. That is, the filer’s name must be in the /etc/hosts.equiv file of the other filer. If one filer is not in the /etc/hosts.equiv file of the other filer then "Permission denied" error message is displayed to the user.

If data is copied on the same filer, localhost must be included in the filer’s /etc/hosts.equiv file. Also, the loopback address must be in the filer’s /etc/hosts file. Otherwise, the filer cannot send packets to itself through the loopback address when trying to copy data.

The usable disk space of the destination volume must be greater than or equal to the usable disk space of the source volume. Use the df pathname command to see the amount of usable disk space of a particular volume.

Each vol copy start command generates two volume copy operations: one for reading data from the source volume and one for writing data to the destination volume. Each filer supports up to four simultaneous volume copy operations.

# vol copy status [ operation_number]

Displays the progress of one or all active volume copy operations, if any. The operations are numbered from 0 through 3. If no operation_number is specified, then status for all active vol copy operations is provided.

# vol copy throttle [ operation_number ] value

This command controls the performance of the volume copy operation. The value ranges from 10 (full speed) to 1 (one-tenth of full speed). The default value is maintained in the filer’s vol.copy.throttle option and is set 10 (full speed) at the factory. The performance value can be applied to an operation specified by the operation_number parameter. If an operation number is not specified, the command applies to all active volume copy operations.

Use this command to limit the speed of volume copy operations if they are suspected to be causing performance problems on a filer. In particular, the throttle is designed to help limit the volume copy’s CPU usage. It cannot be used to fine-tune network bandwidth consumption patterns.

The vol copy throttle command only enables the speed of a volume copy operation that is in progress to be set. To set the default volume copy speed to be used by future volume copy operations, use the options command to set the vol.copy.throttle option.

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