vxdco

NAME

vxdco - perform operations on DCO objects and DCO volumes

SYNOPSIS

vxdco [-g diskgroup] att volume dco
vxdco [-g diskgroup] attlogvol dco dco_volume
vxdco [-g diskgroup] [-o rm] dis dco
vxdco [-g diskgroup] [-o rm] dislogvol dco
vxdco [-g diskgroup] -o force enable dco

DESCRIPTION

Note The vxdco command can only be used with version 0 DCOs and DCO volumes. It cannot be used with version 20 DCOs and DCO volumes.

The vxdco command is used to manipulate version 0 data change objects (DCO objects or DCOs) and DCO volumes that allow the use of Persistent FastResync with volumes.

The att operation attaches a DCO object, dco, to a volume, volume. If the DCO object has an associated DCO volume, you can use the command vxvol set fmr=on volume to enable Persistent FastResync on the volume after the att operation has completed.

The attlogvol operation associates a DCO volume, dco_volume, with a DCO object, dco. If the DCO object is already attached to a volume, you can use the command vxvol set fmr=on volume to enable Persistent FastResync on the volume after the attlogvol operation has completed.

The dis operation dissociates a DCO object, dco, from a volume, and disables FastResync on that volume. If the -o rm option is specified, the DCO object, the DCO volume, its plexes and associated subdisks are removed in the same operation.

The dislogvol operation dissociates a DCO volume from a DCO object, dco, and disables FastResync on the parent volume. If the -o rm option is specified, the DCO volume, its plexes and associated subdisks are removed in the same operation.

If an error occurs while reading or writing a DCO volume, it is detached and the badlog flag is set on the DCO. (You can use one of the options -a, -F or -m to vxprint to check if the badlog flag is set on a DCO.) The -o force enable operation clears the badlog flag on the DCO.

The following command sequence demonstrates how to recover the DCO volume that tracks the top-level volume vol1 in the disk group egdg:

vxdco -g egdg -o force enable vol1_dco
vxvol -g egdg stop vol1
vxvol -g egdg start vol1

Here vol1_dco is the DCO associated with vol1.

Caution: Only use the -o force enable operation if you are certain that no writes have gone to the volume since the error occurred that caused its DCO volume to become detached. Otherwise, data corruption may result.

The -g diskgroup option specifies the disk group to which the parent volume, DCO object, and DCO volume belong.

You can use the make keyword to vxassist to create a volume with an attached DCO object and DCO volume. You can also use the addlog keyword to vxassist to create and add a DCO object and DCO volume to an existing volume. vxdco may then be used to dissociate a DCO object from its parent volume, and subsequently reattach it if the DCO object and DCO volume have not been removed.

The vxdco command is also used by vxassist and vxplex to handle the DCO objects and DCO volumes that are associated with volumes. The vxmake command is used to create DCO objects, which can be specified using output from vxprint.

Note When using disk group move, split and join (see vxdg(1M)) to move volumes or snapshot volumes between disk groups, take care to ensure that the DCO volumes accompany their parent volumes.

EXIT CODES

The vxdco utility exits with a non-zero status if the attempted operation fails. A non-zero exit code is not a complete indicator of the problems encountered, but rather denotes the first condition that prevented further execution of the utility.

See vxintro(1M) for a list of standard exit codes.

NOTES

When a volume is attached to a DCO as its log volume, its device nodes are deleted. If vxdco dislogvol is subsequently used to dissociate the log volume from the DCO, the device nodes are not recreated.