startrcconsistgrp

The startrcconsistgrp command starts the Metro Mirror or Global Mirror consistency group copy process, sets the direction of copy if it is undefined, and optionally marks the secondary VDisks of the consistency group as clean.

Syntax


>>- svctask -- -- startrcconsistgrp -- ------------------------->

>--+--------------------------+-- --+----------+-- ------------->
   '- -primary --+- master -+-'     '- -force -'      
                 '- aux ----'                         

>--+----------+-- --+- rc_consist_group_id ---+----------------><
   '- -clean -'     '- rc_consist_group_name -'

Parameters

-primary master | aux: (Optional) Specifies the copy direction by defining whether the master or auxiliary disk becomes the primary (source). This parameter is required when the primary is undefined if, for example, the consistency group is in the Idling state.
-force: (Optional) Specifies that you want the system to process the copy operation even if it might lead to a temporary loss of consistency while synchronization occurs. This parameter is required if the consistency group is in the ConsistentStopped state, but is not synchronized or is in the Idling state, but is not synchronized.
-clean: (Optional) Specifies that the VDisk that is to become a secondary is clean for each of the relationships belonging to the group; any changes made on the secondary VDisk are ignored, and only changes made on the clean primary VDisk are considered during synchronization of the primary and secondary disks. The consistency group must be in an Idling (connected) state for this parameter to work.
Attention: This flag should only be used when the primary and secondary VDisks contain identical data. Otherwise, relationships that are not consistent are reported as consistent. Once this has been done there is no method to determine whether these VDisks ever reach a true consistent state until a full background copy can be carried out again.
rc_consist_group_id | rc_consist_group_name: (Required) Specifies the ID or name of the consistency group to start.

Description

This command starts a Metro Mirror or Global Mirror stand-alone consistency group.

This command can only be issued to a consistency group that is connected. For a consistency group that is idling, this command assigns a copy direction (primary and secondary roles) and begins the copy process. Otherwise, this command restarts a previous copy process that was stopped either by a stop command or by an I/O error.

If the resumption of the copy process leads to a period of time when the relationship is not consistent, then you must specify the -force parameter when you restart the relationship. This situation can arise if the relationship had been stopped and then further input transactions had been performed on the original primary disk of the relationship. When you use the -force parameter in this situation, the data on the secondary disk is not usable (because it is inconsistent) in a disaster recovery circumstance.

In the idling state, you must provide the -primary parameter. In other connected states, you can provide the -primary parameter, but it must match the existing setting.

The -force parameter is required if consistency would be lost by starting a copy operation. This can occur if write operations on either primary or secondary VDisks have taken place since the ConsistentStopped or idling state occurred. If the command is issued without the -force parameter in such circumstances, the command fails. In general, the -force parameter is required if the group is in one of the following states:

Consistent_Stopped but not synchronized (sync=out_of_sync)
Idling but not synchronized

The -force parameter is not required if the group is in one of the following states:

Inconsistent_Stopped
Inconsistent_Copying
Consistent_Synchronized

However, the command does not fail if you specify the -force parameter.

The -clean parameter is used when a Metro Mirror or Global Mirror group is started and the secondary VDisks in this group are assumed to be clean. Clean in this sense, means that any changes that have been made at the secondary are ignored and only changes made at the primary are considered when synchronizing the primary and secondary VDisks. The -clean parameter can be used in the following scenario:

A consistency group is created with the -sync parameter. At this point, it does not matter if the primary and secondary contain the same data, even though the use of the -sync parameter implies that this is true.
A stoprcconsistgrp command is issued with the -access parameter. This permits access to the secondary disk. Change recording begins at the primary.
An image of the primary disk is copied and loaded on to the secondary disk. It is permissible to allow updates to the primary disk during the image copy as this image can be only a fuzzy image of the primary disk.
A startrcconsistgrp command that specifies the -primary master, -force, and -clean parameters is issued. The auxiliary disk is marked as clean and changes on the master disk that have occurred since the relationship was stopped are copied to the auxiliary disk.
Once the background copy has completed, relationships in the group become consistent and synchronized.

An invocation example

svctask startrcconsistgrp rccopy1

The resulting output

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