Administering Hitachi TrueCopy Data Replication Device Groups

This section provides the following information about administering Hitachi TrueCopy data replication device groups:

• How to Add a Data Replication Device Group to a Hitachi TrueCopy Protection Group

• Validations Made by the Data Replication Subsystem

• How the State of the Hitachi TrueCopy Device Group is Validated

• How to Modify a Hitachi TrueCopy Data Replication Device Group

• How to Delete a Data Replication Device Group From a Hitachi TrueCopy Protection Group

For details about configuring a Hitachi TrueCopy data replication protection group, see How to Create and Configure a Hitachi TrueCopy Protection Group.

How to Add a Data Replication Device Group to a Hitachi TrueCopy Protection Group

Steps

1. Log in to one of the cluster nodes.

   You must be assigned the Geo Management RBAC rights profile to complete this procedure. For more information about RBAC, see Sun Cluster Geographic Edition Software and RBAC.

2. Create a data replication device group in the protection group.

   This command adds a device group to a protection group on the local cluster and propagates the new configuration to the partner cluster if the partner cluster contains a protection group of the same name.

   # geopg add-device-group -p property-settings [-p...] device-group-name protection-group-name

   -p property-settings

   Sets the properties of the data replication device group

   The Hitachi TrueCopy specific property that you can set is the following:

   • Fence_level – defines the fence level that is used by the device group. The fence level determines the level of consistency among the primary and secondary volumes for that device group.

     This property can take the values of data, status, never, or async. When you use a Fence_level of never or async, the application can continue to write to the primary cluster even after failure on the secondary cluster. However, when you set the Fence_level to data or status, the application on the primary cluster might fail because the secondary cluster is not available for reasons such as:

     • Data replication link failure

     • Secondary cluster and storage is down

     • Storage on the secondary cluster is down

   ---

   Caution –

   To avoid application failure on the primary cluster, specify a Fence_level of never or async. If you have special requirements to use a Fence_level of data or status, consult your Sun representative.

   ---

   For more information about application errors associated with different fence levels, see the Sun StorEdge SE 9900 V Series Command and Control Interface User and Reference Guide.

   The other properties you can set depend upon the type of data replication you are using. For details about these properties, see Appendix A, Standard Sun Cluster Geographic Edition Properties.

   device-group-name

   Specifies the name of the new data replication device group

   protection-group-name

   Specifies the name of the protection group which will contain the new data replication device group

   For information about the names and values that are supported by Sun Cluster Geographic Edition software, see Appendix B, Legal Names and Values of Sun Cluster Geographic Edition Entities.

   For more information about the geopg command, refer to the geopg(1M) man page.

Example 10–11 Adding a Data Replication Device Group to a Hitachi TrueCopy Protection Group

The following example illustrates how to create a Hitachi TrueCopy data replication device group in the tcpg protection group:

# geopg add-device-group -p Fence_level=data devgroup1 tcpg

Validations Made by the Data Replication Subsystem

When the Hitachi TrueCopy device group, configured as dev_group in the /etc/horcm.conf file, is added to a protection group, the data replication layer makes the following validations.

• Validates that the horcmd daemon is running on all of the nodes given in the Nodelist property of the protection group.

  For more information about the horcmd daemon, see the Sun StorEdge SE 9900 V Series Command and Control Interface User and Reference Guide

• Checks that the path to the storage device exists from all of the nodes given in the Nodelist property. The storage device controls the newHitachi TrueCopy device group.

• The Hitachi TrueCopy device group properties specified in the geopg add-device-group command are validated as described in the following table.

When a Hitachi TrueCopy device group is added to a protection group, a Sun Cluster resource is automatically created by this command. This resource monitors data replication. The name of the resource is r-tc-protection-group-name-device-group-name. This resource is placed in the corresponding Sun Cluster resource group, which is named rg-tc-protection-group-name.

You must use caution before you modify these replication resources with Sun Cluster commands. These resources are for internal implementation purposes only.

How the State of the Hitachi TrueCopy Device Group is Validated

For validation purposes, Sun Cluster Geographic Edition gives each Hitachi TrueCopy device group a state according to the current state of its pair. This state is returned by the pairvolchk -g <DG> -ss command.

The remainder of this section describes the individual device group states and how these states are validated against the local role of the protection group.

Determining the State of an Individual Hitachi TrueCopy Device Group

An individual Hitachi TrueCopy device group can be in one of the following states:

• SMPL

• Regular Primary

• Regular Secondary

• Takeover Primary

• Takeover Secondary

The state of a particular device group is determined by using the value returned by the pairvolchk -g <DG> -ss command. The following table describes the device group state associated with the values returned by the pairvolchk command.

Determining the Aggregate Hitachi TrueCopy Device Group State

If a protection group contains only one Hitachi TrueCopy device group, then the aggregate device group state is the same as the individual device group state.

When a protection group contains multiple Hitachi TrueCopy device groups, the aggregate device group state is obtained as described in the following table.

For any other combination of individual device group states, the aggregate device group state cannot be obtainable and is considered a pair-state validation failure.

Validating the Local Role of the Protection Group Against the Aggregate Device Group State

The local role of a Hitachi TrueCopy protection group is validated against the aggregate device group state as described in the following table.

Example 10–12 Validating the Aggregate Device Group State

The following example illustrates how the state of a Hitachi TrueCopy device group is validated against the role of the Hitachi TrueCopy protection group to which it belongs. First, the protection group is created as follows:

phys-paris-1# geopg create -s paris-newyork-ps -o primary -d truecopy tcpg

A device group, devgroup1, is added to the protection group, tcpg, as follows:

phys-paris-1# geopg add-device-group -p fence_level=async devgroup1 tcpg

The current state of a Hitachi TrueCopy device group, devgroup1, is given in the output of the pairdisplay command as follows:

phys-paris-1# pairdisplay -g devgroup1 
Group PairVol(L/R) (Port#,TID,LU),Seq#,LDEV#,P/S,Status,Fence,Seq#,P-LDEV# M 
devgroup1 pair1(L) (CL1-A , 0, 1) 12345   1..P-VOL PAIR ASYNC,54321  609   -
devgroup1 pair1(R) (CL1-C , 0, 20)54321 609..S-VOL PAIR ASYNC,-----   1    - 
devgroup1 pair2(L) (CL1-A , 0, 2) 12345   2..P-VOL PAIR ASYNC,54321  610   - 
devgroup1 pair2(R) (CL1-C , 0,21) 54321 610..S-VOL PAIR ASYNC,-----   2    -

The pairvolchk -g <DG> -ss command is run and returns a value of 23.

phys-paris-1# pairvolchk -g devgroup1 -ss
parivolchk : Volstat is P-VOL.[status = PAIR fence = ASYNC]
phys-paris-1# echo $?
23

The output of the pairvolchk command is 23, which corresponds in Table 10–1 to an individual device group state of Regular Primary. Because the protection group contains only one device group, the aggregate device group state is the same as the individual device group state. The device group state is valid because the local role of the protection group, specified by the -o option, is primary, as specified in Table 10–3.

How to Modify a Hitachi TrueCopy Data Replication Device Group

Steps

1. Log in to one of the cluster nodes.

   You must be assigned the Geo Management RBAC rights profile to complete this procedure. For more information about RBAC, see Sun Cluster Geographic Edition Software and RBAC.

2. Modify the device group.

   This command modifies the properties of a device group in a protection group on the local cluster. Then the command propagates the new configuration to the partner cluster if the partner cluster contains a protection group of the same name.

   # geopg modify-device-group -p property-settings [-p...] \ TC-device-group-name protection-group-name

   -p property-settings

   Sets the properties of the data replication device group

   For more information about the properties you can set, see Appendix A, Standard Sun Cluster Geographic Edition Properties.

   TC-device-group-name

   Specifies the name of the new data replication device group

   protection-group-name

   Specifies the name of the protection group that will contain the new data replication device group

Example 10–13 Modifying the Properties of a Hitachi TrueCopy Data Replication Device Group

The following example illustrates how to modify the properties of a data replication device group that is part of a Hitachi TrueCopy protection group:

# geopg modify-device-group -p fence_level=async tcdg tcpg

How to Delete a Data Replication Device Group From a Hitachi TrueCopy Protection Group

Before You Begin

You might delete a data replication device group from a protection group if you added a data replication device group to a protection group. Normally, after an application is configured to write to a set of disks, you would not change the disks.

Deleting a data replication device group does not stop replication or change the replication status of the data replication device group.

For information about deleting protection groups, refer to How to Delete a Hitachi TrueCopy Protection Group. For information about deleting application resource groups from a protection group, refer to How to Delete an Application Resource Group From a Hitachi TrueCopy Protection Group.

Steps

1. Log in to one of the cluster nodes.

   You must be assigned the Geo Management RBAC rights profile to complete this procedure. For more information about RBAC, see Sun Cluster Geographic Edition Software and RBAC.

2. Remove the device group.

   This command removes a device group from a protection group on the local cluster. Then the command propagates the new configuration to the partner cluster if the partner cluster contains a protection group of the same name.

   # geopg remove-device-group device-group-name protection-group-name

   device-group-name

   Specifies the name of the data replication device group

   protection-group-name

   Specifies the name of the protection group

   When a device group is deleted from a Hitachi TrueCopy protection group, the corresponding Sun Cluster resource, r-tc-protection-group-name-device-group-name, is removed from the replication resource group. As a result, the deleted device group is no longer monitored. The resource group is removed when the protection group is deleted.

Example 10–14 Deleting a Replication Device Group From a Hitachi TrueCopy Protection Group

The following example illustrates how to remove a Hitachi TrueCopy data replication device group:

# geopg remove-device-group tcdg tcpg