PowerVC Support for Hitachi Global Active Device

This blog describes the prerequisites and setup instructions before using PowerVC to provision Hitachi Global-Active Device (GAD) volumes. Based on how GAD environment is setup in the storage backend, you configure and reserve resources for successful GAD volume provision. 

What is Global-active device (GAD)? 

GAD provides you to the ability to create and maintain synchronous remote copies of data volumes and provides these benefits.

• Continuous server I/O when a failure prevents access to a data volume
• Server failover and failback without storage impact
• Load balancing through migration of virtual storage machines without storage impact

A virtual storage machine is configured with primary and secondary storage systems. When GAD volume is created in the storage backend, it creates a pair of LDEV on both primary and secondary storages. The virtual LDEV number that is assigned may or may not be same. GAD enables data in sync replication, which in turn provides high availability to the running workloads in a disaster.

Storage prerequisites for GAD configuration

GAD licenses must be installed and configured on both primary and secondary storage systems.

PowerVC Storage registration for GAD

Use PowerVC GUI interface to register Hitachi and enable GAD configuration. The table shows the example configuration to explain the GAD workflow. 

Single GAD volume – LDEV and port assignment example

Hitachi Storage GAD setup

Hitachi storage provides you two options to configure GAD between primary storage system and second storage system.

1. Virtual storage machine configured on the secondary storage system only.
2. Virtual storage machine configured on both the primary and secondary storage systems.

Method 1 - Virtual Storage machine configured on only secondary storage system

Virtual storage system is configured only on secondary storage system and the default virtual storage system is used for GAD volume creation. Therefore, before provisioning GAD volumes, you need to reserve the LDEVs, ports, and host groups to the virtual storage system.

Logical view of the configuration.

Follow these steps on the secondary storage before GAD volume creation from PowerVC

As the virtual storage system is configured on secondary storage, all preconfigurations need to be performed only on secondary storage before GAD volume creation from PowerVC. 

1. Reserve the required LDEV or LDEV -range to virtual storage machine on secondary storage system. This LDEV -range is the range

           specified in PowerVC during enable GAD registration. 

1. 1. raidcom unmap resource -ldev_id 2201 -virtual_ldev_id 2201 -I222
   2. raidcom add resource -resource_name GAD_111111 -ldev_id 2201 -I222
   3. raidcom map resource -ldev_id 2201 -virtual_ldev_id reserve -I222

Note

I222 – horcm configuration for secondary storage

2201 – Ldev id on secondary storage

GAD_111111 – resource group name on secondary storage

           2.  Assign the port to the virtual storage machine on secondary storage system. These should be the ports specified in the PowerVC     

                 Storage template. 

1. 1. raidcom add resource -resource_name GAD_111111 -port CL2-C -I222
   2. raidcom add resource -resource_name GAD_111111 -port CL2-D -I222

Note

I222 – horcm configuration for secondary storage

CL2-C, CL2-D – ports on secondary storage

GAD_111111 – resource group name on secondary storage 

            3.  Assign all the host group on a specific port to the virtual storage machine on secondary storage system.

1. 1. raidcom add resource -resource_name GAD_111111 -port CL2-C-x -I222
   2. raidcom add resource -resource_name GAD_111111 -port CL2-D-x -I222

Note

I222 – horcm configuration for secondary storage

CL2-C-x, CL2-D-x– hostgroup on secondary storage, ‘x’ is value from 0-128

GAD_111111 – resource group name on secondary storage

Method 2 - Virtual Storage machine that is configured on both primary and secondary storage system

Virtual storage system is configured on both primary and secondary storage system and is used for GAD volume creation.

Logical view of this configuration. 

Follow these steps before GAD volume creation from PowerVC

Both primary and secondary storage are configured with the virtual storage system and specific preconfigurations need to be performed before GAD volume creation from PowerVC.

Perform these actions in the primary storage

1. Map the required LDEV or LDEV-range to virtual storage machine on primary storage system. This LDEV-range is the value that is

           specified in PowerVC during Hitachi registration for the range of ldev-ids that must be used.

1. 1. raidcom unmap resource -ldev_id 1201 -virtual_ldev_id 1201 -I111
   2. raidcom add resource -resource_name GAD_555555 -ldev_id 1201 -I111
   3. raidcom map resource -ldev_id 1201 -virtual_ldev_id 1201 -I111

Note

I111 – horcm configuration for primary storage

1201 – Ldev id on primary storage

GAD_555555 – resource group name on primary storage

2. Add the port to the virtual storage machine on the primary storage system. Use the port numbers that are specified in the PowerVC 

     primary storage template.

1. 1. raidcom add resource -resource_name GAD_555555 -port CL1-A -I111
   2. raidcom add resource -resource_name GAD_555555 -port CL1-B -I111

Note

I111 – horcm configuration for primary storage

CL1-A, CL1-B – ports on primary storage

GAD_555555 – resource group name on primary storage

3. Add all the host groups on the specific port to the virtual storage machine on primary storage system.

1. 1. raidcom add resource -resource_name GAD_555555 -port CL1-A-x -I222
   2. raidcom add resource -resource_name GAD_555555 -port CL1-B-x  -I222
      

Note

I111 – horcm configuration for primary storage

CL1-A-x, CL1-B-x– hostgroup on primary storage, ‘x’ is value from 0-128

GAD_555555 – resource group name on primary storage

Perform these actions in the secondary storage

1. Reserve the required LDEV or LDEV-range to the virtual storage machine on the secondary storage system.

1. 1. raidcom unmap resource -ldev_id 2201 -virtual_ldev_id 2201 -I222
   2. raidcom add resource -resource_name GAD_555555 -ldev_id 2201 -I222
   3. raidcom map resource -ldev_id 2201 -virtual_ldev_id reserve -I222

Note

I222 – horcm configuration for secondary storage

2201 – Ldev id on secondary storage

GAD_555555 – resource group name on secondary storage 

2. Add the port to the virtual storage machine on the secondary storage system.

1. 1. raidcom add resource -resource_name GAD_555555 -port CL2-C -I222
   2. raidcom add resource -resource_name GAD_555555 -port CL2-D -I222
      

Note

I222 – horcm configuration for secondary storage

CL2-C, CL2-D – ports on secondary storage

GAD_555555 – resource group name on secondary storage

3. Assign all the host groups on the specific port to the virtual storage machine on secondary storage system.

1. 1. raidcom add resource -resource_name GAD_555555 -port CL2-C-x -I222
   2. raidcom add resource -resource_name GAD_555555 -port CL2-D-x  -I222

Note

I222 – horcm configuration for secondary storage

CL2-C-x, CL2-D-x– hostgroup on secondary storage, ‘x’ is value from 0-128

GAD_555555 – resource group name on secondary storage

After completing the preconfigurations, PowerVC is ready to provision volume and virtual machine deployment by using GAD volumes.

Troubleshooting

Volume creation errors occur if the preconfigurations are not performed. Use the error snippet to identify if the setup has the missing configurations.   

If you encounter issues post the preconfigurations, open an IBM Support ticket so we can assist you. 

Happy reading! 😊

Authors

Chhavi Agarwal (chhagarw@in.ibm.com)

Prabhuraj K (k.prabhuraj@in.ibm.com)