Setting Up Device Groups

EMC Symmetrix Remote Data Facility devices are configured in pairs. The mirroring relationship between the pairs becomes operational as soon as the EMC Symmetrix Remote Data Facility links are online. If you enable a two-way mirror disks with dynamic EMC Symmetrix Remote Data Facility functionality, you can set up the pair of devices at any time.

The EMC Symmetrix global memory stores information about the pair state of operating EMC Symmetrix Remote Data Facility devices.

Sun Cluster device groups are the entities that you can create and use to manage and control EMC Symmetrix Remote Data Facility pairs. The SYMCLI database file of the host stores information about the device group and the devices that are contained by the group.

The EMC Symmetrix Remote Data Facility device group can hold one of two types of devices:

• RDF1 source device, which acts as the primary

• RDF2 target device, which acts as the secondary

As a result, you can create two types of EMC Symmetrix Remote Data Facility device group, RDF1 and RDF2. An EMC Symmetrix Remote Data Facility device can be moved to another device group only if the source and destination groups are of the same group type.

You can create RDF1 device groups on a host attached to the EMC Symmetrix software that contains the RDF1 devices. You can create RDF2 device groups on a host attached to the EMC Symmetrix software that contains the RDF2 devices. You can perform the same EMC Symmetrix Remote Data Facility operations from the primary or secondary cluster, using the device group that was built on that side.

When you add remote data facility devices to a device group, all of the devices must adhere to the following restrictions:

• The device must be an EMC Symmetrix Remote Data Facility device.

• The device must be either an RDF1 or RDF2 type device, as specified by the device group type.

• The device must belong to the same EMC Symmetrix Remote Data Facility group number.

• The EMC Symmetrix Remote Data Facility device group configuration must be the same on all nodes of both the primary and secondary clusters. For example, if you have a device group DG1, which is configured as RDF1, on node1 of clusterA, then node2 of clusterA should also have a device group called DG1 with the same disk set. Also, clusterB should have an EMC Symmetrix Remote Data Facility device group called DG1, which is configured as RDF2, defined on all nodes.

Checking the Configuration of EMC Symmetrix Remote Data Facility Devices

Before adding EMC Symmetrix Remote Data Facility devices to a device group, use the symrdf list command to list the EMC Symmetrix Remote Data Facility devices configured on the EMC Symmetrix units attached to your host.

# symrdf list

By default, the command displays devices by their EMC Symmetrix device name, a hexadecimal number that the EMC Symmetrix software assigns to each physical device. To display devices by their physical host name, use the pd argument with the symrdf command.

# symrdf list pd

Creating a RDF1 Device Group

The following steps create a device group of type RDF1 and add an RDF1 EMC Symmetrix device to the group.

1. Create a device group named devgroup1.

   phys-paris-1# symdg create devgroup1 -type rdf1

2. Add an RDF1 device, with the EMC Symmetrix device name of 085, to the device group on the EMC Symmetrix storage unit identified by the number 000000003264.

   A default logical name of the form DEV001 is assigned to the RDF1 device.

   phys-paris-1# symld -g devgroup1 -sid 3264 add dev 085