SAN Volume Controller system and Storwize system

Beginning with VM Recovery Manager DR version 1.1 Service Pack 1, the VM Recovery Manager DR solution supports the IBM® SAN Volume Controller (SVC) storage system and IBM Storwize® storage system. Both SVC system and Storwize storage systems follow the same host programming model for mirror management. Hence, the VM Recovery Manager DR solution supports both these storage subsystems by using the same configuration and management interfaces.

The SAN Volume Controller storage system integrates hardware and software components to control the mapping of storage data into volumes in a SAN environment. The SVC storage system includes the rack-mounted hardware components called nodes. Nodes are always installed in pairs. Each node pair is called an I/O group. A single node pair handles the I/O requests on a specific volume. A clustered system contains 1 - 4 I/O groups. A clustered system can have a maximum of eight nodes. When you set up the SVC system across multiple sites, the configuration is called stretched system. When you configure Metro Mirror or Global Mirror mode for data replication across sites, each site must have a separate SVC cluster.

A storage array consists of various physical drives that are logically grouped into Redundant Arrays of Independent Disks (RAID). Each storage system manages a set of logical unit numbers (LUNs) that correspond to storage arrays. The LUNs are mapped to the SVC system as groups of managed disks, which are assigned to a pool of virtual storage. The I/O groups convert the managed disks into storage pools, and then the storage pools are converted into one or more volumes. The volumes are assigned to hosts.

Starting with VM Recovery Manager Version 1.8.0.1, the policy-based replication feature is supported exclusively with Storwize/FlashSystem storage. The required firmware level for the storage is mandatory to enable policy-based replication support with VM Recovery Manager. During the discovery process, if the target storage does not create a host, KSYS will automatically create one using the same WWPN. If a host with the same WWPN already exists, KSYS will use that host for policy-based replication. If a target disk with the same name is already on the target storage, KSYS will create a new disk with a prefixed name, which will then be used for volume group creation. For DR Rehearsal, the user must manually create FC mappings using the target disk created by the policy-based replication volume group. In a policy-based replication environment, after performing operations such as removing the KSYS cluster or modifying HostGroups or WorkGroups, the system does not automatically remove Flash Copy Mappings (FC Mapping) from the Consistency Group or Storwize storage system.

For more information about installation of the SVC system and Storwize system components, see the documentation from the storage vendor.

The VM Recovery Manager DR solution manages disaster recovery across sites by grouping all the disks in a site and establishing a consistency group for the disks in the SVC or Storwize storage systems. During the discovery phase, the KSYS subsystem interacts with the HMC and the VIOS to fetch the storage disk information that is used by the virtual machines. The KSYS then creates a consistency group for each site and enables data consistency across the sites. The KSYS subsystem uses this consistency group to change the replication direction during a planned recovery operation. The KSYS subsystem also checks whether the disks on the storage subsystem are part of any existing consistency groups. If the disk is part of any existing consistency group, the discovery operation fails. In this case, you must ensure that the storage disks are not part of any consistency groups and then run the discovery operation again.

The KSYS subsystem uses a Secure Shell (SSH) application to communicate to the SVC or Storwize command-line interface (CLI). You must configure this connection such that the authentication is established without entering the password so that the KSYS subsystem can communicate to the SVC or Storwize storage system without any intervention.

In the VM Recovery Manager DR solution, the storage agents, which are added to the KSYS configuration, interact with the corresponding storage devices in each site. The following figure shows the storage agent configuration for the SVC storage in the VM Recovery Manager DR solution.