Hitachi storage systems

The VM Recovery Manager DR solution supports disaster recovery (DR) for third-party vendor storage from Hitachi. The VM Recovery Manager DR solution supports both synchronous and asynchronous data replication by using Hitachi TrueCopy remote replication and Hitachi Universal Replicator (HUR) technologies.

Notes:
  • VM Recovery Manager DR supports the following models of the Hitachi storage system:
    • Hitachi Virtual Storage Platform (VSP) G200
    • Hitachi VSP G400
    • Hitachi VSP G600
    • Hitachi VSP G800
    • Hitachi VSP G1000
  • VM Recovery Manager DR supports both synchronous and asynchronous modes of storage replication.
The setup of VM Recovery Manager DR disaster recovery for Hitachi mirrored storage system involves the following steps:
  1. Plan the storage deployment and replication necessary for your environment. This process is related to the applications and middleware that must be deployed in the environment that you want to include in the recovery management by the VM Recovery Manager DR solution.
  2. Use the storage configuration tools that are provided by Hitachi to configure the storage devices you have defined in step 1, and deploy the devices. For more details on setting up your environment for Hitachi storage systems, see Setting up VM Recovery Manager DR for Hitachi storage systems
  3. Use the ksysmgr interface to discover the deployed storage devices and to define the disaster recovery policies for the applications or virtual machines that are using the mirrored storage.

Hitachi storage management uses Command Control Interface (CCI) operations from the AIX® operating system and VM Recovery Manager DR environment. The KSYS subsystem uses CCI to discover and integrate the Hitachi storage replication into the disaster recovery framework of VM Recovery Manager DR. This integration manages disaster recovery for applications that use the mirrored storage. In the VM Recovery Manager DR solution, the storage agents, which are added to the KSYS configuration settings, interact with the corresponding CCI software in each site.

Hitachi Command Control Interface (CCI)

The remote and in-system replication software from Hitachi requires the following CCI components to manage the disk pairs:
Command device
The command devices are located in storage systems. CCI uses the command device as the interface to the storage system from the host. The command device accepts commands from the host and executes them on the storage system. The command device is a dedicated logical volume.
Hitachi Open Remote Copy Manager (HORCM)
The HORCM is located in the CCI server. The HORCM operates as a daemon process. When activated, the HORCM refers to CCI configuration definition files that are also located on the CCI server. The HORCM instance communicates with the storage system and remote servers.

HORCM definition files describe the storage systems, pair volumes, and data paths. When you run a command, CCI uses the information in the HORCM files to identify target volumes of the command.

Two HORCM files are required for each pair. One file describes the primary volumes (P-VOLs), and the other file describes the secondary volumes (S-VOLs). The following figure shows an example setup of Hitachi storage configuration with two HORCM instances.

Figure 1. Relationship between storage agents and storage disks
Example of Hitachi storage configuration

Requirements

The VM Recovery Manager DR solution requires the following components for Hitachi storage configuration:
  • Command Control Interface (CCI) software for AIX. For more information about CCI, see Hitachi Command Control Interface (CCI) documentation that is maintained by Hitachi. The CCI software must also be installed on the KSYS LPAR to communicate with the CCI server.
  • The VM Recovery Manager DR solution requires CCI version 01-39-03/04 with model RAID-Manager/AIX.

Limitations

Consider the following limitations when you use the Hitachi storage systems in the VM Recovery Manager DR solution:
  • The device names (dev_name attributes) must map to logical devices and the device groups (dev_group attributes) must be defined under the HORCM_LDEV section in the horcm.conf file.
  • The VM Recovery Manager DR solution uses the dev_group attribute for any basic operation that is related to the Hitachi storage systems. Some examples of basic operations are pairresync, pairevtwait, and horctakeover. If several device names exist in a device group, the device group must be consistency-enabled.
  • For command devices, the Security option in the Command Device Attributes panel must be disabled and the User Authentication option must be enabled. Otherwise, the required information, such as logical device (LDEV) ID, journal volume ID, consistency group ID, and volume type, are not displayed in any command output. The KSYS subsystem needs these information to monitor the state of storage subsystem disks.
  • The HUR technology requires journal groups. Each pair relationship in a journal group is called mirror. A mirror ID is required for the 3-data-center (3DC) configuration. In a 3DC configuration, two or more restore journal groups can be set for one master journal group. The VM Recovery Manager DR supports 2-data-center (2DC) configuration currently that does not require a mirror ID. The VM Recovery Manager DR configuration uses 0 mirror ID for synchronous (TrueCopy) and asynchronous (Universal Copy) configuration.
  • The VM Recovery Manager DR solution does not trap Simple Network Management Protocol (SNMP) notification events for HUR storage. If an HUR link goes down when the hosts are functional and later the HUR link is repaired, you must manually resynchronize the disk pairs.
  • The KSYS subsystem does not control the creation of disk pairs. You must create the disk pairs before you start the KSYS partition.
  • Dynamic manipulation of disk groups is not supported for Hitachi storage systems. The KSYS subsystem might break the grouping of the disks in a disk group during the group manipulation operation. When a disk is removed from a disk group, the disk moves into simplex state.
    The following cases result in disk removal from a disk group. In these cases, the Hitachi storage subsystem removes the pair relationship.
    • Removing disks from a virtual machine
    • Performing Live Partition Mobility operation or Remote Restart operation across host groups
    • Restoring a snapshot
    • Unmanaging a virtual machine from the KSYS subsystem
    • Removing a host from host group and adding the host to another host group
    • Removing a cluster
    You must recreate the disk pair explicitly before you add the same disk or virtual machine to the VM Recovery Manager DR management.
  • Hosts that are managed by the VM Recovery Manager DR solution cannot contain volume groups with both HUR-protected and non-HUR-protected disks. A host must contain an HUR-protected disk.
  • All hosts within a site that are managed by the VM Recovery Manager DR solution must use the same HORCM instance.
  • All disks within a site must belong to the same journal volume.
  • You must not add any special character to the HORCM configuration file. You must use only spaces to segregate all the fields in the HORCM file.