Discovering storage

Storage nodes in BMC Helix Discovery represent a storage entity on the network on which servers can store data. The term storage entity refers to the physical and logical collection of chassis, devices, disks, processors, embedded OS, and software that make up storage.

A storage entity is typically a rack-mounted device with a large number of disks. Storage entities offer large capacities and redundancy using RAID. Connectivity to the network is usually through a number of ports. Hosts connect to the storage entity through a Storage Area Network (SAN), which may be Fibre Channel (FC) using fiber optics or IP based. A SAN provides block-based storage that appears to the client as a disk. Some other storage entities offer similar capabilities using Network Attached Storage (NAS), which is file-based storage and appears to the client as a file server.

How to discover storage?

BMC Helix Discovery performs discovery of storage entities using the following main approaches:

Discovery using management software

Many storage entities are managed using bespoke storage management software. For example, the Hitachi Virtual Storage Platform is managed using Hitachi HiCommand Server. During routine discovery, if storage management software is discovered, an SI representing the software is created. The creation or confirmation of an SI representing storage management software triggers the appropriate storage discovery pattern. The storage discovery pattern interrogates the management software using WBEM credentials and queries to discover any storage entities that it is managing.

When the pattern discovers the managed storage entity it creates a Storage System node to represent it, and other nodes to represent the associated storage components.

Direct discovery through an embedded provider

Some storage entities that are managed by storage management software can also be discovered directly, bypassing the management software. This is possible if the storage chassis runs an embedded WBEM/SMI-S provider in the chassis. During routine discovery, if a WBEM/SMI-S provider in the storage chassis is discovered, a Storage Device node representing the chassis is created. The creation or confirmation of the Storage Device node triggers the appropriate storage discovery pattern. The storage discovery pattern interrogates the WBEM/SMI-S provider using WBEM credentials and queries to discover the associated storage components.

When attempting to discover a storage entity using a WBEM/SMI-S provider, ensure that WBEM is enabled. (In some systems, it is disabled by default.)

When the pattern discovers the storage entity, it creates a Storage System node to represent it, and other nodes to represent the associated storage components.

Direct discovery using SNMP

Some other storage entities, such as the NetApp products, can be discovered directly using SNMP. In this case, when an SNMP discovery of an IP address finds a storage entity, a Storage Device node representing the chassis is created. The creation or confirmation of the Storage Device node triggers the appropriate storage discovery pattern. The storage discovery pattern continues discovery of the storage entity using further SNMP requests to discover the associated storage components.

When the pattern discovers the storage entity, it creates a Storage System node to represent it, and other nodes to represent the associated storage components.

Discovery using SSH

Some storage entities, such as EMC Isilon Storage Systems, are discovered using SSH. The appropriate storage pattern is triggered on each host running an Isilon ONeFS operating system. The Isilon commands (both cluster specific and node specific) are executed on each host to retrieve the cluster and node details. Then, each cluster and node is modeled in BMC Discovery. The storage discovery pattern continues discovery of the storage entity using further SSH requests to discover the associated storage components. For more information, see EMC Isilon Storage Systems (via SSH).  

What is a Storage Device node?

For storage entities discovered using any of these approaches, the main model consists of a central Storage System node, and associated Storage pools, Storage volumes, Storage processors, Front end FC ports, and Storage connections.

Directly discovered storage entities also have a Storage Device node. The Storage Device node can be regarded in much the same way as the SI representing the storage management software. They are the trigger for the discovery of the storage entity, rather than an integral component.

Requirements for full discovery

The requirements for full discovery of a storage system, and the relationships between them, are as follows:

  • To discover storage using management software:

  • To discover storage directly using the WBEM/SMI-S provider:
  • To discover NetApp storage using SNMP:
    • SNMP credentials valid for the storage device.
    • BMC Helix Discovery must be on a network that can access the NetApp management ports.

      Note

      IPv6 is not supported in the NetApp MIB, so IPv6 virtual interfaces are not discovered.

  • To discover storage using SSH:
  • To discover and link storage consumers:
    • Credentials for accessing any host that is a consumer of the storage.
    • For hosts to be linked to storage, the HBA ID must be discovered.

Discovering the same storage entity using different discovery techniques

It is possible to discover the same storage entity using management software or directly using an embedded WBEM/SMI-S provider. Where this occurs, there might be some differences between the attributes retrieved. For example, it has been observed that the model of some disk drives is missing a suffix when discovered directly, so "STE45085 CLAR450" when scanned using the management system is reported as "STE45085" when scanned directly.

Be aware that if you do discover using both techniques, you will observe some flip-flop in the attributes in the discovered storage components.

Relationships between storage and consumers

The relationships between storage components and consumers of storage is independent of the order of discovery. For example, where hosts have already been discovered, they are linked to Storage connections through their World Wide Port Name (WWPN).

Viewing discovered storage systems

For examples of discovered storage systems and the way they are represented in BMC Helix Discovery, see Viewing a storage system.


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