Components

The following figure illustrates the major components of SAN File System.

Figure 1. SAN File System components
This figure illustrates how the components of the SAN File System system are connected to the internal IP network and SAN fabric.

The metadata servers and clients communicate over an private IP network and access data over a Fibre Channel storage attached network (SAN). SAN File System relies on networking hardware (including an IP network, SAN, network switches, and routers) that already exists in your environment.

The metadata servers run on separate physical machines (known as engines) and perform metadata, administrative, and storage-management services. The metadata servers are clustered for scalability and availability, and are referred to collectively as the cluster. In the cluster, there is one master metadata server and one or more subordinate metadata servers. Additional metadata servers can be added, as required, when the workload grows.

The metadata resides on private storage that is shared among all the metadata servers in the cluster. This storage is known as the system storage pool. A storage pool is a collection of SAN File System volumes in the SAN. The system storage pool contains the system metadata (such as system configuration and state information) and file metadata (such as file creation date and permissions). The actual file data is stored on the user storage pools, which may be shared among the clients.

The administrative server allows SAN File System to be remotely monitored and controlled through a Web-based user interface, called the SAN File System console. In addition, the administrative server processes requests issued from the administrative command-line interface, which can also be accessed remotely. The ability to access the SAN File System through these two types of interfaces allows you to administer SAN File System from almost any system with network connectivity. The administrative server uses an LDAP server to look up authentication and authorization information about the administrative users. The primary administrative server runs on the same engine as the master metadata server. It receives all requests issued by administrators and also communicates with the administrative servers that run on each additional metadata server in the cluster to perform routine requests.

Computers that are going to share data and have their storage centrally managed are all connected to the SAN. In SAN File System, these computers are known as clients. The SAN File System client software enables the clients to access a single, uniform global namespace through a virtual or installable file system. These clients can act as servers to a broader clientele, providing network File System (NFS) or Common Internet File System (CIFS) access to the global namespace or hosting applications (such as database servers or Web-hosting services that use multiple servers).

The master console provides serviceability features, including the remote-support interface (or remote access) and service alert (for call home) capabilities. The master console is a required feature for SAN File System that can be shared with other IBM® TotalStorage® products, such as SAN Volume Controller.

Parent topic: Concepts

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