Remote Storage Engine

Remote storage is the part of the system that holds the copies of the data. The Remote Storage Engine consists of the media used to store the data, libraries, and drives.

The Remote Storage Engine service runs on computers that are running Windows 2000 Server. Only one Remote Storage Engine can exist on a server. The Remote Storage Engine does not run on Windows 2000 Professional.

Flow Meter Capacity Metric

Remote Storage maintains a flow meter capacity metric monitoring the amount of data that is contained in remote storage, including overflowed and shelved data. Copying data from local storage to remote storage increases the value of the capacity metric. Removing local storage references to data in remote storage decreases the value of the capacity metric. The change in the capacity metric is immediate, but some operations are not immediately detected.

Remote Storage increments the value of the flow meter capacity metric whenever one of the following occurs:

• A new file is managed.
• A previously deleted placeholder is restored to a volume and reconnected to remote storage.

Remote Storage decrements the value of the flow meter capacity metric whenever one of the following occurs:

• A premigrated file is modified.
• A placeholder or premigrated file is deleted.
• A file is unmanaged.

There might be a latency associated with the decrementing of the flow meter capacity metric since the detection of these conditions can happen at a later time.

Storage Pool

All remote storage in Remote Storage exists in a single storage pool: there is no storage pool management required.

Relocation is the movement of data from one remote storage pool to another. Since Remote Storage only supports a single remote storage pool, relocation is not supported in Remote Storage.

Remote Storage supports one storage library within the single tape storage pool. The library must have at least one drive, and two or more drives to support media copies. When multiple drives exist within a library, all drives must be identical in type (for example, density or firmware).

Handling of Physically Full Remote Storage

Remote Storage provides the following options for handling physically full remote storage situations:

• Stop managing new files. Remote Storage becomes a recall-only system; this mode is invoked only after any possible space reclamation is performed.
• Shelf Storage. Remote Storage cycles removable media to "shelf"; recalls of files stored on shelved media require administrator interaction.

Remote storage is considered full either when there is not enough scratch media or when the scratch media are not online. In either case, the administrator must provide manual intervention.

A notice is issued when physical remote storage utilization reaches the administrator-defined warning level.

Shelf Media

Shelf media for Remote Storage are media that are not currently accessible by the system. The medium with the data on it can be removed from the device and the media management subsystem tracks its location. Shelf media allow a system to have more data in remote storage than the device can physically contain.

For removable media, the administrator can remove media and optionally replace them with blank media. Remote Storage continues to premigrate data using the new media, and the removed media are considered shelf media. If a user needs access to data on shelf media, the administrator must place the shelf media in the library, and the new media become shelf media. Media do not need to be full to be shelf media.

Media Status and Location

When a medium is marked as having errors, the administrator is notified of the reason for the status change; the information is also kept in the Windows 2000 Event Log for later reference.

Media within a library are not tied to specific locations or slots. The system adjusts to media being in different locations, so media can be shuffled in a library.

Upgrading Remote Storage Libraries

Removable Storage provides Remote Storage with the ability to replace a library with another library containing identical media and data read/write mechanisms. The administrator must physically move the media from the old library to the new library, that is, physically replace the library, and then use the user interface to register configuration changes within Remote Storage.

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