Microsoft KB Archive/240856

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Removable Storage Manager Terms and Definitions

Article ID: 240856

Article Last Modified on 3/1/2007


  • Microsoft Windows 2000 Server
  • Microsoft Windows 2000 Advanced Server
  • Microsoft Windows 2000 Professional Edition
  • Microsoft Windows 2000 Datacenter Server

This article was previously published under Q240856


This article describes common terminology used with Removable Storage Manager (RSM).


You can use RSM to manage online libraries (such as changers and jukeboxes) and track removable tapes and disks. RSM facilitates communication between removable-media storage systems and data management programs, such as Windows Backup and Remote Storage Server (RSS). RSM labels, catalogs, and tracks all media, controls the drives, slots, and doors, and provides uniform drive cleaning operations.

The following list describes common RSM terminology. You can also find many of these terms in the Windows Help file.

Allocated - The side is claimed for use by an application and is not available to any other application. A logical media representation of this side exists. Only writable media can be allocated.

Allocation Maximum - A piece of media can be deallocated and reallocated by an application. An application can reallocate a piece of available media that remains in the application media pool until it reaches its reallocation limit, which is determined by an administrator or an application. RSM keeps track of the number of times a side is allocated. When this count crosses a threshold, the side is decommissioned. Sides in this state are past their useful life. This count is checked when a side is deallocated.

Application Media Pool - Each application that uses media managed by RSM uses one or more application pools. Applications create these pools or you can create these pools using a snap-in. You can set permissions on application pools so that applications and users can share pools, or an application can have its own set of dedicated pools.

Auto Configuration - RSM auto-configures a robotic library if all of the following conditions exist:

  • The robotic library hardware unit supports drive element address reporting with the ReadElementStatus SCSI command. Consult the manufacturer of your library hardware unit to find out if this feature is supported.
  • All drives inside the robotic library are on the same SCSI bus as the library itself.

Available Media - Side that is available for claiming. Any application with access to the media pool in which the media is located can use available media.

Bar Code - A bar code is a machine-readable physical label that is attached to physical media. These barcodes are similar to the barcode labels on most packaged goods.

Bar Code Reader - Libraries that hold media with bar codes attached can have a bar code reader. Libraries with bar code readers can scan bar code labels on physical media. You can use this as a shortcut in determining the identity of media sides. Physically mounting and reading an on-media label can be time consuming because it requires reading data on the media. You might have to put the medium on a drive. With unique bar codes, a bar code scan is a much faster way of determining the identity of a physical medium and the sides it contains.

Completed -

  • As a side state: Indicates that a side is in use, but can no longer be used for write operations. The side is physically or logically full.
  • As a work queue item: When RSM completes the request, the work queue item for that request enters the completed state.
  • As an operator request state: Indicates that an administrator or RSM has specified that the action is finished.

Deallocate - An application or an operator can issue a deallocate command to make a piece of media available to other applications.

Deallocated - The side is no longer claimed by an application. After you deallocate a medium, you can leave it in the application media pool, move it to another application pool, or free the pool for reuse. Your application can reallocate a piece of available media that remains in the application media pool until it reaches its allocation maximum, which is determined by an administrator or an application.

Decommissioned - A side state: Indicates a side can no longer be used because it reached its allocation maximum (specified by the administrator or an application).

Dismount - An application or operator can issue a dismount command to move physical media from a drive to a library slot.

Door - You can use a door to gain unconstrained access to the contents of a library. In larger libraries, this is similar to the usual concept of a door (handle, hinges, and so on). When a door is open, you can reach inside the library to add and remove media. Doors in smaller libraries do not look exactly like regular doors, but function in the same way. For example, all of the slots in some small changers are in a magazine. When you "open the door" on the slots, the changer pushes the magazine out through the front of the changer. Then you can add, replace, or remove media and reinsert the magazine into the changer. In either case, when you add media to a library using a door, you place the media directly into a slot. Not all libraries have a door. For related information, refer to the "Port" and "Door Access" terms in this article.

Door Access - You can remove media using a door. If you exchange media in libraries without a bar code during a door access, you must run a full inventory after completing the door access. The change is not detected by a fast inventory and an identity mismatch occurs the next time media in the slot is mounted. For related information, refer to the "Door" term in this article.

Drive - A drive is a device that can read or write data to media. For example, a Jaz drive can read and write Jaz cartridges. A library has at least one drive, but may contain several.

Eject - RSM uses a library's port (if one exists) for inserting and ejecting media, otherwise it uses a door. Libraries with ports can use the Eject wizard to eject media.

Failed - Work item state: If RSM is unable to complete the request, the work queue item for that request enters the failed state.

Free Pool - The primary purpose of the free pool is to support sharing media among applications. The free media pool contains media that are freely available to any application. The free media pool holds no useful data. An application draws media from the free pool when it needs additional media and returns media to the free pool when it is no longer needed so it can used by other applications. When an application draws a piece of media from the free pool, the application can make no assumptions about the contents of the media. There is no useful data and the data may not even be labeled in any recognizable way. For related information, refer to the "Prepare" term in this article.

Globally Unique Identifier (GUID) - GUIDs are assigned to both physical and logical media in the form of a 32-byte string. For example:


Idle - A physical media state: Indicates that the medium is in a library slot (or on a shelf if it is in the offline physical location).

Imported - A side state: Indicates a side whose label type is recognized by RSM, but whose label ID is not recognized by RSM. Indicates a new side that RSM has not seen before, but whose format it recognizes.

Import Pool - If RSM identifies the format or application associated with a side but has never actually detected the side before, it places the piece of media in the import pool. For example, if you place a tape written by Windows Backup on one computer into a library attached to a second computer, the instance of RSM on the receiving computer recognizes that the tape was written using Microsoft Tape Format (MTF) and places it in the proper media type specific import pool. All sides of a piece of media are placed in the same pool.

Inaccessible - A physical media state: An additional state for two-sided media. Although one side of a two-sided medium is mounted and accessible to an application, it is impossible to also make the second side accessible. A request to mount the second side cannot be completed until the first side is dismounted. For example, an application mounts side A of a two-sided medium. The snap-in shows the media state of side A as loaded, and side B as inaccessible. The side states are unaffected. If the side state of side B is available before the mount, the snap-in shows the side is still available after the mount.

Incompatible - A side state: Indicates a side that is not compatible with the library in which it resides. If a medium is found to be incompatible with the current library, RSM sets its sides states to incompatible. This can happen if a medium has a form factor (size and shape) identical to that supported by a library, but different in capacity or the way information is recorded for that library. The media containing the side should be immediately ejected from the library.

Inject - RSM uses a library's port (if one exists) for injecting and ejecting media, otherwise it uses the door. Selecting an inject task on a library with a door but no port results in the same behavior as if you selected a door access instead. You can inject media on libraries with a port using the Inject Media wizard.

In Use - A physical media state: Indicates that RSM is in the process of moving a medium.

In Process - Indicates a work item is in process while RSM is actively working on its completion.

Inventory - You can use RSM to perform a physical inventory of a library to ensure all media in the library is accounted for. There are two inventory types: fast and full. You can choose an inventory type in the library property page using a snap-in. Fast inventory checks only for slot state changes, from empty to full and vice versa. Full inventory actually identifies each medium, which can be time consuming unless the media have bar code labels. A full inventory with bar coded media only reads the bar codes. Full inventories with non-bar coded media reads the on-medium identifier (OMID) on each medium in the library.

Library - In its simplest form, a library is composed of some media and a means to read and write the media (for example, a CD-ROM drive that contains a disk). A more complex example of a library is a robotic-based tape library that holds several tapes, has one or more tape drives, and has a mechanical means to move tapes into and out of the drives. Specifically, libraries are composed of media, slots, drives, transport, bar code readers, doors, and ports. For additional information, please refer to the "Offline Media," "Online Library," and "Standalone Library" terms in this article.

Label Type - Each application can write to media using its own internal format. The label type identifies the format used on the media. MTF is a common format type that is used by Windows Backup and RSS applications.

Label ID - This is a unique identifier for the media. For non-writable media, this may be a serial number.

Loaded - A physical media state: Indicates that the medium is in a drive and the contents of one of its sides is accessible.

Logical_media - When an application begins to use a piece of media, RSM creates a logical representation of the side. An application uses this logical representation to isolate itself from the media's physical characteristics. An application creates logical media through a process called allocation. This allows physical media to have one or more logical partitions to be addressed and used separately. When the application is finished with the logical media, it can deallocate it. There is a maximum of one logical_media assignment for every side of physical_media.

Maximum Usage Count - RSM maintains a usage count for each cleaner cartridge. When a cleaner reaches its maximum usage count, RSM generates an operator request. If you eject a cleaner cartridge before it reaches its maximum usage count, RSM releases the usage count information.

Media or Medium - RSM represents removable media in two ways: physically and logically. For more information, please refer to the "Physical_media" and "Logical_media" terms in this article.

Media Change Detection - Many removable media devices (including all devices connected to the computer using SCSI and IDE) cannot detect when media in them are inserted or removed. Instead, the host computer detects such changes either by querying the device specifically for this information or by performing some other operation on the drive. Because RSM controls changers and detects when media enter and leave drives, this is not a problem for drives in changers. However, it is an issue for standalone drives. RSM may have incorrect information about the contents of a standalone drive if the state of the drive changes (for example, when a user pushes the eject button on the front of the drive). You can perform an inventory operation or a refresh on the standalone drive library to bring the state up to date.

Media label - Refer to the "On-Media Identifier (OMID)" term in this article.

Media Label Library (MLL) - A media label library is a dynamic link library (DLL) that can interpret the format of a media label written by an RSM application. RSM uses MLLs to read application media labels and translate the label type and label ID of a medium to create an application on-media identifier. You must develop an MLL for any application that uses a media format that is not supported by RSM (RSM supports FAT, NTFS, and CDFS for disk media). RSM includes three MLL files to interpret supported media labels (Mll_hp.dll, Mll_mtf.dll, and Mll_qic.dll). When RSM reads a media label (OMID), it communicates with each registered media label library to find out which application wrote the media label.

Media Pool - A media pool is a logical collection of media that share certain attributes. A media pool can hold media in more than one library, but always holds media of only one type. Each medium residing in any physical location belongs to a media pool. There are two classes of media pools: system and application. System media pools are created by RSM for its own use and include free, import, and unrecognized pools. Application pools are created by applications to group media. This is especially important if several applications are sharing the libraries attached to a computer and the media they contain. Media pools can form hierarchies. You can use a media pool to hold other media pools or to hold media. An application that needs to group media of several types into one collection can create an application pool for the entire collection and then additional media pools within it (one for each media type). RSM actually uses this technique for its system pools (for example, there are pools for each media type within the free pool).

Media Sides - Each media type has some number of sides. Some media types (for example, MO disks) have two sides, while others have a single side. A media type is single sided if its entire contents are accessible, no matter how you insert it into the drive (for example, tape media). You can only put a tape into a drive successfully if it is oriented correctly, and when it is in the drive the tape's full contents are accessible. Physical media and the sides they contain are tracked in RSM and can take on various states when they are inserted into a library and used.

Media Type - RSM supports a wide variety of media types, each with its own characteristics. Examples include: DVD-RAM, 8MM AIT1, and Travan.

Media States - Please refer to the "Physical Media States" term in this article.

Mount - An application or operator can issue a mount command to move physical media from a library slot to a drive.

Mounted - A physical media state: Indicates the medium is in a drive but may not yet be accessible. You can load the media after it is mounted, so the application can gain access to the media.

Microsoft Tape Format (MTF) - Commonly used by Windows Backup and RSS when writing to tape media.

Offline Media - This is a collection of media that RSM has cataloged but is not currently in any library. For example, a back-up tape that is removed from a standalone library and placed on a bookshelf is offline media. When a user or administrator moves this tape into a library, RSM changes its physical location to be the library where the medium is placed. When a medium is taken out of a library, RSM notes that it now resides in the offline media physical location.

Online Library - An online library contains at least some media, slots to hold media, one or more drives, a transport, and a door or a port (it can have both, some have multiple ports). These libraries are sometimes referred to as jukeboxes or changers. No human intervention is required to place a medium in a library in one of its drives. These libraries are also referred to as robotic libraries.

On-Media Identifier (OMID) - On-media identifiers are labels that are electronically recorded on each medium side in an RSM system. Each label is composed of at least two parts: a label type and a label ID. A label type identifies the format used to record information on the medium. A label ID is a name that uniquely identifies each medium. MLLs detect tape label types and IDs. An MLL is a DLL that RSM loads to recognize OMIDs. Each application can have its own MLL if necessary. Generally, there is an MLL for each label format. RSM supplies several MLLs, including one for MTF. If an application uses straight MTF, there is no need for it to supply its own MLL. RSM does not record OMIDs for read-only or write once read many (WORM) media. RSM uses the volume and serial number information that is already associated with the media. For additional information, please refer to the "Media Label Library (MLL)" term in this article.

Operator Requests - Even with robotic libraries, a human is sometimes needed to either help complete a request or perform some maintenance or support activity. For example, an application may send a request to mount a medium that is in an offline media physical location. RSM places a request for a human to insert the medium into the online library. Some operator request states include: Submitted and Refused.

Physical_media - Physical media is a tangible item that stores data. This is what is inserted and removed from libraries, and mounted in drives. Each piece of media is of a certain type, such as 8mm tape, magnetic optical disk, CD-ROM, and so on. Physical media can contain sides or Logical_media. Physical media and the sides they contain are tracked in RSM and can take on various states when they are inserted into a library and used.

Physical Media States - The states associated with physical media reflect the fact that the operations performed on them usually involve movement. Examples of physical media states include: idle, inaccessible, in-use, mounted, loaded, and unloaded. For additional information, please refer to the "Side States" term in this article.

Port - A port provides very controlled access to media in a library. When you add media to a library through a port, you do not place media directly into a library slot. Instead, you put media in the port and the library uses the transport to move media from the port to a slot. Some libraries have several ports, and some do not have any ports. An important distinction between a door and a port is what RSM knows about the contents of a library when a door or port is closed. When a port is closed, RSM still knows much about the contents of the library. If you insert a tape into a tape library using a port, RSM detects that the only thing that changed is the addition of one tape when the port is closed. When a door is open and closed, RSM does not detect anything about the contents of the library. In a tape library, for example, different tapes could have replaced all media that were in the library before the door was opened.

Prepare - Unrecognized or new raw media must be prepared before an application can use the media. After a piece of media is prepared, it has a free media label written and then it is moved to the free pool. If existing previously used media is prepared, data on the media is destroyed when the new free media label is written.

Queued - A work item is queued between the time the application issues a request until RSM examines the request.

Refused - Operator request state: Indicates an administrator has specified that the requested action will not be performed.

Reserved - A side state: A side of a two-sided media that is unavailable for allocation to all but the application that has allocated the other side.

Sides - Please refer to the "Media Sides" term in this article.

Side States - Because data is stored on a medium side, states associated with sides reflect usage rather than physical location. For more information, please refer to the associated definition for each of the following states in this article: Allocated, Available, Completed, Decommissioned, Unrecognized, Imported, Incompatible, Reserved, and Unprepared.

Slots - Slots are storage locations. For example, a tape library has one slot for each tape the library can hold. Sometimes slots are organized into collections of slots called magazines, which can be removed from the library. The RSM model does not specifically include these magazines. Although a standalone drive library has no slots, most libraries have four or more slots.

Standalone Library - This is a device that only holds one piece of physical_media at a time, and usually requires human intervention to change the media. A CD-ROM drive is a good example of a standalone library.

Submitted - Operator request state: Indicates RSM is waiting for an administrator to take the action requested.

System Pools - System pools are used to hold media that are not currently being used by any application. The unrecognized and import pools are temporary holding places for media newly placed in a library, and the free pool holds media that are unused and available to applications.

Transport - A transport is the robotic device that gets a medium from its slot to a drive and back again.

Unloaded - Indicates that a medium is still in a drive, but the contents of the side that is available is no longer accessible.

Unprepared - A side state: Indicates a side that is not claimed for use by any application but does not contain a free label. This is a temporary state that occurs only if RSM cannot write a free label on a piece of media being placed in the free pool. Applications cannot allocate unprepared media. For more information, please refer to the "Prepare" term in this article.

Unrecognized - A side state: Indicates a side whose label type and label ID is not recognized by RSM. RSM usually places media of this type in the unrecognized pool.

Unrecognized Pool - Holds media whose label type and label ID is not recognized by RSM. Media in this pool must be prepared before an application can use it. An unrecognized medium is automatically deleted from the RSM database when it is ejected from an online library or standalone library. For additional information, please refer to the "Prepare" term in this article.

Waiting - When RSM examines a request and finds that one or more of the resources needed to satisfy the request is busy (the drive the application requested a medium be mounted in is being used by another application), the request enters the waiting state.

Work Queue Items - When applications make library requests, RSM places the requests in a work queue. For example, a request to mount a medium in a library results in a mount work queue item. The RSM service performs the operations it finds in the work queue. For additional information, please refer to the associated definition for each of the following states that a work queue item can have while it is being handled by RSM: Queued, In Process, Waiting, and Failed.

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