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How Removable Storage Works

Updated: March 28, 2003

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

How Removable Storage Works

In this section

The data storage and management features in the Windows Server 2003 operating system provide you with various ways to manage and store data. With Removable Storage, a primary component of this feature set, you can track your removable storage media (tapes and optical disks) and manage the hardware libraries, such as changers and jukeboxes, which contain them.

With Removable Storage, you can:

  • Label, catalog, and track media.

  • Control library drives, slots, and doors.

  • Perform drive-cleaning operations.

Removable Storage works together with your data-management applications such as Backup. You use data-management applications to manage the actual data stored on the media. Removable Storage makes it possible for multiple applications to share the same storage media resources, which can reduce your costs. It also provides a common interface for managing those resources, so that you can manage your storage media more efficiently.

For these processes and interactions to work as described, Removable Storage should reside in an optimal environment. An optimal environment for Removable Storage is defined as follows:

  • Windows Server 2003 is correctly installed and the Removable Storage service is running.

  • All other dependencies are in place, properly designed and deployed, and functioning normally.

  • Server hardware is sized appropriately and there are no disk, CPU, memory, or network bottlenecks that affect the performance of the technology.

Removable Storage Terms and Definitions

For a complete listing of Removable Storage Terms and Definitions, see MSDN and type Removable Storage Glossary in the Search for text box.

Removable Storage Architecture

From an architectural standpoint, Removable Storage is divided into three areas:

  • Removable Storage components: The Removable Storage Microsoft Management Console (MMC) snap-in, the Removable Storage Application Programming Interface (API) and service, the Removable Storage database, and a data-management application (such as Backup).

  • Windows components and services: Win32 tape and disk APIs, tape and disk drivers, changer drivers, Event Viewer, the registry, and Group Policy.

  • Libraries: A robotic or automated library, a stand-alone tape drive, or a stand-alone DVD-RW drive, for example.

The following figure shows the components within these three areas and how the areas and components interact.

Removable Storage Architectural Diagram

Removable Storage Architectural Diagram

The following table lists the components that are included in Removable Storage.

Removable Storage Components

 

Component Description

Removable Storage MMC snap-in

Provides an administrative interface to Removable Storage. Administrators can use the snap-in to insert and eject media, perform inventories, mount and dismount media, clean drives and check status information. Removable Storage objects can be physical objects (such as libraries, drives, and media) or groups of media (called media pools).

If only one removable storage device is being utilized, it is unlikely that you will ever be required to use the snap-in because each removable storage client application can take care of routine tasks by itself. For example, a simple backup application should not require a user to go to the snap-in to place media in a drive. In general, you will only need to use the snap-in if a system is running more than one removable-storage client application (for example, Backup and a document management system), or if the system has a sophisticated robotic library that requires administrative management.

The MMC snap-in can help administrators perform the following tasks:

  • Complete or refuse operator requests.

  • Point and click operations such as inserting media, ejecting media, drive cleaning, and dismounting media, moving media from one pool to another.

  • Cancel work queue items.

  • Enable and disable drives and libraries.

Removable Storage API

Provides a programmatic interface for applications to use to access the services and media in a Removable Storage system. It is a dynamic-link library (DLL) that contains a group of functions that you can use to build your data management application. These functions perform the following operations:

  • Mount and dismount media.

  • Clean drives.

  • Insert and eject media.

  • Inventory libraries.

  • Enable and disable libraries, drives, and media.

  • Access information in the Removable Storage database.

When you develop your media management application using the Removable Storage API, you gain the following benefits:

  • Multiple applications can share the same library, drive, and media resources.

  • Code written to the Removable Storage API for a specific library can execute on a wide range of libraries, both those that exist now and those that are introduced in the future.

  • A single computer can track multiple types of media.

  • A single computer can track media that are inside or outside a media library unit.

Removable Storage service

Manages and catalogs removable media and operates automated removable media services. If this service is stopped, programs that are dependent on Removable Storage, such as Backup and Remote Storage, will operate more slowly. If this service is disabled, any services that explicitly depend on it will fail to start.

The Removable Storage service depends on the Remote Procedure Call (RPC) service to function correctly.

Removable Storage database

Contains information about the objects in a Removable Storage system. Removable Storage maintains the data in the database and updates it whenever the administrator, an application, or a device makes a change in a Removable Storage system. For example, if the administrator wants to mount a piece of media in a library, Removable Storage mounts the media and updates the database to reflect the change. The database includes the following information:

  • Library, drive, and media configuration and state.

  • Media pool configuration and contents.

  • Library requests.

  • Library worklists.

  • Operator requests.

Backup (storage management application)

Helps you protect data from accidental loss if your system’s hardware or storage media fails. For example, you can use Backup to create a duplicate copy of the data on your hard disk and then archive the data on another storage device. The backup storage medium can be a logical drive such as your hard disk, a separate storage device such as a removable disk, or an entire library of disks or tapes organized and controlled by a robotic changer. If the original data on your hard disk is accidentally erased or overwritten, or becomes inaccessible because of a hard disk malfunction, you can easily restore the data from the archived copy.

The following table lists the items that are included in Windows components and services.

Windows Components and Services

 

Service Description

Win32 tape and disk management APIs

Comprises four separate APIs: CreateFile, DeleteFile, GetDiskFreeSpace, and GetDiskFreeSpaceEx.

To find more information about these APIs, see “Removable Storage Interfaces” later in this section.

Tape and disk drivers

Enables a specific device, such as a stand-alone tape or disk drive, to communicate with the operating system. Although a device might be installed on your system, Windows cannot use the device until you have installed and configured the appropriate driver. If a device is listed in the Windows Catalog, a driver is usually included with Windows. Device drivers load automatically (for all enabled devices) when a computer is started, and then run in a manner that is transparent to users.

(The Windows Catalog website has hardware and software compatibility information for the Windows 2000 Server family, Windows XP, and the Windows Server 2003 family.)

Changer driver

Enables a specific device, such as an automated or robotic library, to communicate with the operating system. Although a device might be installed on your system, Windows cannot use the device until you have installed and configured the appropriate driver. If a device is listed in the Windows Catalog, a driver is usually included with Windows. Device drivers load automatically (for all enabled devices) when a computer is started, and thereafter run in a manner transparent to users.

Event Viewer

Provides a user interface for you to view and manage event logs, gather information about hardware and software problems, and monitor security events. Event Viewer maintains logs about program, security, and system events.

Registry

Contains information about the configuration of a computer. The registry database contains information that Windows continually references during operation, such as:

  • Profiles for each user.

  • Programs installed on the computer and the types of documents each can create.

  • Property settings for folders and program icons.

  • Hardware that exists on the system.

  • Ports that are being used.

The registry is organized hierarchically as a tree and is made up of keys and their subkeys, hives, and entries.

Group Policy

Specifies settings for groups of users and computers. These groups include software policies, scripts, user documents and configurations, application deployment, and security configurations.

To find more information about how Removable Storage uses Group Policy, see Removable Storage Tools and Settings in “Removable Storage Tools and Settings.” See also, Group Policy Settings Reference in the Tools and Settings Collection.

The following table lists the components that are included in Libraries.

Libraries

 

Library Description

Robotic or automated library

Automated units that hold multiple tapes or disks. Some have multiple drives. These libraries are sometimes called changers or jukeboxes, and commonly use robotic subsystems to move media stored in the library’s storage slots. Automated libraries can also consist of other hardware components that are managed by Removable Storage, such as doors, inject/eject ports, cleaner cartridges, and bar-code readers.

Stand-alone tape drive

A single-drive, nonautomated unit that holds a single tape. With this device, you manually insert a tape into the unit.

Stand-alone disk drive

A single-drive, nonautomated unit that holds a single disk. With this device, you manually insert a disk into the unit.

Removable Storage Protocols

Removable Storage does not utilize any networking protocols.

Removable Storage Interfaces

The following APIs are associated with Removable Storage.

(To find more information about Removable Storage interfaces, see MSDN and type Removable Storage Manager Functions in the Search for text box.)

Note

  • The Removable Storage functions were defined when the technology was previously named NTMS. As a result, many function names contain the prefix “Ntms”. Similarly, the “scratch” pool was renamed “free”, and the “foreign” pool was renamed “unrecognized”. The term “partition” was replaced with the term “side”.

Removable Storage can automatically clean tape drives that become dirty through use. You can use the following functions to control drive cleaning.

Cleaner Management Functions

 

API Name   Description

CleanNtmsDrive

Queues a cleaning request for the specified drive for cleaning.

EjectNtmsCleaner

Ejects the cleaning cartridge from the currently reserved cleaner slot.

InjectNtmsCleaner

Allows a cleaner cartridge to be inserted into the specified library unit.

ReleaseNtmsCleanerSlot

Removes an existing slot reservation for a cleaning cartridge. The slot can then be used for data cartridges.

ReserveNtmsCleanerSlot

Reserves a single slot in a library unit for a drive cleaner cartridge.

Removable Storage uses a database to store information about the removable media devices and cartridges in a system. Like any system resource, this database should be backed up in case it becomes lost or corrupted. You can use the following functions to backup and recover the Removable Storage database.

Database Backup and Recovery Functions

 

API Name   Description

ExportNtmsDatabase

Creates a consistent set of database files in the Removable Storage database directory.

ImportNtmsDatabase

Causes Removable Storage to import the database files from the database Export directory at the next restart of the Removable Storage.

You can use the following functions to get notifications when Removable Storage database objects change.

Database Notification Functions

 

API Name   Description

CloseNtmsNotification

Closes the specified open notification channel.

OpenNtmsNotification

Opens a channel to receive Removable Storage object change notifications for objects of the specified type.

WaitForNtmsNotification

Waits for the next object change notification.

Library control functions control injecting, ejecting, and moving media. They also enable and disable drive and changer resources. You can use the following library control functions.

Library Control Functions

 

API Name   Description

AccessNtmsLibraryDoor

Unlocks the door of the specified library. If the library is busy, Removable Storage queues the request and returns successfully.

CancelNtmsLibraryRequest

Cancels outstanding Removable Storage requests, such as calls to the CleanNtmsDrive function. If the library is busy, Removable Storage queues the cancellation and returns success.

DeleteNtmsDrive

Deletes a drive from the Removable Storage database. The drive must have a dwOperationalState of NTMS_NOT_PRESENT.

DeleteNtmsLibrary

Deletes a library, and all the devices contained in the library, from the Removable Storage database. All media in the library is moved to the offline library.

DeleteNtmsRequests

Deletes a request or a list of requests from the Removable Storage database. Library or operator requests that are in a completed, failed, refused, or canceled state are removed. Submitted requests, queued requests, waiting requests, and in-progress requests cannot be deleted.

DismountNtmsDrive

Queues a command to move the media in the specified drive to its storage slot. This function should be paired with the MountNtmsMedia function.

EjectDiskFromSADrive

Ejects the media that is in a stand-alone removable drive.

EjectNtmsMedia

Ejects the specified medium from the port of the current library. If the library is busy, Removable Storage queues EjectNtmsMedia and returns a state of success.

GetNtmsRequestOrder

Gets the order that the specified request will be processed in the library queue.

GetNtmsUIOptions

Obtains the list of computer names to which the specified type of user interface is being directed for the given object. A call to GetNtmsUIOptions returns the list of destinations for the instance determined by the lpObjectId and dwType parameters.

If there are no destinations in the list for the specified instance, the function returns ERROR_SUCCESS along with a list length of zero.

GetVolumesFromDrive

Retrieves the volume and drive letter for a given Removable Storage media drive.

IdentifyNtmsSlot

Identifies the media in the specified slot in a library. The command returns a state of success when the identification is complete.

InjectNtmsMedia

Allows media to be inserted into the port of the specified library. If the library is busy, Removable Storage queues InjectNtmsMedia and returns a state of success.

InventoryNtmsLibrary

Queues an inventory of the specified library. If the library is busy, Removable Storage queues InventoryNtmsLibrary and returns success.

SetNtmsUIOptions

Modifies the list of computer names to which the specified type of UI is being directed for the given object.

SetNtmsRequestOrder

Sets the order that the specified request will be processed in the library queue.

Your media label library must support the following functions. Removable Storage uses these functions to communicate with media label libraries.

Media Label Library Functions

 

API Name   Description

ClaimMediaLabel

Determines whether a specified media label was created by the media’s associated application.

MaxMediaLabel

Determines the maximum size of the media label for the applications that are supported by the media label library.

Media services functions are used for mounting and dismounting media and managing media pools. You can use the following media services functions.

Media Services Functions

 

API Name   Description

AddNtmsMediaType

Adds the specified media type to the specified library if there is not currently a relation in the library object. The function then creates the system media pools if they do not exist.

AllocateNtmsMedia

Allocates a piece of available media.

ChangeNtmsMediaType

Moves the specified Physical Media Identifier (PMID) to the specified target media pool and sets the PMID’s media type identifier to the media type of the target media pool.

(A PMID is defined as a representation of media.)

CreateNtmsMedia

Creates a PMID and side (or sides) for a new piece of offline media. The media is placed in the media pool that is specified for the lpPhysicalMedia parameter.

A tape or disk side is where actual information is stored.

CreateNtmsMediaPool

Creates a new application media pool.

DeallocateNtmsMedia

Deallocates the side that is associated with the specified logical media.

DecommissionNtmsMedia

Moves a side from the Available state to the Decommissioned state.

DeleteNtmsMedia

Deletes a physical piece of offline media from Removable Storage by removing all references to the specified media from the database.

DeleteNtmsMediaPool

Deletes the specified application media pool.

DeleteNtmsMediaType

Deletes the specified media type relation from the specified library, provided that the library does not contain any physical media objects of the specified media type.

DismountNtmsMedia

Queues a command to move the specified media in a drive to its storage. This function should be paired with the MountNtmsMedia function.

GetNtmsMediaPoolName

Retrieves the specified media pool’s full name hierarchy.

MountNtmsMedia

Synchronously mounts one or more pieces of media.

MoveToNtmsMediaPool

Moves the specified medium from its current media pool to the specified media pool.

SetNtmsMediaComplete

Marks a piece of logical media as complete.

SwapNtmsMedia

Swaps the sides associated with the two specified Logical Media Identifiers (LMIDs). The specified LMIDs must be in the same media pool.

(An LMID is defined as a logical representation of a physical storage location. The Media Service generally defines sides of the logical media for use by the application. The intent of logical media is to allow the underlying physical medium of the data to change without affecting the application.)

You can use the following functions to enumerate, get, and set information about Removable Storage objects.

Object Management Functions

 

API Name   Description

DisableNtmsObject

Disables the specified Removable Storage object.

EnableNtmsObject

Enables the specified object.

EnumerateNtmsObject

Enumerates the Removable Storage objects contained in the lpContainerId parameter.

GetNtmsObjectAttribute

Retrieves the extended attribute (named Private Data) from the specified Removable Storage object.

GetNtmsObjectInformation

Returns the information structure for the specified object.

GetNtmsObjectSecurity

Reads the security descriptor for the specified Removable Storage object.

SetNtmsObjectAttribute

Creates an extended attribute (named Private Data) in the specified Removable Storage object.

SetNtmsObjectInformation

Changes the information structure of the specified object.

SetNtmsObjectSecurity

Writes the security descriptor for the specified Removable Storage object.

Removable Storage identifies media in a system by reading an on-media identifier (OMID). You can use the following function to update the RSM database when a new OMID is written.

On-Media-Identifier Management Functions

 

API Name   Description

UpdateNtmsOmidInfo

Updates the Removable Storage database with label information immediately after writing to the newly allocated medium.

You can use the following functions to manage and control requests to system operators.

Operator Request Functions

 

API Name   Description

CancelNtmsOperatorRequest

Cancels the specified Removable Storage operator request.

SatisfyNtmsOperatorRequest

Completes the specified Removable Storage operator request.

SubmitNtmsOperatorRequest

Submits a Removable Storage operator request.

WaitForNtmsOperatorRequest

Waits for the specified Removable Storage operator request.

Before calling any other functions, an application must open a Removable Storage session, and the session must be closed before the application exits. You can use the following session management functions to open and close Removable Storage sessions.

Session Management Functions

 

API Name   Description

CloseNtmsSession

Closes the specified Removable Storage session.

OpenNtmsSession

Sets up a session with a Removable Storage server.

Removable Storage Processes and Interactions

The following is a general description of how Removable Storage functions at a basic level.

As noted earlier, Removable Storage works together with your data-management applications, such as Backup. You use data-management applications to manage the actual data stored on the media. Removable Storage makes it possible for multiple programs to share the same storage media resources, which can reduce your costs.

The Removable Storage MMC snap-in is an administrative interface to Removable Storage and is used to perform a number of important tasks. With the Removable Storage MMC snap-in, you can:

  • Create media pools and set media pool properties.

  • Insert and eject media in an automated library.

  • Mount and dismount media.

  • Clean tape drives.

  • View the state of media and libraries.

  • Enable and disable drives and libraries.

  • Perform library inventories

  • Set security permissions for users.

  • Complete or refuse operator requests

  • Cancel work queue items.

Removable Storage organizes all the media in your libraries into different media pools. Removable Storage also moves media between media pools in order to provide the amount of data storage that your applications require.

You cannot use Removable Storage to manage volumes, such as for media siding or striping. Also, you cannot use Removable Storage to manage files, such as for data backup or disk-extender operations. These services are performed by data-management applications such as Backup or Remote Storage. Remote Storage is not available on computers running Windows XP Professional, Windows Server 2003, Web Edition; or Windows Server 2003, Standard Edition.

You must run all your data-management programs on the same computer that connects to your library. Removable Storage does not support multiple data-management programs running on different computers that are connected to the same library.

For these processes and interactions to work as described, Removable Storage should reside in an optimal environment. An optimal environment for Removable Storage is defined as follows:

  • Windows Server 2003 is correctly installed and the Removable Storage service is running.

  • All other dependencies are in place, properly designed and deployed, and functioning normally.

  • Server hardware is sized appropriately and there are no disk, CPU, memory, or network bottlenecks that affect the performance of the technology.

Removable Storage Technologies

The following is a more detailed description of specific technologies, features or attributes that either form a part of, or are closely identified with, Removable Storage.

Libraries

In its simplest form, a library consists of data storage media and the device used to read from and write to the media. The group of libraries and associated media that are managed by a Removable Storage installation is called a Removable Storage system. There are two major types of libraries:

  • Automated libraries are automated units that hold multiple tapes or disks, and some have multiple drives. These libraries are sometimes called changers or jukeboxes, and commonly use robotic subsystems to move media stored in the library’s storage slots. Automated libraries can also consist of other hardware components that are managed by Removable Storage, such as doors, inject/eject ports, cleaner cartridges, and bar-code readers.

  • Stand-alone drive libraries, or stand-alone drives, are single-drive, nonautomated units, such as tape or CD-ROM drives, that hold a single tape or disk. With these, you manually insert a tape or disk into the unit.

Not only can Removable Storage manage multiple libraries, but it can also track offline media that are not currently contained in a library. These media might be on a shelf or in a drawer, for example. Every tape or disk that is offline can belong to a library.

Managing libraries

Removable Storage provides comprehensive control and management of libraries. You can enable or disable entire libraries or only specific drives within a library. You can change the media type for a library. You can also open the door on an automated library and set various time-out values.

Removable Storage attempts to automatically configure all libraries, including automated libraries, when you first start Removable Storage and when you add or remove a library from a computer that is running Removable Storage.

Removable Storage can always automatically configure stand-alone drives, but you can use the automatic configuration feature of Removable Storage for automated libraries only if you connect all drives on the same SCSI bus as the associated media changer, or if all drives have unique serial numbers. Also, you must use automated libraries that support drive-element address reporting. For information on whether your library supports this feature, consult the library manufacturer.

Note

  • Because not all library configurations support the automatic configuration feature, Removable Storage provides a method for manually configuring libraries. However, do not use this method unless it is absolutely necessary because manually configured libraries do not recognize system configuration changes. Manually configured libraries also involve registry changes.

  • Removable Storage numbers slots and drives starting from either 0 or 1. However, the device (firmware) has its own addresses that it uses. The Mcd.sys driver maps these addresses to the more user-friendly numbers (starting from 0 or 1) used by Removable Storage.

Inventorying libraries

You can create an inventory of all media in a library. Removable Storage supports two inventory methods:

  • Fast inventory. Removable Storage checks the storage slots and reads the on-media identifier on media in slots that were previously empty.

  • Full inventory. Removable Storage mounts each tape or disk in your library and reads the on-media identifier.

Media Pools

A media pool is a collection of tapes or disks that have the same management properties. All media in a Removable Storage system belong to a media pool, and each media pool holds only one type of media. Data management programs use media pools to gain access to specific tapes or disks within a library.

Using media pools, you can define properties that apply to a set of media. This is useful because Removable Storage allows multiple programs to share the same media within a single library. A library can include media from different media pools, each with different properties. A single media pool can span multiple libraries. You can also create hierarchies of media pools, or media pools that contain other media pools. For example, you can create a media pool for each specific media type required by a program, and then create another media pool that contains this collection of media pools. Media pools can contain either media or other media pools, but not both.

A Removable Storage system provides two classes of media pools: system and application.

System media pools include free media pools, unrecognized media pools, and import media pools. Removable Storage creates one free, one unrecognized, and one import media pool for each media type in your Removable Storage system. The system media pools are used to hold media that are not currently being used by an application.

Application media pools are created by data-management applications such as Backup and Remote Storage, the latter for computers running Windows Server 2003, Enterprise Edition; Windows Server 2003, Datacenter Edition; the 64-bit version of Windows Server 2003, Enterprise Edition; or the 64-bit version of Windows Server 2003, Datacenter Edition.

The different media pools are defined as follows:

  • Unrecognized media pools contain blank (new) media and media that Removable Storage does not recognize. You should immediately move a new tape or disk from an unrecognized media pool to a free media pool so that the tape or disk can be used by applications, or remove it from the library.

Unrecognized media are automatically deleted from the Removable Storage database when they are ejected from a library.

  • Import media pools contain media that Removable Storage recognizes in the database, but that have not been used before in a particular Removable Storage system. For example, media in an import media pool could be media from one office location that are introduced into a Removable Storage system at another office location.

You can move media from import media pools to free media pools or application media pools so applications can use them.

  • Free media pools contain media that are not currently in use by applications and do not contain useful data. Media in free media pools are available for use by applications.

You can configure application media pools to automatically draw media from free media pools when there are not sufficient media available in a particular application media pool. If you do not implement this configuration, you must manually move media from a free media pool when needed.

  • Application media pools determine which media can be accessed by which applications. You or data management applications create them.

Media in an application media pool are controlled by that application or by an administrator. An application can use more than one media pool, and more than one application can share a single media pool. For example, Backup might use one media pool for a full backup and another media pool for an incremental backup, each containing a different media type.

There can be any number of application media pools in a Removable Storage system. Media that are currently reserved for use by an application, called allocated media, cannot be moved between media pools. Allocation controls how the media are used by applications.

The following figure shows how media can move from one media pool to another.

How Media Can Move From One Media Pool To Another

How Media Can Move From One Media Pool To Another
Managing media pools

After configuring your libraries, you can configure your media pools. Before creating a new media pool, you should answer the following questions:

  • What media types are available in your Removable Storage system?

  • Should media be automatically drawn from a free media pool when there are not sufficient media in an application media pool? (It is recommended that you implement this configuration.)

  • Should media be automatically returned to a free media pool when they are no longer needed by an application?

Note

  • You cannot delete system media pools.

Managing tapes and disks in a media pool

After you create and configure your media pools, you can move media to a specific media pool. It is important that you have a sufficient amount of media in a free media pool so that applications can use media in this pool when needed.

Next, you can use a data management application such as Backup to allocate media to the application media pool created for (or by) that application. Allocating media to an application media pool reserves all media in that media pool for exclusive use by that application. See the documentation for your particular data management application for information on how to reserve media for that application.

Removable Storage provides comprehensive control of tapes or disks in your library. You can enable or disable specific media in your library, insert and eject media, and mount and dismount media.

A tape or disk can be inserted in or ejected from an automated library using either a library door or an inject/eject port. A library door allows unrestricted access to the media inside. You can add or remove media directly from a storage slot using a door access. An inject/eject port allows controlled access to the media inside. You insert a tape or disk in the port and then the library uses the drive bay to move the media to a storage slot.

A tape or disk can be mounted on or dismounted from a particular drive in a library. You can use the same media many times before dismounting them. You can also mount and dismount the same media many times before deallocating them.

Note

  • Removable Storage requires that CDs are formatted with the CD-ROM file system and that rewritable optical media (such as magneto-optical disks) are formatted with the FAT, FAT32, or NTFS file system.

  • Windows does not directly support the use of media that can be written to only once, such as write once, read-many (WORM), CD-R, and DVD-R disks. If you plan to use these, you must acquire other software that supports these technologies.

Media Identification

Removable Storage uses two identification methods to track media and perform inventories: on-media identifiers and bar codes.

On-media identifiers

On-media identifiers are electronically recorded on media the first time a tape or disk is inserted into a library. The next time the medium is inserted into the library, Removable Storage uses the on-media identifier to recognize and track the tape or disk.

An on-media identifier has two parts: a label type and a label ID. The label type identifies the specific format used to record information on the tape or disk, such as Microsoft Tape Format (MTF). The label ID is a unique identifier for the tape or disk in the Removable Storage system. If Removable Storage does not recognize the label type, it adds the medium to an unrecognized media pool. If Removable Storage recognizes the label type, but does not recognize the label ID, it puts the media in an import media pool. If Removable Storage recognizes the label type and the label ID, it updates the Removable Storage database to reflect that the medium is online and available for use.

Note

  • Removable Storage does not record on-media identifiers for read-only or write-once optical media, such as CD-ROM, DVD-ROM, CD-R, DVD-R, or WORM disks. Instead, Removable Storage uses the volume and serial number information that is already associated with the disk.

Bar codes

If your library supports bar codes, Removable Storage can use them to identify media. Media with bar codes also have on-media identifiers. Removable Storage can use either the bar codes or the on-media identifiers. Using bar codes to track media is generally much faster because each tape or disk does not have to be mounted to read the on-media identifier.

Media States

Each tape or disk in a Removable Storage system has a state associated with it that determines what operations can be performed with the media. When media are inserted into a library, Removable Storage uses the on-media identifier or bar code to determine its state.

There are two sets of media states that govern media movement and usage by Removable Storage: physical states and side states.

Physical states

The physical states identify operations performed that involve media location or movement. The following table lists and describes the five possible physical states.

Physical States

 

Physical State Description

Idle

Tape or disk is currently in a storage slot in an automated library or is shelved offline.

In-use

Tape or disk is in the process of being moved.

Loaded

Tape or disk is mounted in a drive and data is available to be read or written.

Mounted

Tape or disk is mounted in a drive, but data is not yet available to be read or written.

Unloaded

Tape or disk has been dismounted and is ready to be removed from a drive.

Side states

A tape or disk side is where actual information is stored. Side states identify operations that are performed that involve media usage rather than location or movement. The following table lists and describes the nine possible side states.

Side States

 

Side State Description

Allocated

Side is reserved for use by an application. The side is not available to any other application.

Available

Side is currently available for use by an application.

Completed

Side is in use, but cannot be used for write operations. The side is full.

Decommissioned

Side is no longer available for use because it has reached its allocation maximum.

Imported

Side’s label type is recognized, but its label ID is not recognized by Removable Storage.

Incompatible

The media type of the side is not compatible with the library. The tape or disk should be removed from the library.

Reserved

Side is unavailable for allocation except by a single application. This applies only to two-sided media where one side has already been allocated.

Unprepared

Side has been placed in a free media pool, but does not yet have a free media label. This is a temporary state.

Unrecognized

Side’s label type and label ID are not recognized by Removable Storage.

The relationship between the various media pools and side states is as follows: Import media pools can only hold media sides in the Imported state. Unrecognized media pools can only hold media sides that are in the Unrecognized state. Free media pools can only hold media sides that are in the Available (and transitional unprepared) state.

Managing Operator Requests and Queued Work

The work queue lists all library requests, or work items that are initiated by an application or by Removable Storage. A request to mount a tape in a library, for example, results in a mount work item listed in the work queue.

The following table describes the states that a work item can have.

Work Item States

 

Work State Description

Completed

The work item has been completed successfully.

Failed

Removable Storage was unable to complete the work item.

In Process

Removable Storage is actively operating on the work item.

Queued

The work item is ready to be carried out, but Removable Storage has not yet begun to operate on it.

Waiting

One or more resources needed to satisfy the request are currently in use.

Cancelled

A user has cancelled the work item.

An operator request is a message that asks you to perform a specific task. Operator requests can be issued by Removable Storage or by a program that is aware of Removable Storage, such as Backup. Removable Storage can generate an operator request when any of the following occur:

  • An application initiates a mount request for a tape or disk that is offline.

  • There are no available media online. That is, a program requires media and none exist in the appropriate application media pool or in a free media pool.

  • A library has failed and requires servicing.

  • A drive needs cleaning and no usable cleaner cartridges are available in the library.

You can respond to operator requests by either completing or refusing the operator request. When you refuse an operator request, Removable Storage notifies the application that generated the request. By default, Removable Storage stores an operator request in the work queue for 72 hours after you respond to the request.

The following table describes the states that an operator request can have.

Operator Request States

 

Operator request state Description

Completed

You have indicated, or Removable Storage has detected, that the operator request was completed.

Refused

You have indicated that the operator request will not be performed.

Submitted

Removable Storage or an application has submitted an operator request for action.

You can change how operator requests are displayed on your computer, delete operator requests, cancel any pending operation listed in the work queue, and change the order of mount requests in the work queue.

Network Ports Used by Removable Storage

Removable Storage does not utilize any network ports.

Related Information

The following resources contain additional information that is relevant to this section.

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