1、American National StandardDeveloped byfor Information Technology SCSI Media Changer Commands-2(SMC-2)ANSI INCITS 382-2004ANSIINCITS382-2004ANSIINCITS 382-2004American National Standardfor Information Technology SCSI Media Changer Commands-2(SMC-2)SecretariatInformation Technology Industry CouncilApp
2、roved October 5, 2004 American National Standards Institute, Inc.AbstractThis standard defines the SCSI commands and model for independent media changer devices and at-tached media changer functions integrated into other SCSI devices.Approval of an American National Standard requires review by ANSI
3、that therequirements for due process, consensus, and other criteria for approval havebeen met by the standards developer.Consensus is established when, in the judgement of the ANSI Board ofStandards Review, substantial agreement has been reached by directly andmaterially affected interests. Substant
4、ial agreement means much more thana simple majority, but not necessarily unanimity. Consensus requires that allviews and objections be considered, and that a concerted effort be madetowards their resolution.The use of American National Standards is completely voluntary; theirexistence does not in an
5、y respect preclude anyone, whether he has approvedthe standards or not, from manufacturing, marketing, purchasing, or usingproducts, processes, or procedures not conforming to the standards.The American National Standards Institute does not develop standards andwill in no circumstances give an inter
6、pretation of any American NationalStandard. Moreover, no person shall have the right or authority to issue aninterpretation of an American National Standard in the name of the AmericanNational Standards Institute. Requests for interpretations should beaddressed to the secretariat or sponsor whose na
7、me appears on the titlepage of this standard.CAUTION NOTICE: This American National Standard may be revised orwithdrawn at any time. The procedures of the American National StandardsInstitute require that action be taken periodically to reaffirm, revise, orwithdraw this standard. Purchasers of Ameri
8、can National Standards mayreceive current information on all standards by calling or writing the AmericanNational Standards Institute.American National StandardPublished byAmerican National Standards Institute, Inc.25 West 43rd Street, New York, NY 10036Copyright 2004 by Information Technology Indus
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12、epresentation is made or impliedthat licenses are not required to avoid infringement in the use of this standard.iContentsPageForeword vIntroduction vii1 Scope. 12 Normative references. 53 Definitions, symbols and abbreviations 53.1 Definitions 53.2 Symbols and abbreviations 83.3 Keywords . 83.4 Con
13、ventions. 94 Overview 105 Media changer models. 125.1 Independent media changer 125.2 Attached media changer 125.3 Media changer elements 125.3.1 Elements overview. 125.3.2 Medium transport element . 135.3.3 Storage element. 145.3.4 Import/export element 145.3.5 Data transfer element 145.3.6 Element
14、 status maintenance requirements 145.4 Volume tag information 155.4.1 Volume tag overview 155.4.2 Primary and alternate volume tag information . 165.4.3 Volume tag information format. 165.5 TapeAlert information. 175.5.1 TapeAlert introduction 175.5.2 TapeAlert log sense format 176 Commands for medi
15、a changer logical units. 196.1 Summary of commands for independent media changers 196.2 Summary of commands for attached media changers 206.3 Commands allowed in the presence of various reservations. 216.4 EXCHANGE MEDIUM command 236.5 INITIALIZE ELEMENT STATUS command . 246.6 INITIALIZE ELEMENT STA
16、TUS WITH RANGE command . 25iiPage6.7 MOVE MEDIUM commands 266.8 POSITION TO ELEMENT command. 276.9 READ ATTRIBUTE command . 296.10 READ ELEMENT STATUS commands . 306.10.1 READ ELEMENT STATUS introduction 306.10.2 Element status data . 316.10.3 Element status page 336.10.4 Medium transport element de
17、scriptor 346.10.5 Storage element descriptor 366.10.6 Import/export element descriptor . 386.10.7 Data transfer element descriptor . 396.10.8 Identification descriptor 416.11 REQUEST VOLUME ELEMENT ADDRESS command 426.12 SEND VOLUME TAG command . 446.12.1 SEND VOLUME TAG introduction. 446.12.2 Send
18、action codes . 456.12.3 SEND VOLUME TAG parameter data. 466.13 WRITE ATTRIBUTE command . 477 Parameters 487.1 Diagnostic parameters. 487.2 Log parameters 487.2.1 Log page codes . 487.2.2 TapeAlert log page 497.3 Mode parameters. 507.3.1 Mode page codes 507.3.2 Device Capabilities mode page . 517.3.3
19、 Element Address Assignment mode page. 537.3.4 Transport Geometry Parameters mode page 55AnnexA TapeAlert Flags . 56iiiPageTables1 Volume tag information format. 162 Volume Identification Qualifier . 173 Commands for independent media changers . 194 Commands for attached media changers 205 SMC comma
20、nds allowed in the presence of various reservations. 226 EXCHANGE MEDIUM command. 237 INITIALIZE ELEMENT STATUS command . 248 INITIALIZE ELEMENT STATUS WITH RANGE command . 259 MOVE MEDIUM and MOVE MEDIUM ATTACHED command 2610 POSITION TO ELEMENT command . 2711 READ ATTRIBUTE command . 2912 READ ELE
21、MENT STATUS equivalent to the phrase “it is strongly recommended.“ 3.4 Conventions Certain words and terms used in this standard have a specific meaning beyond the normal English meaning. These words and terms are defined either in or in the text where they first appear. Names of commands, statuses,
22、 sense keys, additional sense codes, and additional sense code qualifiers are in all uppercase (e.g., REQUEST SENSE). Field names and bit names are in SMALL CAPS. Lower case is used for words having the normal English meaning. Fields containing only one bit are usually referred to as the name bit in
23、stead of the name field. Numbers that are not immediately followed by lowercase b or h are decimal values. Numbers immediately followed by lowercase b (xxb) are binary values. Numbers or upper case letters immediately followed by lowercase h (xxh) are hexadecimal values. Lists sequenced by letters (
24、e.g., a-red, b-blue, c-green) show no priority relationship between the listed items. Numbered lists (e.g., 1-red, 2-blue, 3-green) show a priority ordering between the listed items. If a conflict arises between text, tables, or figures, the order of precedence to resolve the conflicts is text; then
25、 tables; and finally figures. Not all tables or figures are fully described in the text. Tables show data format and values. NOTES do not constitute any requirements for implementors. ANSI INCITS 382-2004 10 4 Overview The SCSI media changer device class specifies a logical unit that is involved, pr
26、imarily, with the movement of removable volumes in a controlled environment without human intervention. The SCSI device classes that provide for removable volumes are block, multimedia and sequential. (See the SBC-2, MMC-4 and SSC-2 standards.) A media changer logical unit receives commands to move
27、volumes between various element types in the element address space of the media changer. The element types are storage, data transfer, medium transport, and import/export. A volume handling robotics subsystem, addressed as a medium transport element, moves volumes within a media changer. Volumes may
28、 also be moved between media changers with interconnected import/export ports. A media changer logical unit maintains an inventory of volumes and the element addresses at which they may be found. The media changer logical unit reports this inventory when requested and identifies the element addresse
29、s assigned to different types of elements. Different levels of sophistication may be implemented in how this inventory is managed, reported, detected and maintained. The elements in a media changer may be reserved to different SCSI initiator ports. For example, one data transfer element may be reser
30、ved for exclusive use by one SCSI initiator port. The data transfer device, located at that data transfer element, may then be attached to various systems for their use. In some cases, the data transfer device associated with a data transfer element may not be a SCSI device. The split between load a
31、nd unload control of the medium and read and write control by a data transfer device is a key feature of this device class. The mechanism for coordinating this kind of sophisticated activity is not specified in this standard. The media changer device class provides the means for mount/dismount manag
32、ement only. ANSI INCITS 382-2004 11 Figure 2 shows an example of an independent media changer. The data transfer elements (data transfer devices) shown may be any type of removable media device such as a tape drive, disk drive or optical drive. Supporting multiple types of removable media within the
33、 same media changer is also permitted. Also, the ports on each data transfer device may or may not attach to the same service delivery subsystem and the interfaces to the data transfer devices may or may not be SCSI target ports. The number and arrangement of elements is arbitrary. Import/Export Ele
34、mentStorage ElementsData Transport ElementsMedium TransportElementSCSITargetPortPortPortMediaChangerLogical UnitFigure 2 - Example independent media changer device The independent changer model applies to implementations where the media changer is addressed as a separate logical unit. The logical un
35、it for the media changer may be accessed via the same SCSI target port as the data transfer device, or via a different SCSI target port. This type of media changer may support more than one data transfer element. The attached media changer model permits a subset of the functions of an independent ch
36、anger to be incorporated directly into a data transfer device. Only one data transfer element is permitted. In this case, only one logical unit is used to access all functions. A media changer moves volumes among the elements accessible to it on command from an application client. Media changers sha
37、ll be capable of reporting the full or empty status of any element. ANSI INCITS 382-2004 12 5 Media changer models 5.1 Independent media changer An independent media changer is a device server that returns 8h in the PERIPHERAL DEVICE TYPE field (see SPC-2) of INQUIRY command response data. Independe
38、nt media changers respond to a LUN different from those used by a data transfer device. Communication with a data transfer device may use the same service delivery subsystem as the media changer device, or a different SCSI service delivery subsystem. Data transfer devices that are not SCSI devices a
39、re also permitted. Multiple data transfer devices may be attached to an independent changer. If a data transfer device served by the media changer is a SCSI device, the data transfer device may be addressed on a SCSI service delivery subsystem though the same SCSI target port as the media changer bu
40、t with a different LUN. The data transfer device may also be addressed through independent SCSI target ports and any LUN on the same or a different service delivery subsystem. The READ ELEMENT STATUS command response data page for each data transfer element may provide the identity of the data trans
41、fer device serviced by a media changer device. This support is optional since a data transfer device is not required to be a SCSI device. 5.2 Attached media changer An attached media changer is part of a device server that sets the MCHNGR bit to one in its standard INQUIRY data (see SPC-2). Attached
42、 media changers respond to the same LUN as a data transfer device that is not a media changer. In an attached media changer, the PERIPHERAL DEVICE TYPE field of standard INQUIRY data returns the type of the data transfer device. Two media changer commands, READ ELEMENT STATUS ATTACHED and MOVE MEDIU
43、M ATTACHED are added to the command set of the data transfer device. The other commands available depend on the model for the data transfer device. 5.3 Media changer elements 5.3.1 Elements overview A media changer has an address space separate and distinct from the physical address space of a SCSI-
44、3 service delivery subsystem. The term element is used throughout this standard to refer to one member of the media changer address space. Within a media changer, the element addresses are a set of physical locations and mechanisms within the scope of a media changer device. Each element is an insta
45、nce of one of four element types: a) medium transport element; b) storage element; c) import/export element; or d) data transfer element. Each element is a discrete physical entity with a unique element address that may provide storage for zero or one volume. A volume is in exactly one element at a
46、time. When moving from one element to another, the point in time when the volume changes element address is not ANSI INCITS 382-2004 13 specified by this standard. When requested to report element status, a volume shall be reported as being at exactly one element address. The element address shall n
47、ot be arbitrarily changed by the media changer. However, in configurations with multiple initiators, volumes may be moved by one application client without notification of other application clients. Volumes are addressed indirectly by this model. Volumes may be moved to or from any of the elements o
48、f the media changer device using element addresses. The method of detecting the presence of a volume at any element in a media changer is vendor specific. In order to ensure exclusive access to a volume, the element where the volume is located (the element address) may be reserved by a SCSI initiato
49、r port. Exclusive access shall be released if the volume is moved to an unreserved element. Exclusive access shall be retained if a volume is moved between two reserved elements. Reservation of the medium transport element used is not required to preserve exclusive access. Elements may be reserved by the PERSISTENT RESERVE OUT (see SPC-2) command. Providing independent storage for medium is optional for medium transport, import/export, and data transfer elements. The capabilities of a particular media changer may be determined from mode parameters in the Device Capabilities mode page (see
