1、ANSI INCITS 314-1998 (R2003)(formerly ANSI NCITS 314-1998)for Information Technology SCSI-3 Medium Changer Commands (SMC)ANSINCITS 314-1998American National Standardfor Information Technology SCSI-3 Medium Changer Commands (SMC)SecretariatInformation Technology Industry CouncilApproved May 19, 1998A
2、merican National Standards Institute, Inc.AbstractThis standard defines the SCSI commands and model for independent medium changer devices and at-tached medium changer functions integrated into other SCSI devices.Approval of an American National Standard requires review by ANSI that therequirements
3、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. Substantial agreement means m
4、uch 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 any respect preclude an
5、yone, 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 interpretation of any Amer
6、ican 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 name appears on the tit
7、lepage 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 American National Standard
8、s mayreceive current information on all standards by calling or writing the AmericanNational Standards Institute.American National StandardPublished byAmerican National Standards Institute, Inc.11 West 42nd Street, New York, NY 10036Copyright 1998 by Information Technology Industry Council (ITI)All
9、rights reserved.No part of this publication may be reproduced in anyform, in an electronic retrieval system or otherwise,without prior written permission of ITI, 1250 Eye Street NW, Washington, DC 20005. Printed in the United States of AmericaCAUTION: The developers of this standard have requested t
10、hat holders of patents that may berequired for the implementation of the standard disclose such patents to the publisher. However,neither the developers nor the publisher have undertaken a patent search in order to identifywhich, if any, patents may apply to this standard. As of the date of publicat
11、ion of this standardand following calls for the identification of patents that may be required for the implementation ofthe standard, no such claims have been made. No further patent search is conducted by the de-veloper or publisher in respect to any standard it processes. No representation is made
12、 or impliedthat licenses are not required to avoid infringement in the use of this standard.iContentsPageForeword .ivIntroduction vii1 Scope 12 Normative references . 33 Definitions, symbols and abbreviations. 43.1 Definitions . 43.2 Symbols and abbreviations . 73.3 Keywords 73.4 Conventions 84 Over
13、view. 95 Medium changer models 115.1 Independent medium changer 115.2 Attached medium changer 115.3 Medium changer elements 115.4 Medium transport element 125.5 Storage element 135.6 Import/export element . 135.7 Data transfer element 135.8 Element status maintenance requirements. 145.9 Volume tag i
14、nformation . 145.10 Primary and alternate volume tag information 155.11 Volume tag information format 156 Commands for medium changer logical units. 166.1 EXCHANGE MEDIUM command 186.2 INITIALIZE ELEMENT STATUS command 206.3 MOVE MEDIUM command . 216.4 POSITION TO ELEMENT command 236.5 READ ELEMENT
15、STATUS command 246.5.1 Element status data . 256.5.2 Element status page 266.5.3 Medium transport element descriptor. 276.5.4 Storage element descriptor 296.5.5 Import/export element descriptor . 306.5.6 Data transfer element descriptor 326.5.7 Identification descriptor 346.6 RELEASE ELEMENT (6) com
16、mand . 356.6.1 Logical unit release (Mandatory) . 356.6.2 Element release (Optional) 356.7 RELEASE ELEMENT (10) command . 366.7.1 Third-party release (Mandatory). 366.8 REQUEST VOLUME ELEMENT ADDRESS command . 376.9 RESERVE ELEMENT (6) command. 406.9.1 Logical unit reservation (Mandatory) 406.9.2 El
17、ement reservation (optional) . 416.10 RESERVE ELEMENT (10) command. 42iiPage6.10.1 Third-party reservation (Mandatory). 436.10.2 Superseding reservations 436.11 SEND VOLUME TAG command. 457 Parameters . 497.1 Diagnostic parameters 497.2 Log parameters. 497.3 Mode parameters 507.3.1 Device capabiliti
18、es page 517.3.2 Element address assignment page 537.3.3 Transport geometry parameters page 54Tables1 Volume tag information format . 152 Commands for independent medium changers . 163 Commands for attached medium changers . 174 EXCHANGE MEDIUM command. 185 INITIALIZE ELEMENT STATUS command 206 MOVE
19、MEDIUM command 217 POSITION TO ELEMENT command 238 READ ELEMENT STATUS command 249 Element type code 2510 Element status data 2511 Element status page 2612 Medium transport element descriptor. 2713 Storage element descriptor 2914 Import/export element descriptor 3015 Data transfer element descriptor
20、 3216 Identification descriptor fields . 3417 RELEASE ELEMENT (6) command. 3518 RELEASE ELEMENT (10) command. 3619 RELEASE ELEMENT (10) parameter list. 3720 REQUEST VOLUME ELEMENT ADDRESS command. 3821 Volume element address header . 3922 RESERVE ELEMENT (6) command 4023 Data format of element list
21、descriptors. 4224 RESERVE ELEMENT (10) command 4325 RESERVE ELEMENT (10) ID equivalent to the phrase “it is strongly recommended“.3.4 ConventionsCertain words and terms used in this standard have a specific meaning beyond the normalEnglish meaning. These words and terms are defined either in 3.1 or
22、in the text where they firstappear. Names of commands, statuses, sense keys, additional sense codes, and additionalsense code qualifiers are in all uppercase (e.g., REQUEST SENSE). Field names and bit namesare in SMALL CAPS. Lower case is used for words having the normal English meaning.Fields conta
23、ining only one bit are usually referred to as the name bit instead 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
24、(xxh) are hexadecimalvalues.Lists sequenced by letters (e.g., a-red, b-blue, c-green) show no priority relationship between thelisted items. Numbered lists (e.g., 1-red, 2-blue, 3-green) show a priority ordering between thelisted items. If a conflict arises between text, tables, or figures, the orde
25、r of precedence to resolvethe conflicts is text; then tables; and finally figures. Not all tables or figures are fully described inthe text. Tables show data format and values. NOTES do not constitute any requirements forimplementors.ANSI NCITS 314-199894 OverviewThe SCSI-3 medium changer device cla
26、ss specifies a logical unit that is involved, primarily, withthe movement of removable volumes in a controlled environment without human intervention. TheSCSI-3 device classes that provide for removable volumes are block, multi-media and sequential.(See the SBC, MMC and SSC standards.)A medium chang
27、er logical unit receives commands to move volumes between various elementtypes in the element address space of the medium changer. The element types are storage, datatransfer, medium transport, and import/export. A volume handling robotic subsystem, addressedas a medium transport element, moves volu
28、mes within a medium changer.A medium changer logical unit maintains an inventory of volumes and the element addresswhere they can be found. The medium changer logical unit reports this inventory when requestedas well as identifying the element addresses assigned to different types of elements.Differ
29、ent levels of sophistication may be implemented in how this inventory is managed, reported,detected and maintained. The elements in a medium changer may be reserved to differentinitiators. For example, one data transport element may be reserved for exclusive use by oneinitiator. The primary device,
30、located at that data transfer element, may then be attached tovarious systems for their use. In some cases, the primary device associated with a data transferelement may not be an SCSI device.The split between load and unload control of the medium and read and write control by a primarydevice is a k
31、ey feature of this device class. The mechanism for coordinating this kind ofsophisticated activity is not specified in this standard. The medium changer device class providesthe means for mount/dismount management only.ANSI NCITS 314-199810Figure 2 shows an example of an independent medium changer.
32、The data transfer elements(primary devices) shown may be any type of removable media device such as a tape drive, diskdrive or optical drive. Supporting multiple types of removable media within the same mediumchanger is also permitted. Also, the ports on each primary device may or may not attach to
33、thesame service delivery subsystem and the interfaces to the primary devices may or may not beSCSI. The number and arrangement of elements is arbitrary.Figure 2 - Example independent medium changer deviceThe independent changer model applies to implementations where the medium changer isaddressed as
34、 a separate logical unit. The logical unit for the medium changer may be accessedvia the same SCSI ID as the primary device, or via a different SCSI ID. This type of mediumchanger may support more than one primary device.The attached medium changer model permits a subset of the functions of an indep
35、endentchanger to be incorporated directly into a primary device. Only one data transport element ispermitted. In this case, only one logical unit is used to access all functions.A medium changer moves volumes among the several element types accessible to it oncommand from an initiator. Medium change
36、rs shall be capable of reporting the full or emptystatus of any element address in its domain.ANSI NCITS 314-1998115 Medium changer models5.1 Independent medium changerAn independent medium changer is a device server that returns 8h in the PERIPHERAL DEVICE TYPEfield (see SPC) of INQUIRY command res
37、ponse data.Independent medium changers for the SMC standard respond to a LUN different from those usedby a primary device. Communication with a primary device may use the same service deliverysubsystem as the medium changer device, or a different SCSI service delivery subsystem.Primary devices that
38、are not SCSI devices are also permitted. Multiple primary devices may beattached to an independent changer.If a primary device served by the medium changer is an SCSI device, the primary device may beaddressed on an SCSI-3 service delivery subsystem though the same port as the mediumchanger but with
39、 a different LUN or the primary device may be addressed through independentports and any LUN on the same or a different service delivery subsystem.The READ ELEMENT STATUS command response data page for each data transfer elementmay provide the identity of the primary device serviced by a medium chan
40、ger device. Thissupport is optional since a primary device is not required to be an SCSI-3 device.5.2 Attached medium changerAn attached medium changer is part of a device server that sets the MCHNGR bit to one in itsstandard INQUIRY data (see SPC). Attached medium changers respond to the same LUN a
41、s aprimary device that is not a medium changer. In an attached medium changer, the PERIPHERALDEVICE TYPE field of INQUIRY command response data returns the type of the primary device.Two medium changer commands, READ ELEMENT STATUS ATTACHED and MOVE MEDIUMATTACHED are added to the command set of the
42、 primary device. The other commandsavailable depend on the model for the primary device.5.3 Medium changer elementsA medium changer has an address space separate and distinct from the physical address spaceof an SCSI-3 service delivery subsystem. The term element is used throughout this standard tor
43、efer to one member of the medium changer address space. Within a medium changer, theelement addresses are a set of physical locations and mechanisms within the scope of a mediumchanger device.Each element is an instance of one of four element types: Medium Transport Element Storage Element Import/Ex
44、port Element Data Transfer ElementEach element is a discrete physical entity with a unique element address that may providestorage for zero or one volume. A volume is in exactly one element at a time. The point in timeduring movement when a volume is considered in a different element is implementati
45、ondependent. When requested to report element status, a volume shall be reported as being atexactly one element address. The element address shall not be arbitrarily changed by theANSI NCITS 314-199812medium changer. However, multiple initiator environments may cause volumes to be movedwithout notif
46、ying other initiators.Volumes are addressed indirectly by this model. Volumes can be moved to or from any of theelements of the medium changer device using element addresses. The method of detecting thepresence of a volume at any element in a medium changer is vendor specific.In order to ensure excl
47、usive access to a volume, the element where the volume is located (theelement address) may be reserved by an initiator. Exclusive access will be lost if the volume ismoved to an unreserved element. Exclusive access will be retained if a volume is moved betweentwo reserved elements. Reservation of th
48、e medium transport element used is not required topreserve exclusive access. In an independent medium changer, elements may be reserved bythe RESERVE ELEMENT (6), RESERVE ELEMENT (10), or PERSISTENT RESERVE OUT (seeSPC) commands. In an attached medium changer, element reservations are only available
49、using the PERSISTENT RESERVE OUT command.Providing independent storage for medium is optional for medium transport, import export, anddata transport elements. The capabilities of a particular medium changer can be determined frommode parameters in the device capabilities page (see 7.3.1).NOTE 1 - An example of an element not providing independent storage for a volume is a carousel stylestorage for volumes. The import/export function could be provided by a port which allows operator accessto one of the storage elements. In such a medium changer a MOVE MEDIUM command to move avolume fro
