1、AIIM MS59 lb LOI12348 D5008b BOT W I on Optical Digitd Data D ASSOCIATION FOR INFORMATION ANO IMAGE MANAGEMENT INTERNATIONAL 11 O0 Wayne Avenue Suite 11 O0 Silver Spring, Maryland 20910 AllM 301 -587-8202 COPYRIGHT Association for Information and with optical disk drives for different media sizes fr
2、om 90 mm to 356 mm media. Standard information about media errors allows end users and system integrators to retneve the same information even if their configurations consist of drives of different types, sizes, and manufacturers. This information can be retrieved using the same software, which can
3、be integrated into the media error information utilities or device drivers. The SCSI interface can be used instead of the high-level interface by using the selected set of SCSI-2 commands. This selected set of SCSI-2 commands allows systems integrators and end users to develop drive type and size in
4、dependent data verification tools at the SCSI level through the use of media error monitoring and reporting techniques. The use of a selected standard set of commands and approaches for media error monitoring i Association for Information and Image Management International COPYRIGHT Association for
5、Information that is, it can be used with systems that use write-once read many times (WORM), rewritable or partially read-only media ,and optical disk drives for all media sizes (e.g., 90 mm (3.5 inches) to 356 mm (14 inches). In addition, recognizing the importance and widespread use of the Small C
6、omputer System Interface (SCSI) in current generations of optical disk devices, this standard also defines an application of a selected set of SCSI-2 commands to provide media error monitoring and reporting techniques for verifying stored data on optical digital data disks. This standard also define
7、s a set of user requirements for monitoring and reporting media errors to verify stored data on optical digital data disks. The media error information that can be obtained using these tools includes the following: a list of reallocated sectors corrections that exceeded media error levels warning on
8、 verify media error levels total number of bytes in error, number of bytes in error per sector, and maximum number of bytes in error in any sector codeword the uncorrected or corrected sector content - errors encountered reading header information, such as the sector address, sector marks, and synch
9、ronization signals - maximum length of contiguous defective bytes per sector This standard covers optical digital data disks that use the following recording technologies: - WORM and MO-WORM (magneto-optic WORM) - rewritablehead-only This standard applies to both removable and non- removable optical
10、 disk media. Part of the information in this standard my be useful for CD-ROM subsystems, but implementations for that technology are beyond the scope of this standard. 1.2 Purpose The purpose of this standard is to provide users of information systems with standard media error monitoring and report
11、ing techniques for verifying stored data on optical digital data disks. These techniques provide media error information that allows users to - understand the status of data stored on optical disks - recover media error data of the desired level of sophistication, as directed by the system administr
12、ator - obtain error information that will highlight trends of the future, in particular selected disks or in their entire data sets - make decisions on how long the media can be used without an unacceptable risk of data loss - develop general cost-effective backup, recopying, and data transfer polic
13、ies after sufficient media have been analyzed The users or implementors will be able to - format optical digital data disks with or without certification - set media error level values for the optical disk drive - reallocate sectors whenever the media error levels are exceeded - set the verify media
14、 error level values to obtain early warning information about the status of the data In addition, the users or implementors will be able to obtain - the values of the set media error levels - the values of the verify media error levels - information about reallocated sectors - a defect list of initi
15、al media defects The users or implementors will have access to the media error log that gives information about the optical digital data disk error activity detected by the drive, and to either the corrected content or the uncorrected content of a 1 Association for Information and Image Management I
16、nternational COPYRIGHT Association for Information see ISOLEC 10089 Annex G). The bytes shall be expressed in hexadecimal values. The most recent data written to the addressed sector shall be read from the medium and returned. RDMED rADDR BXFER k0RR ON1 1 L L OFFJJ where: ADDR is the logical or phys
17、ical address of the sector that shall be transferred expressed as track and sector number (expressed in hexadecimal values); BXFER is the number of bytes that shall be read by the optical disk device and transferred to the host computer (expressed in hexadecimal values); CORR is the data corrected b
18、y the ECC. The default shall be to turn ECC correction ON. - ON: Causes data to be corrected by the ECC before being transferred to the host computer. - OFF: Causes uncorrected data to be transferred to the host computer. 6.2.5 Read Log Data (RLD) The RLD command shall be used to request that the op
19、tical disk device report log data to the host. Each parameter included with the command identifies a different log. The logs shall be returned to the host in the order that the log parameters are passed to the optical disk device. MEL is the MEDIA ERROR LOG; it provides detailed information about di
20、fferent media error indicators. The data in the MEL shall be sent to the host in the sequence defined in clause 7, table 22 of this standard. That is, Number of read retries shall be sent first, followed by Number or write retries, etc. Each parameter shall have a length of 6 bytes. This is the same
21、 parameter length specified for the same parameters in 7.12.3.2, Table 21, of this standard. The parameters shall be transferred as hexadecimal values. CLRMEL specifies that the MEL shall be cleared when read. The default shall be OFF. - ON: The MEL shall be cleared when it is read. - OFF: The MEL s
22、hall not be cleared when it is read. CMELL is the CURRENT MEDIA ERROR LEVELS LOG; it reports the current set Media Error Level values. These values shall be used by the optical disk device to 7 Association for Information and Image Management International COPYRIGHT Association for Information it re
23、ports the current set Verify Level Values. These levels shall be used by the optical disk device to provide an early warning to the host computer that the correction level exceeded the value for the related set level as defined in table 5, Verify Media Error Levels. The sector(s) that provoke the ea
24、rly warning can be found through the MEL. Table 5 shows the four specified Verify Media Error Level parameters. The data in the VCMELL shall be sent to the host in the sequence shown in table 5. Each parameter shall have a length of 6 bytes. This is the same parameter length specified for the same p
25、arameters in 7.12.2.2, Table 19 of this standard. The parameters shall be transferred as hexadecimal values. Verify maximum number of bytes in error per codeword per sector I Verify number of bytes in error per sector I I Verify number of bad IDS l 6.2.6 Set Media Error Levels (SMEL) The SMEL comman
26、d shall be used to set Media Error Levels that the optical disk device shall use for error recovery. The four Media Error Levels that can be set with this command are specified in table 4. The Media Error Levels are the same as those that are reported by CMELL using the IUD command. The Media Error
27、Levels shall be used for reallocating sectors. If the ECC level of correction exceeds one or more of the set levels and the parameters WR or RE in the DMERP command are ON, the sector shall be reallocated to a spare sector. If the parameters WR or RE in the DMERP command are OFF the optical disk dev
28、ice shall not reallocate the sector. In either case, the optical disk device shall report that a set level was exceeded, identify the level, and indicate whether the data were recovered or unrecovered. SMEL LBECW = ni LBES = n2 LID = n3 LMRS = n4 where nl to n4 are the level values (expressed in hex
29、adecimal) specified below: - LBECW: Level for Maximum Number of Bytes in Error per Codeword per Sector - LBES: Level for Number of Bytes in Error per Sector - LID: Level for Number of Bad IDS - LMRS: Level for Missing Resync 6.2.7 Set Verify Media Error Levels (SVMEL) The SVMEL command shall be used
30、 to set Verify Media Error Levels that the optical disk device shall use for error recovery. The four Verify Media Error Levels that can be set with this command are specified in table 5. The Verify Media Error Levels are the same as those that are reported by VCMELL using the RLD command. These lev
31、els shall be used for obtaining an early warning of media errors that exceeded any level set by this command. The optical disk device shall report that a set level was exceeded, identify the level, and indicate whether the data were recovered or unrecovered. SVMEL VLBECW = ni VLBES = n2 VLID = n3 VL
32、MRS = n41 Verify number missing resync* Table 5 - Verify Media Error Levels * Note: If the medium does not use resyncs, this level is NIA and the parameter shall be FFh. where nl to n4 are the level values (expressed in hexadecimal) specified below: - VLBECW: Verify Level for Maximum Number of Bytes
33、 in Error per Codeword per Sector - VLBES: Verify Level for Number of Bytes in Error per Sector 8 Association for Information and Image Management International COPYRIGHT Association for Information SDL is the acronym for Secondary Defect List. PDL and SDL, as well as the Plist and Glist bits are de
34、fined in ANSI X3.131 under the READ DEFECT DATA command (see 9.2.8 of ANSI X3.131). Plist Bit I I Transmitted Glist Bit ON I SDL 1 PDL first followed by ON 1 SDL* 1 Table 7 - Result of using the READ DEFECT DATA command * Note: For WORM media and devices, a Working Defect List (WDL) might exist. See
35、 both 7.7 in this standard (which describes the READ DEFECT DATA Command) and table 10, Defect descriptor 2 format (WW. It is recommended that users execute the READ DEFECT DATA command with the Glist and the Plist bits ON, immediately after certieing the media. When the SDL and the PDL exist on the
36、 media, they are part of the Disk Definition Structure (DDS). This structure is defined in the media standards (see 2 in this standard). In the case of alternative structures (such as other Defect Management Pointers or Sector Maps) when using the READ DEFECT DATA command with the Glist bit ON, the
37、data transferred to the initiator shall be the list of reallocated sectors and replaced sectors sent to the host computer in the format of a SDL (see 7.7 and table 9, Defect descriptor 1 format (SDL), of this standard). It is recommended that MODE SELECT parameters be set before executing the FORMAT
38、 UNIT command. Otherwise, the values recorded on the media will be used, if available. If these values are not on the media, the default values of the optical disk device will be used (to set the MODE SELECT parameters, see the manufacturers SCSI-2 programming manual for the appropriate optical disk
39、 device). Notes: 1. Defect descriptors shall be returned in either the block format or the physical format. The parameter shall be expressed in hexadecimal values. The Bytes from Index Format in tables 112 and 114 of ANSI X3.131 do not apply to this standard. 2. For implementations of this standard,
40、 bytes O to 2 in table 115 of ANSI X3.131 shall contain the parameter. “Track number of defect” (the track where the defect 10 Association for Information and Image Management International COPYRIGHT Association for Information z is usually equal to 1023 for a 1024 byte sector and equal to 51 1 for
41、a 512 byte sector. 14 Association for Information and Image Management International COPYRIGHT Association for Information however, they shall be in the same order as they occur on the media, according to any existing media interchange standard for the type of media used. For example, for IS0 10089
42、Format A media, the type of bytes shall be Data, DMP, CRC, and ECC; see IS0 10089 Annex G. The most recent data written to the addressed logical block shall be read from the media and returned. The bytes shall be expressed in hexadecimal values. 7.8.2.2 How to determine the defect length using the R
43、EAD LONG command Use the following procedure to determine the length of a defect in a sector: 1. 2. Compare the data obtained using the READ LONG command with error correction ON followed by the READ LONG command with error correction OFF. Analyze the contiguous bytes which are in error to tabulate
44、the defect length for any defect found in that sector. 7.9 The REQUEST SENSE command 7.9.1 Introduction In 8.2.14 of ANSI X3.131, the use of the REQUEST SENSE command is documented. That information shall be considered part of this standard. An additional requirement for the REQUEST SENSE command sp
45、ecified in this standard is that a CHECK CONDITION status returned because a Media Error Level or a Verify Media Error Level was exceeded shall set the ASCs and ASCQs (see 7.5.2 and 7.9.2 in this standard). 7.9.2 Requirements for media error monitoring and reporting 7.9.2.1 Media Error Levels and Ve
46、rify Media Error Levels If a Media Error Level is exceeded during reading or writing operations, the optical disk device shall return a CHECK CONDITION status with a sense key of Olh (RECOVERED ERROR) if the PER bit was set to ONE, or 03h (MEDIUM ERROR). The REQUEST SENSE command shall be used to re
47、trieve the ASCs and the ASCQs. (See table 11, table 12, and table 13.) If a Verify Media Error Level is exceeded during a VERIFY command or during the verify operation of a WRITE AND VERIFY, the optical disk device shall return a CHECK CONDITION status with a sense key of 03h (MEDIUM ERROR). The REQ
48、UEST SENSE command shall be used to retrieve the ASCs and the ASCQs (see table 14, Sense codes used when a Verify Media Error Level is exceeded). 15 Association for Information and Image Management International COPYRIGHT Association for Information & Imaging ManagementLicensed by Information Handli
49、ng Services AIIM MS59 96 E LO12348 0500889 bT8 ANSVAIIM MS59-1996 Media Error Monitoring and Reporting Techniques for Verification of Stored Data on Optical Digital Data Disks Maximum bytes in error per codeword per sector - when writing - when reading ID Sense ASC ASCQ Description Key 3 OCh 02h Write Error - Auto Reallocation Failed 3 Ilh 04h Unrecovered Read Error - Auto Reallocate Failed 3 loh OOh ID CRC or ECC Error Resvnc I 3 I llh I 07h I DataResvnchronizationError I Maximum bytes in error per codeword per sector - when writing - whenreading ID Resync Table 12 - Sen
