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Summary of Contents for PYTHON 4322

Page 1: ...PYTHONTM DDS DC DATA COMPRESSION DAT TAPE DRIVES Model 4322 3 50 lnch Internal Tape Drive 4542 5 25 lnch Internal Tape Drive 4352 External Subsystem PRODUCT DESCRIPTION MANUAL January 1992 ARc CORPO J E ...

Page 2: ...DDS DC DATA COMPRESSION DAT DRIVES 4322 3 5 lnch Internal Tape Drive 4542 5 25 lnch Internal Tape Drive 4352 External Subsystem PRODUCT DESCRIPTION MANUAL v 6 COfJft ARCHIVE CORPORATION 1650 Sunflower Avenue Costa Mesa CA 92626 714 641 1230 FAX 714 641 2590 January 1992 ...

Page 3: ...1991 and 1992 Archive Corporation All rights reserved No part of this publication may be reproduced stored in a retrieval system or transmitted in any form or by any means electronic mechanical photocopying recording or otherwise without prior written permission from Archive Corporation Archive Python and QICstream are trademarks of Archive Corporation Product features and specifications described...

Page 4: ...3 2 Guidelines and Cautions 4322 and 4542 Internal Models 3 3 Unpacking and Inspection 3 4 Cabling and Connectors 3 4 1 Cabling Considerations 3 4 2 Electrical Characteristics 3 4 3 Single Ended SCSI Connector Internal Models 4322 and 4542 3 4 4 Single Ended SCSI Connector Model 4352 3 5 Installing the Python 4322 and 4542 Internal Drives 3 5 1 Setting Operational Switches 3 5 2 Mounting the Drive...

Page 5: ...alities Between the Formats 6 2 Entities DDS DC Format Only 6 3 Tape Layout 6 4 Single Data Space Layout 6 4 1 Device Area 6 4 2 Reference and System Area 6 4 3 Data Area 6 4 4 End of Data EOD Area 6 5 Two Partition Layout 6 6 Data Storage Organization 6 7 Individual Track Layout 6 7 1 Main Area 6 7 2 Subareas 6 8 Group Structure 6 8 1 Data Frames 6 8 2 Index 6 8 3 ECC Frame 6 8 4 Amble Frames 6 9...

Page 6: ...ndix B Acronyms and Measurements B 1 Abbreviations and Acronyms B 2 Measurements Appendix C Data Compression SCSI Information C 1 Introduction C 2 MODE SELECT Page C 2 1 Compression Control Byte 02 C 2 2 Decompression Control Byte 03 C 3 MODE SENSE Page C 3 1 Compression Control Byte 02 C 3 2 Decompression Control Byte 03 C 3 3 Compression Algorithm Byte 07 C 3 4 Decompression Algorithm Byte 11 C ...

Page 7: ...anel Figure 4 2 Python 4542 Front Panel Figure 4 3 Python 4352 Front Panel Figure 4 4 Cassette Loading 4322 OAT Drive Figure 4 5 Manually Removing a Cassette Python 4322 Drive Figure 4 6 Manually Removing a Cassette Python 4542 Drive Figure 4 7 Manually Removing a Cassette Python 4352 Drive Figure 6 1 Single Data space Tape Layout Figure 6 2 Reference and System Area Layout Figure 6 3 Two Partitio...

Page 8: ...able 5 1 Status Codes SCSI l Table 5 2 Message Codes SCSI 1 Table 5 3 Commands SCSI l Table 5 4 Status Codes SCSI 2 Table 5 5 Message Codes SCSI 2 Table 5 6 Commands SCSI 2 Table 6 1 Bit configurations of Flag Byte DDS DC Fonnat Only Table 7 1 Simplified Compression Table 7 2 Simplified Decompression Table 7 3 Dictionary Table 8 1 Tape Lengths and Capacities Table 9 1 Reliability Specifications 8 ...

Page 9: ...git model designation 4322 for example refers to all of the 4 digit 2 letter models included in that model designation For example 4322 refers to the 4322NT and 4322NP models This document gives you an in depth look at the Python 4322 4542 and 4352 DDS DC drives It is intended for those familiar with basic tape drive technology or who are using or evaluating Python DAT data compression drives This...

Page 10: ...he DDS format These Python drives use an advanced DCLZ data compression LempelZiv algorithm to compress data by up to four or more times More importantly however DDS DC data compression is transparent to the host software and SCSI driver enabling rapid integration and preserving existing software investments Because the DDS DC format is a superset of the DDS format the Python data compression driv...

Page 11: ...ne major benefit of this new computer grade engineering is low power consumption typically below 7 Watts All Python DDS DC drives contain an embedded SCSI controller that supports SCSI 1 ANSI X3 131 1986 and SCSI 2 ANSI X3T9 2 Working Draft Revision 10 The 3 5 inch and 5 25 inch internal drive form factors are tailored for easy installation in today s computers and the full featured embedded SCSI ...

Page 12: ... PIN 259n Oxx PIN 27264 Oxx PIN 27402 Oxx PIN 27373 Oxx PIN 27265 Oxx 1024 KB PIN 25977 5xx PIN 27264 5xx PIN 27402 5xx PIN 27373 5xx PIN 27265 5xx Form Factor 3 50 H H 3 50 H H 5 25 H H 1 5 25 H H 1 External Subsystem Mounting Internal Internal Internal Internal External SCSI Single Ended Single Ended Single Ended Single Ended Single Ended Data Compression Yes Yes Yes Yes Yes Conventional EEPROM ...

Page 13: ...0 for single ended SCSI interface models without data compression 1 for differential SCSI interface models without data compression and 2 for single ended SCSI interface models with data compression Position 5 also shows whether the drive is an internal or external unit This character is an N for internal or an X for external Position 6 shows the interface and PROM type For the SCSI l or SCSI 2 co...

Page 14: ...Figure 1 2 Python 4542 DAT Drive Figure 1 3 Python 4352 DAT Drive 1 5 INTRODUCTION ...

Page 15: ...maximum capacity of 8 GB on a 90 meter DDS cassette o High speed random access of 20 seconds average to any file on a 60 m tape 30 seconds for a 90 m tape o High speed transfer rates for fast backups 183 KB sec 11 MB min uncompressed data 366 KB sec 22 MB min typical compressed data 732 KB sec 44 MB min nominal maximum compressed data o High performance SCSI burst transfer rate of S MB sec with up...

Page 16: ...refer to host adapters or peripheral devices such as printers magnetic disks or tape drives The eight devices or hosts are daisy chained together Figure 1 4 shows sample configurations of SCSI systems COMPUTER HOST SCSI BUS PYTHON SYSTEM ADAPTER DRIVE SINGLE INITIATOR SINGLE TARGET COMPUTER HOST SCSI BUS PYTHON SYSTEM ADAPTER JIll DRIVE SINGLE INITIATOR SINGLE TARGET MAGNETlC DISK JIll PRINTER or ...

Page 17: ...ocated on a rapidly rotating cylinder or drum The cylinder is tilted at an angle in relation to the vertical axis of the tape As the tape moves horizontally it wraps around the part of the circumference of the cylinder 900 so that the head enters at one edge of the tape and exits at the other edge before the tape unwraps The horizontal movement of the tape in combination with the angular movement ...

Page 18: ...d records A recorded OAT cassette may contain compressed records uncompressed records filemarks and setmarks Compressed records exist within recorded objects called entities Entities and uncompressed records are collected into groups Many aspects of the DDS DC format are identical to those of the DDS format o The series of transformations randomizing interleaving generation and inclusion of two Re...

Page 19: ...rive because many new techniques such as increasing the capacity of the drive through support for ionger tapes may require only a firmware upgrade 1 6 Software One of the most cost effective uses of DAT drives is to back up fixed disks The software required to perform a disk backup runs under the control of the host computer s operating system Compatibility with a wide range of software is also an...

Page 20: ...the DDS DC tape formats Describes the data compression algorithm and explains pertinent information for effective use of data compression Details the functional operation of various assemblies of the Python DDS DC drives Presents maintenance procedures and reliability information AppA Glossary Defines key terms App8 Acronyms and Measurements AppC Data Compression SCSI Information Lists the acronym...

Page 21: ...ARCHIVE PYTHON DDS DC DAT DRIVES PRODUCT DESCRIPTION MANUAL NOTES 1 12 ...

Page 22: ...gulatory compliance o ANSI Conformance Statements SCSI l and SCSI 2 2 2 Physical Specifications The physical specifications of Python drives are listed in Table 2 1 NOTE Installation operation and most technical information for the 4322NT and 4322NP drives is the same In this guide the model designation 4322 is used to refer to both drives Likewise installation operation and most technical informa...

Page 23: ... Height 1 6 in 41 mm 1 6 in 41 mm 3 4 in 85 mm Width 4 0 in 101 mm 5 7 in 146 mm 5 3 in 135 mm Length 6 0 in 152 mm 7 1 in 180 mm 9 3 in 235 mm Weight 2 0 Ibs 0 9 kg 2 4 Ibs 1 1 kg 5 2 Ibs 2 4 kg Figure 2 1 illustrates the Python 4322 drive showing its general dimensions 4 2 I I11 Figure 2 1 Python 4322 Computer OAT Drive General Dimensions 2 2 ...

Page 24: ...11 Drive Busy AMBER Figure 2 2 Python 4542 Computer OAT Drive General Dimensions Figure 2 3 illustrates the Python 4352 subsystem showing its general dimensions DRIVE BUS AMBER v CASSETIE IN PLAC GREEN POWER ON GREEN E i v I I I I C t3 4 1 Figure 2 3 Python 4352 External Subsystem General Dimensions 2 3 SPECIFICATlONS ...

Page 25: ...r and are nominal values Table 2 2 Power Specifications for the Python 4322 and 4542 Drives SPECIFICATION DC Voltage Voltage Tolerance Operational Current Standby Current Peak Power Sequence Ripple peak to peak Power Dissipation Operating MEASUREMENT 12 VDC or 10 210 milliamps 210 milliarnps 1 40 amps None 100 mV 5 0 Watts excluding surge 2 4 5VDC or 7 900 milliamps 700 milliamps 1 30 amps None 10...

Page 26: ...352 external drives have a built in power supply that senses the incoming voltage and automatically adapts to voltages within the range of 100 to 240 volts 50 to 60 Hz Table 2 4 lists its power specifications Table 2 4 Power Specifications for the Python 4352 Drives SPECIFICATION AC INPUT VOLTAGE 100 Japan 120 US 240 European AC Input Current 230 milliamps 200 milliamps 125 milliamps AC Input Powe...

Page 27: ...eed SPECIFICATlON 2 6 gigabytes on a 60 meter OAT cassette typical 5 2 gigabytes on a 60 meter OAT cassette maximum1 4 0 gigabytes on a 90 meter OAT cassette typical 8 0 gigabytes on a 90 meter OAT cassette maximum1 61 000 brts Inch 76 250 flux transferslinch 1 869 trackslinch 114 Megabits square inch Read after write Reed Solomon ECC C3 3 levels Less than 1 in 1015 data bits Computer grade 4 Dire...

Page 28: ...o condensation 300 to 15 250 meters 1 5 9 5 to 500 Hz Vibration peak acceleration Sweep rate less than 1 octave minute Acoustic level Idling Acoustic level Operational Shock 1 2 sine wave 1 Mechanism and media 2 Mechanism 49 dBA maximum 53 dBA maximum measured in suitable endosure at 3 ft distance and operator height 10 g s peak 11 msec 2 6 OAT Cassette Specifications 50 g s peak 11 msec Python DD...

Page 29: ...The Python DDS DC drives also conform to the following safety standards o UL 1950 Information Technology Equipment Including Electrical Business Equipment First Edition o CSA C22 2 No 950 M89 Safety of Information Technology Equipment Including Electrical Business Equipment First Edition All Python internal drives external drives pending o EN 60 950 Safety ofInformation Technology Equipment Includ...

Page 30: ...he external subsystem 3 2 Guidelines and Cautions 4322 and 4542 Internal Models The following guidelines and cautions apply to handling and installing Python 4322 and 4542 internal drives Keep them in mind as you install the drive o Because Python internal drives contain components that are sensitive to static electricity the drives are shipped in a protective anti static bag DO NOT remove the dri...

Page 31: ...abling and connectors for the 4322 4542 and 4352 drives Refer to Sections 3 5 and 3 6 for actual installation instructions 3 4 1 Cabling Considerations Either 50 pin flat cable or 25 signal twisted pair cable with a maximum length of 6 meters 19 feet may be used to connect the Python drives to the SCSI host adapter output If twisted pair cabling is used connect the twisted pairs to physically oppo...

Page 32: ...ese conditions may be met by any valid configuration of targets and initiators All signals use open collector drivers The output characteristics measured at the connector of the drive of signals driven by the Python drive are o Signal assertion low level output voltage 0 0 to 0 5 VDC at 48 milliamps sinking o Signal negation high level output voltage 2 5 to 5 25 VDC Signals received by the Python ...

Page 33: ...ator power is enabled 2 ANSI defines RST as a bidirectional pin On the Python drive RST is input only 3 4 4 Single Ended SCSI Connector Model 4352 The Python 4352 external drive provides two 50 pin shielded connectors ANSI Alternative 2 on the rear panel of the drive These connectors consist of two rows of ribbon contacts spaced 2 16 mm 0 085 in apart These two connectors facilitate adding the dri...

Page 34: ...3 5 inch drive that mounts internal to the computer in a 3 5 inch half high space The Python 4542 is a 3 5 inch drive with mounting rails and bezel for internal installation in a 5 25 inch half high space Installing these two drives consists of a few easy steps 1 Set operational switches Section 3 5 1 2 Mount the drive unit Section 3 5 2 3 Complete the power and interface connections Section 3 5 3...

Page 35: ...efore you install the 4322 or 4542 drive in the computer set the eight position switch bank mounted on the PCB at the rear of the drive Figure 3 1 illustrates the switchbank location for the 4322 drive TERMINATORS PIN 1 SERIAL PORT Figure 3 1 Python 4322 Switchbank Access 3 6 DATA COMPRESSION CHIP ...

Page 36: ...wer up S4 Default SCSI 2 S4 ON o Parity check enable disable S5 Default Parity disabled S5 OFF o DDS pass through mode enable disable S6 Default Pass through mode disabled S6 OFF NOTE WhenS6 is OFF DDS DC data compression is enabled WhenS6 is ON DDS DC data compression is disabled o Power on self test enable disable S8 Default Power on self test disabled S8 OFF NOTE Switch S7 is reserved and must ...

Page 37: ...o take effect or a SCSI Bus Reset must be received If the default settings are correct for your system go to Section 3 5 2 DDS DC data compression enabled S6 OFF is also set as a factory default If you need to change any defauit settings refer to the appropriate following section make the changes and then go to Section 3 5 2 SCSI Device Address S1 through S3 The three switches Sl through S3 corres...

Page 38: ...INSTALLATlON SCSI Device Address S3 S2 S1 OFF 0 ON OFF ON OFF 2 ON OFF 3 ON OFF 4 ON OFF 5 ON OFF 6 ON OFF 7 ON Figure 3 4 SCSI Device Address Selection 4322 and 4542 3 9 ...

Page 39: ...gh mode S6 OFF disables DDS pass through mode NOTES When S6 is OFF DDS DC data compression is enabled during writing When S6 is ON DDS DC data compression is disabled When reading DDS DC compressed data is always decompressed regardless ofthe position ofS6 The function ofthe S6 switch can be over ridden by the proper SCSI MODE SELECT command issued from the host computer Regardless ofthe position ...

Page 40: ...ver the two pins See Figure 3 1 for the 4322 drive and Figure 3 2 for the 4542 drive Be sure it is firmly in place CAUTION Ifthe jumper is installed be careful not to short the TERMPWR signal to ground The terminator power fuse is located beside the terminator power jumper to prevent damage to drive components in case the terminator power is shorted If terminator power is enabled and the SCSI cabl...

Page 41: ...over the two verticalpins for each switch required To turn S1 S2 or S3 OFF remove the jumper shunt from the two verticalpins for each switch required Set the DIP switches S1 S2 and S3 all to OFF to use the external SCSI address port 3 5 2 Mounting the Drive Unit The Python 4322 and 4542 internal drives can be installed in three different orientations one horizontally eject button right and two ver...

Page 42: ...m 1 18 in 2 PLACES II II II 59 9mm 2 36 in 2 PLACES f II I I l I 20 mm 82 in 2 PLACES Side 151 2 mm 5 96 in INSTALLATION 101 2 mm 3 98 in I 1r 3 6mm 14 in 2 PLACES I mm I 1 011 3 70 in I r IIIII w I I 8 I J M3 0X I I I 4 DEEP MIN 4 PLACES I 70 1 mm I I 2 76 in I I III III I I III III I III 31 0 mm III I 103 7 mm 4 08 in Bottom Figure 3 6 Mounting Hole Locations 4322 3 13 ...

Page 43: ...CES 1 5 5mm 2 PLACES I 22 in 79 4 mm 3 13 in 2 PLACES I I _ ___LI I_LI___II 1 I III I I 4 D IN I I I I I I 4 PLACES I I 79 4mmJ I I 3 13 in I I I I 4 t I II iI 7 6 mm 87 3 mm 30 in 3 44 in 2 PLACES 2 PLACES 47 6mm 1 87 in 2 PLACES t 4 I 41 4 mm l r 1 63in T 5 8mm 23 in Side 2 PLACES I I 47 6 mm III e I 1 87 in e I 149 1 mm I __ 5 87 in Bottom Figure 3 7 Mounting Hole Locations 4542 3 14 ...

Page 44: ...the cable to Pin 1 on the drive Failure to do so could make the Python drive inoperative o The recommended power mating connector requires an AMP 1 48024 0 housing with AMP 60617 1 pins or equivalent o The mating interface connector for 4322 and 4542 drives is a single ended connector as described in Section 3 4 with pin assignments as listed in Table 3 1 When you make the connection be sure pin 1...

Page 45: ...ric Python 4352 external drives are set by default at the factory for o SCSI 2 as the power on interface o Parity disabled o Power on self test disabled o Terminator power is supplied to the SCSI bus o DDS pass through mode disabled data compression ON NOTE Generalpurpose default settings shown previously in Figure 3 3 also apply to the Model 4352 Installing these drives consists of a few easy ste...

Page 46: ...ndow Turn the unit power OFF then ON 3 6 2 Completing the Interface Connection The Python 4352 drive provides two SCSI connectors to allow daisy chaining See Figure 3 10 Either connector can connect to the host computer or any SCSI device in a daisy chain NOTE Turn offallpower before connecting cables and the terminator o When the Python drive is the last drive in the chain a single interface cabl...

Page 47: ...er of the daisy chain connections The mating interface connector for Model 4352 is a single ended connector as described in Section 3 4 with pin assignments as listed in Table 3 2 3 6 3 Connecting the Power Cord See Figure 3 10 for the location of the power cord connector Insert the power cord mating connector into the connector on the rear panel Be sure the connection is secure Plug the other end...

Page 48: ...efficiently often at a ratio of 4 1 or more Data with little redundancy such as executable programs can be compressed least A unique feature of the Python DDS DC drives is expansion minimization To provide this feature the drive continuously monitors the compression ratio If the compressed version becomes larger than the original version data compression would be automatically turned OFF Although ...

Page 49: ...and switch 8 is ON the power on self test may have failed In that case the drive will not operate NOTE Some guidelines for operation in high humidity conditions are listed in Chapter 9 The green rectangular Cassette Status LED indicates the following conditions o When ON lit a cassette is inserted and does NOT generate excess errors o When flashing slowly a cassette is inserted but generates exces...

Page 50: ...the 4322 4542 and 4352 drives respectively Cassette Insertion Slot Eject Button Drive Busy AMBER Figure 4 1 Python 4322 Front Panel Cassette Insertion Slot I I 1 1 I I I I r Cassette in Place GREEN Eject Button Drive Busy AMBER Figure 4 2 Python 4542 Front Panel 4 3 ...

Page 51: ...d 4352 ONLY Table 4 1 LED Summary ACTION ON lit Flashing Rapidly ON lit Flashing Slowly Flashing Slowly with amber LED flashing Flashing Rapidly ON lit 4 4 MEANING The drive is reading or writing the tape A hardware fault occurred or dew was detected A cassette is inserted and does NOT generate excess errors A cassette is inserted but generates excessive errors beyond a predefined error threshold ...

Page 52: ...g until it is fully recessed into the cassette insertion slot Insert the cassette with the arrow on the top of the cassette entering the slot first Figure 4 4 illustrates cassette loading 4322 internal drive shown Figure 4 4 Cassette Loading 4322 OAT Drive You unload the cassette by pressing the eject tape unloading button on the front panel See Figures 4 1 4 2 and 4 3 of the front panels for the ...

Page 53: ...computer For the 4352 remove the power cord from the drive 3 For internal drives remove the drive from the computer For the 4352 drive turn the unit upside down and remove the four screws two screws on each side that attach the drive cover to the chassis unit Remove the drive cover and retain the screws Figure 4 5 shows the Python 4322 3 5 inch drive with the cover removed Figure 4 6 shows the Pyt...

Page 54: ...REAR CASSETTE GEAR FRONT ROLLER Figure 4 5 Manually Removing a Cassette Python 4322 Drive 4 7 DRIVE OPERATlON MODE MOTOR SHAFT ...

Page 55: ...ARCHIVE PYTHON DDS DC OAT DRIVES PRODUCT DESCRIPTION MANUAL REAR CASSETIE GEAR Figure 4 6 FRONT ROLLER Manually Removing a Cassette Python 4542 Drive 4 8 MODE MOTOR SHAFT ...

Page 56: ...it is automatically initialized The Python drive first detects that the tape is blank about 10 12 seconds It then initializes the tape when it receives a command that causes writing to the tape NOTE Initializing the tape takes about 30 seconds Ejecting the cassette before the initialization is completed causes theprocedure to abort The initialization than restarts from the beginning the next time ...

Page 57: ... tape unload button on the front panel to remove the cassette The Python buffer is then emptied to tape and the tape is rewound The Python s data buffer is also emptied to the tape in these three cases o A REWIND command is issued o The eject button is pushed o A delay as defined by MODE SELECT or the one minute default delay time in which no activity occurs Before the Python drive ejects the cass...

Page 58: ...ware upgrade cassette is inserted in the drive it is important that no power interruption occurs while the firmware is loading DO NOTPOWER OFF THE DRIVE AT THIS TIME If apower interruption occurs the firmware may not be loaded correctly and the drive may not operateproperly If a problem occurs during the firmware loading process the cassette is ejected and the amber LED on the front panel flashes ...

Page 59: ...ARCHIVE PYTHON DDS DC OAT DRIVES PRODUCT DESCRIPTION MANUAL NOTES 4 12 ...

Page 60: ...thon 4322 4542 and 4352 drives provide a single ended SCSI connection This chapter summarizes the SCSI 1 and SCSI 2 status codes message codes and commands Refer to Chapter 3 for specific SCSI cabling and connector infonnation NOTE Refer to the Python Technical Reference Manual PIN 25356 002 DDS only or to the Python SCSI Manual PIN 27298 001 available in 1992 for detailed information about the SC...

Page 61: ...ected Error Out OSh Abort Out 07h Message Reject In Out 08h No Operation Out OAh Linked Command Complete In OBh Linked Command Complete with Flag In OCh Bus Device Reset Out 80h Identify No Disconnect Reconnect In Out COh Identify Disconnect Reconnect In Out 01h Extended Message In Out Direction In Drive to host Out Host to Drive Supports only one extended message SYNCHRONOUS DATA TRANSFER REQUEST...

Page 62: ...Ch V SEEK BLOCK 10h M WRITE FILEMARKS 11 h 0 SPACE 12h E INQUIRY 13h 0 VERIFY 14h 0 RECOVER BUFFERED DATA 15h 0 MODE SELECT 16h 0 RESERVE UNIT 17h 0 RELEASE UNIT 19h 0 ERASE 1Ah 0 MODE SENSE 1Bh 0 LOAD UNLOAD 1Dh 0 SEND DIAGNOSTIC 1Eh 0 PREVENT ALLOW MEDIUM REMOVAL 40h CHANGE DEFINITION M Mandatory Command o Optional Command E Extended Command V Vendor Unique Command Defined in SCSI 2 5 3 ...

Page 63: ...filemarks and EOD 11 Supports third party reservation 1 Change Definition 2 Erase 3 Inquiry 4 Load Unload 5 Mode Select 6 Mode Sense 7 Prevent Allow Media Removal 8 Read 9 Read Block Limits 10 Recover Buffered Data 11 Release Unit 12 Request Block Address 1 Save Data Pointer 2 Disconnect 3 Message Reject 4 Identify 5 Abort 6 Bus Device Reset 7 No Operation 8 Bus Device Reset 1 Seek Block 5 4 14 Re...

Page 64: ...rmediate Status 0 0 X Reservation Conflict Table 5 5 Message Codes SCSI 2 CODE DESCRIPTION DIRECTlON OOh Command Complete In 02h Save Data Pointer In 04h Disconnect In OSh Initiator Detected Error Out 06h Abort Out 07h Message Reject In Out 08h No Operation Out OAh Linked Command Complete In OBh Linked Command Complete with Flag In OCh Bus Device Reset Out 80h Identify No Disconnect Reconnect In O...

Page 65: ...SPACE 12h M INQUIRY 13h 0 VERIFY 14h 0 RECOVER BUFFERED DATA 15h M MODE SELECT 16h M RESERVE UNIT 17h M RELEASE UNIT 19h M ERASE 1Ah M MODE SENSE 4ML 1011 0 LOAD UNLOAD 1Ch 0 RECEIVE DIAGNOSTIC RESULTS 1Dh M SEND DIAGNOSTIC 1Eh 0 PREVENT ALLOW MEDIUM REMOVAL 2Bh 0 LOCATE 34h 0 READ POSITION 3Bh 0 WRITE DATA BUFFER 3Ch 0 READ DATA BUFFER 40h 0 CHANGE DEFINITION 4Ch 0 LOG SELECT 4Dh 0 LOG SENSE M Ma...

Page 66: ...nd report operation of data compression in sequential access devices 1 Change Definition 2 Erase 3 Inquiry 4 LoadlUnload 5 Locate 6 Log Select 7 Log Sense 8 Mode Select 9 Mode Sense 10 Prevent Allow Media Removal 11 Read 12 Read Block Limits 13 Read Data Buffer 14 Read Position 15 Receive Diagnostic Results 1 Save Data Pointer 2 Disconnect 3 Message Reject 4 Identify 5 Abort 6 Bus Device Reset 7 N...

Page 67: ...ARCHIVE PYTHON DDS DC OAT DRIVES PRODUCT DESCRIPTION MANUAL NOTES 5 8 ...

Page 68: ...ion in Python drives uses the advanced DCLZ data compression LempelZiv algorithm The industry standard DDS DC format has been approved by the DDS Manufacturers Group ANSI and ECMA 6 1 1 DDS Format The DDS format supports OAT devices as computer peripherals The objectives of the DDS format are o To maximize storage capacity and perfonnance o To facilitate data interchange o To provide compatibility...

Page 69: ...lities o Enables a tape drive without decompression capabilities to retrieve compressed data and transmit it to the host for decompression o Maintains high performance by the compression algorithm while avoiding controller induced limitations of the transfer rate when handling multiple small fixed length records o Allows writing of compressed and uncompressed records to the same cassette In the DD...

Page 70: ... a decompression algorithm must start whether or not the required data is at the beginning of the sequence Thus the access point mayor may not exist at the start of the first compressed record in the entity however access points cannot appear elsewhere in an entity Access points are required in certain cases and are important when performing SCSI SEEK or LOCATE commands to a record within a entity...

Page 71: ...p having a fixed capacity The single data space provides a capability similar to 1 2 inch reel to reel tape It allows for sequential storage and access to data and separator marks in a continuous space which spans the entire tape volume The two partition layout gives the same capability in each of two independent partitions on the tape Data may be written to either partition without affecting the ...

Page 72: ...from the Beginning of Media BaM is attained a device area is provided The content of this area is not defined by the DDS format Immediately following the device area is another area that contains no valid signals recorded on it This area is a guard zone between the test area and the start of recorded frames 6 4 2 Reference and System Area The second area on this tape layout is the Reference and Sy...

Page 73: ... The System area consists of o The System Preamble which allows the servo to synchronize before reading the System Log o The Tape Log which contains tape usage infonnation including current usage error count The Tape Log in this format contains information for the entire tape o The System Postamble which consists of ten frames Immediately following these frames is another band of ten identical fra...

Page 74: ...herefore contain more than one EOD area However the EOD closest to the BOT is the only valid one Any data or other EOD areas beyond that point are logically inaccessible 6 5 Two Partition Layout The two partition tape layout provides two separate areas that may be written independently to be contained on a single tape volume The host chooses the tape layout single data space or two partition befor...

Page 75: ... location of data records filemarks and save set marks The data area on the tape is organized into groups Each group is made up of a fixed number of frames and has a fixed capacity A group stores host written data save set marks and fllemarks In the DDS format the host written data consists of uncompressed records in the DDS DC format the host written information may consist of uncompressed record...

Page 76: ...e up of the following o Synchronization 8 bits o Main ID 16 bits WI and W2 o Main ID parity 8 bits o Main data 256 bits Synchronization Pattern The 10 channel bit synchronization pattern corresponds to 8 bits which are contained in the synchronization portion of the main data block Main ID The Main ID is made up of WI 8 bits and W2 8 bits These bits identify various characteristics about the main ...

Page 77: ... symbols of Cl parity The main data area is made up of o The header first four bytes which contains format information o 5756 bytes of user data o 64 bytes of zeros The header contains the Data Format ID DFID for the tape with 0000 indicating the DDS format The Logical Frame ID LF ID contains the logical frame number bits 8 13 the ECC frame ID bit 14 and the last frame ID bit 15 If bit 14 the ECC ...

Page 78: ...C retries 6 8 Group Structure A group is made up of 22 data frames for a size of 126632 bytes and an optional ECC frame Groups are separated by zero or more amble frames The 22 data frames contain host written data and index information Figure 6 5 shows the group structure ECC FRAME ERROR CORRECTION CODE I_ ONE GROUP I 22 DATA FRAMES APPROXIMATELY 128 KBYTES Figure 6 5 Group Structure Figure 6 6 c...

Page 79: ...through 126632 A Block Access Table BAT is located immediately before the GIT The first 4 byte entry of the BAT occupies bytes 126597 through 12660 with additional BAT entries extending toward the front of the group If necessary records are split as needed to fill a group complete with data and index information A group that is not filled with user data contains an index specifying that it is not ...

Page 80: ...counters and pointers that describe the characteristics of the group For the DDS DC format the defInitions of three of the fIelds in the GIT are extended 6 9 1 Group Information Table GIl The GIT is included in each group It is in a fIxed location at the end of the group and is the same size regardless of the contents of the group bytes 126601 through 126632 It contains a list of counters and poin...

Page 81: ...xists o The number of Total Count of Entity entries contained in the BAT of the current group Previous Record Group Count The Previous Record Group Count is the number of the group containing the most recent beginning of record For the DDS DC format this 2 byte field specifies the running number of the highest numbered previous group that contains the beginning of an uncompressed record an access ...

Page 82: ... The entity starts in a previous group and ends in the current group Last Part of Entity The count field specifies how many bytes are contained in the part of the entity that is in the current group An entry for the Total Count of Entity must follow this entry in the BAT of the current group This entry Total Count of Entity follows an entry for the Last Part of Entity in the BAT The count field sp...

Page 83: ...Read After Write RAW technique provides a means of verifying that host data was written on the tape correctly by reading it later After each frame is written it is examined to determine whether or not it is correctly recorded If a frame is identified as bad it is rewritten later down the tape The bad frame is not necessarily rewritten immediately It can be rewritten after three four or five other ...

Page 84: ...e strings Because these smaller symbols are substituted for the longer strings of data more data can be stored in the same physical space Some important benefits result from data compression in DAT drives D The same amount of information can be stored on a smaller length of tape D More data can be stored on a given length of tape D Performance can more closely parallel that of high transfer rate c...

Page 85: ...ression method can be tailored to achieve maximum speed and storage for that type However an effective data compression method for a tape drive must serve varying data types while ensuring maximum storage and transfer rates as well as maintaining data integrity Thus creating an effective data compression method with those stipulations requires integrating several design decisions that work togethe...

Page 86: ... in addition to its regular computations Also any other host that wants to retrieve decompress the data must have the same software resident The AHA3101 data compression chip is designed to facilitate a complete data compression system using the DCLZ algorithm This chip provides support circuitry as well as the core DCLZ machine Refer to Section 7 3 for a more detailed description of the data comp...

Page 87: ...aced in the data stream by its numeric value codeword 7 2 1 Simplified Compression Operation The following steps describe a simplified version of operation of the algorithm for compressing data 1 From the current position in the input data stream the algorithm fetches bytes characters until a string is formed that does not have a matching entry in the dictionary 2 The codeword for the longest stri...

Page 88: ... encoded bytes represent single bytes of the input data stream and contain the values 0 through 255 o Dictionary codes codewords 264 through 4095 The dictionary codes refer to dictionary entries and represent multiple bytes a string of characters in the input data stream These codes are built as the input steam is processed These codes are pointers to other locations and eventually end by pointing...

Page 89: ...roper order The following steps describe a simplified version of the operation of the algorithm for decompressing data 1 From a reset dictionary point which contains only control codes and encoded bytes codewords are fetched from the input stream and looked up in the dictionary 2 New dictionary codes are built by combining the previously received codewords Thus the dictionary created during compre...

Page 90: ...ssion circuitry which forms the core of the data compression system by implementing the DCLZ algorithm This core is called the DCLZ machine In addition to the DCLZ machine this data compression chip provides support circuitry in the form of four main interfaces o The processor interface allows a microprocessor to access information inside the chip and in the SRAM buffer o The Port A and Port B DMA...

Page 91: ... data to and from the main data buffer of the drive The data flow through the AHA3101 data compression system for compression is generally as follows 1 During compression the input data stream flows into an SRAM data buffer through the Port A DMA interface 2 From the SRAM buffer the input data stream uncompressed data then flows to the DCLZ machine In the DCLZ machine the data is compressed and th...

Page 92: ...efits of the helical scan recording method namely 1 high density recording all tape space is utilized by dense overlapping tracks at alternating azimuth angles and 2 high speed searches o Using second generation audio and custom LSIs for efficient circuit layout and increased reliability with low power consumption These LSIs are quad flat pack QFP designs using complementary metal oxide semiconduc...

Page 93: ...T Drives This section generally describes the hardware design features of the Python data compression drives You may want to refer to the block diagrams referenced in Section 8 2 as you read this infonnation Python computer OAT drives use the helical scan recording method employing a four head design Four direct drive motors and one brush type motor are used in the drive Also the read and write fu...

Page 94: ...R t SERVO 1 DEW j DEW SENSOR lDETECTION MAlNiJp J REEL FG J t REEL READ nl 1 ANP SENSOR SIGNAL OCESSOR Lr r S REEL S REEL 1 DRIVE MOTOR 1 1 r MODE 1 1 T REEL T REEL MOTOR ATF 1 DRIVE MOTOR CTRL lREEL DRIVEPCB l I 1 1 MODE MODE WRITE 1 DRIVE 1 MOTOR SIGNAL L______ J hr SSQR r 1 CAP Cn PCB 1 SERVO t SUBJJp 1 CYIDRV CYLINDER 4 1 CYLSERVO MOTOR I 1 r32KBXal T At I SRAM J CAPDRV CAPSTAN i PILOT I I MOT...

Page 95: ... I lI DRIVE INTERFACE LSI TO FROM DRIVE MICROPROCESSOR AND SIGNAL PROCESSING LSI Figure 8 2 OUTPUT ENABlE CHIP SELECT AOORESSBUS ACORESSICOfflROL UHES NCR 53C96 SCSI INTERFACE TO FROM SCSI BUS MEMORY r 256KB PROM MEMORY 512KB or 1MB DRAM AHA3101 I COMPRESSION I MEMORY 64KBSRAM Block Diagram SCSI Controller Python Models 4322NT and 4542NT DDS DC Drives 8 4 ...

Page 96: ... SERIAL wo INTERFACE PROCESSOR to Vfl 53C86 rA 10t SCSI DOl INTERFACE TTeR LSI LII BURST IIoeI8EC iIIII S 2Set B ne PROM DRAM Figure 8 3 Block Diagram SCSI Controller Python Models 4322NP 4542NP and 4352XP DDS DC Drives 8 5 1ODfW ...

Page 97: ...nal switches Additionally the internal models provide an accessible jumper at the rear of the drive that allows you to enable terminator power if needed The default for Python internal models is with terminator power disabled For external Python drives the default is with terminator power enabled NOTE Also a terminatorpower fuse is located at the rear ofinternal drives to provide protection from c...

Page 98: ...n is that a RAW check can be performed immediately after the data is written The cylinder rotates rapidly 2000 RPM in the same direction that the tape moves The wrap angle of the tape on the cylinder is approximately 90 degrees This wrap angle plus the slow tape speed minimize tape and head wear The combined movement of the tape and cylinder results in a relative head tape speed of 123 ips Figure ...

Page 99: ... 6 shows alternate tracks and alternate azimuth angles WRITE HEAD B 3 DATTRACKS HEAD AZIMUTH Figure 8 6 Alternate Azimuth Angles 8 3 2 Motors and Control Circuits The Python products use four direct drive brushless motors the capstan cylinder and two reel motors Using these small direct drive motors provides maximum reliability The cylinder motor rotates the cylinder The capstan motor moves the ta...

Page 100: ... A seamless append is the continuation of writing frames on the end of media BOM side of existing frames after a STOP such that the tracks are placed as if they were in a continuous sequence That is the servo system must be able to read the appended tracks without encountering discontinuity or gaps between tracks Performing a seamless append requires the highest precision and almost absolute accur...

Page 101: ...ed on detecting the open or closed state of four recognition holes in the DAT cassette The open closed state of these holes determine tape thickness cleaning cassette and whether the tape is prerecorded write protect or unrecorded These mechanical sensors plus the sensor for cassette in status are designed to comply with the ANSI DAT cassette specification The beginning of tape BOT and end of tape...

Page 102: ...the Python drive requires that the DDS head cleaning cassette be used every 25 hours ofread write operation and whenever the rectangular green cassette in place LED flashes during operation Chapter 9 discusses the DDS DAT head cleaning cassette in detail Both DAT data and head cleaning cassettes can be ordered from Archive and are packaged in multiples of five These small approximately 2 inches x ...

Page 103: ...E RECOGNITION HOLES 1 2 3 4 SLIDER LOCK 2 Figure 8 8 Cassette Design Features SLIDER LOCK 1 The cassette also provides for write protection so that existing data on the cassette is not overwritten A write protected cassette allows the existing data to be read but does not allow new data to be written to the tape NOTE A write protected cassette does not allow the error log in the System Area to be ...

Page 104: ...eaming Uncompressed Compressed backup Typical Maximum 90 180 2 00 4 00 8 00 60 120 1 32 2 64 5 28 45 90 99 1 98 3 96 30 60 66 1 32 2 64 23 45 49 98 1 96 NOTE With data compression tape capacity depends on the characteristics ofthe data being compressed Typical capacity reflects a 2 1 compression ration typical ofa mix of generalpurpose data files such as spreadsheet and wordprocessing files Maximu...

Page 105: ...ARCHIVE PYTHON DDS DC OAT DRIVES PRODUCT DESCRIPTION MANUAL NOTES 8 14 ...

Page 106: ...the presence ofaprerecorded audio tape Also see Section 3 7for a description ofLED operation To clean the heads of the Python drive use only an Archive qualified DDS DAT cleaning cassette designed for DDS drives Archive offers a cleaning cassette Model M7301 that you may order Cleaning cassettes are ordered and packaged in multiples of five The DDS cleaning cassette contains the correct recognitio...

Page 107: ...onditions Outside the Specified Operating Environment If the drive detects moisture dew the amber rectangular LED on the front panel flashes rapidly Following the guidelines listed below can minimize the possibiiity of extreme temperature or humidity conditions causing problems with the Python drive o Use DAT cassettes only at temperatures between SoC 40oF and 400C 1130F The cassettes can be store...

Page 108: ...s maintenance periods Operational time is assumed to be 30 of the power on time Operational time is the time the tape is loaded on the cylinder tape moving or cylinder rotating NOTE Archive does not warrant the statedMTBF as representative ofanyparticular unit installedfor customer use The failure rate quoted here is derived from a large database oftest samples Actual rates may vary from unit to u...

Page 109: ...ARCHIVE PYTHON DDS DC OAT DRIVES PRODUCT DESCRIPTION MANUAL NOTES 9 4 ...

Page 110: ...ber of errors divided by the total number of bits written or read Byte A group of 8 binary bits operated on as a unit Cassette An enclosure containing magnetic tape wound on two coplanar hubs and driven by an external drive Compression Ratio The ratio comparing the amount of uncompressed data to the amount of compressed data It is obtained by dividing the size of the uncompressed data by the size ...

Page 111: ...later be used to reconstruct errors during the data reading operation File A logical unit of information Fixed Disk A non removable hard disk All data must be transferred to and from the disk via the computer Frame Two adjacent tracks one A channel positive azimuth and one B channel negative azimuth Full high or full height Usually refers to a tape drive fitting in a vertical space of 3 1 2 inches...

Page 112: ...ape in order to provide a consistently unifonn RF envelope level Read Arter Write RAW Reading data immediately after it is written and writing the frame again if an error is found Reference System Area The second section of the tape on a DAT cassette which provides logs of usage and soft error occurrences Track A storage channel on recording tape For DAT specifically a diagonally positioned area o...

Page 113: ...ARCHIVE PYTHON DDS DC OAT DRIVES PRODUCT DESCRIPTION MANUAL NOTES A 4 ...

Page 114: ...tal Oxide Semiconductor Canadian Standard Association Digital Audio Tape Data Compression LempelZiv Digital Data Storage Digital Data Storage Data Compression Direct Memory Access Error Correction Code European Computer Manufacturers Association Electronically Eraseable Programmable Read Only Memory End of Data End of Media End Of Tape Federal Communications Commission Flux Transitions Per Inch Gr...

Page 115: ... Printed Circuit Board Plastic Quad Flat Pack Quad Flat Pack Quarter Inch Cartridge Drive Standards Incorporated Random Access Memory Read After Write Small Computer System Interface Transistor transistor logic Underwriters Laboratories Inc Volts Alternating Current Video Cassette Recorder Volts Direct Current Verband Deutscher Electrotechniker Video Tape Recorder 8 2 ...

Page 116: ...V W Amp Celsius or Centigrade centimeter decibels A weighted sound power reference one picowatt Fahrenheit foot or feet acceleration of a free falling body equal to 32 17 feet per second2 gigabyte Hertz inch kilo kilobyte kilogram kilohertz pound s meter mega megabits megabyte megaHertz millimeter millisecond revolutions per minute Volt Watt 8 3 ...

Page 117: ...ARCHIVE PYTHON DDS DC OAT DRIVES PRODUCT DESCRIPTION MANUAL NOTES 8 4 ...

Page 118: ...includes information about the REQUEST SENSE command and implementation notes regarding data compression Finally this appendix describes the WRITE DATA BUFFER command which can be used to download revised frrmware in the Python DDS DC drives that contain flash EEPROM Models 4322NP 4542NP and 4352XP C 2 MODE SELECT Page The layout of the MODE SELECT page for data compression control is shown in Tab...

Page 119: ... in the entity DDS DC format C 2 2 2 Report Error on Decompression RED Bit 05 The Report Error on Decompression RED bit 05 of the Decompression Control Byte 03 of the MODE SELECT page specifies when Check Conditions are reported to the host as follows o If the RED bit is 0 the Python drive generates a Check Condition for every compressed entity that it cannot decompress o If the RED bit is 1 the P...

Page 120: ...at changes o from uncompressed to compressed with an unsupported algorithm o from compressed with DClZ to compressed with an unsupported algorithm o from compressed with unsupported algorithm to uncompressed o from compressed with an unsupported algorithm to compressed with DCLl o from compressed with an unsupported algorithm to compressed with a different unsupported algorithm MEDIUM ERROR MEDIUM...

Page 121: ...disabled 01 Compression is enabled using the default algorithm DCLZ 02 1 F Illegal Request 20 Compression is enabled using the DClZ algorithm 21 FF Illegal Request C 3 MODE SENSE Page The layout of the MODE SENSE page for data compression control is shown in Table C 4 Table C 4 Data Compression MODE SENSE Page BYTE BITS 7 6 5 4 3 2 0 0 0 0 0 0 1 Page length OEh 2 DCE 1 0 0 0 0 0 0 3 DDE 0 RED 0 0 ...

Page 122: ...07 of the Decompression Control Byte 03 of the MODE SENSE page is set by the host The MODE SENSE command returns the value last set by the host o If the value is 1 the Python drive decompresses data that has been compressed on the tape before sending the data to the host during a READ command o If the value is 0 the Python drive does not decompress data sent to the host during a READ command and a...

Page 123: ... uncompressed Data last sent to the host was compressed using the DClZ algorithm Data last sent to the host was compressed using an algorithm other than the DClZ algorithm The contents of the DDS DC entity header algorithm byte is returned C 4 Request Sense Data During reading several exception conditions can occur that cause the Python DDS DC drive to send data to the host in the compressed DDS D...

Page 124: ...ondecompressing mode and compressed data is encountered A Python DDS DC drive may be in a nondecompressing mode for the following reasons o Decompression is disabled DOE D o The drive encounters an entity that was compressed with a non DOS DC algorithm Although the drive may be unable to decompress entities it may be reading a tape with compressed entities This implementation information deals wit...

Page 125: ...e set 1 and the Sense Key will be set to NO SENSE A strategy for reading compressed entities would be to set the RED bit to 1 and issue READ commands in variable length mode with a maximum transfer size and the SILl bit set A Check Condition would only be reported if the entity is larger than the transfer size or for the first entity encountered The maximum transfer size allowed by SCSI is FFFFFF ...

Page 126: ... host does not support decompression or if all was retrieved on the first READ Variable command the host can continue from LBA 65 C S 2 2 READ Fixed Command If a nondecompressing drive encounters an entity when a READ Fixed command is issued the drive returns either the number of bytes in one block or the total number of bytes in the entity whichever is smaller The drive then positions to the end ...

Page 127: ...ks to position past the entity C 6 WRITE DATA BUFFER 3Bh The WRITE DATA BUFFER Command is used in conjunction with the READ DATA BUFFER Command as a diagnostic function for testing the data buffer memory of the Python drive and confirming the SCSI bus integrity The medium is not accessed during the execution of this command The WRITE DATA BUFFER command can also be used to download the controller ...

Page 128: ...Available Length reported by the READ DATA BUFFER command If Mode 0 the initiator should ensure that the Transfer Length is not greater than 4 plus the Available Length that is returned in the header of the READ DATA BUFFER command If the Transfer Length is greater than the Available Length plus 4 the drive returns a Check Condition status with a Sense Key of Illegal Request If Mode 0 only the dat...

Page 129: ...programmed 30 seconds Then a power on reset occurs and commands are accepted If the firmware file is not valid a Check Condition is generated The Python drive is immediately ready to accept any appropriate command if Mode O Extended Sense Byte 02h SEt SE MESSAGE DESCRIPT ON KEY 04h Hardware Error OSh Illegal Request 06h Unit Attention C 12 Parity error on SCSI Bus or Python hard ware failure detec...

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Page 131: ...Archive Corporation 1650 Sunflower Avenue Costa l lesa CA 92626 714 641 1230 FAX 714 641 2590 ...

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