9914V TAPE UNIT

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1.4 StreamingTo maintain streaming, the next data block must be ready for synchronous transfer beforethe expiry of the Command Reinstruct Time (CRT) at the end of the current block.If the CRT is exceeded, a time penalty is incurred while a reposition sequence is executed;during this the tape is halted and spaced back sufficiently to allow ramping up tosynchronous speed before the next block. Figure 1.4 is a simplified reposition diagramwhich shows tape motion past the head, if the reinstruct time (at point B) is exceeded, if nonew command is received the tape halts at point F, if a new command is received itcontinues to the next block via point G.A normal length inter-blOCk gap (IBG) is written, whether streaming or after repositioning,except in special circumstances. In applications where the average host data rate isSlightly lower than required by continuous streaming, the user may effectively extend theusual CRT by the 'IBG size' option (configuration byte 12), to allow more time in which toassemble the data. This gives a write time throughput advantage.Where the average data rate is much lower than required by continuous streaming, theuser may be better advised to select the lower tape speed; this may appear to be aretrograde step but calculation will reveal whether low speed with no repositions givesfaster throughput than high speed with constant (longer) repositions.If the 'IBG size' configuration option is used but the extra time allowed between 'end ofdata' and a new command expires, the tape repositions to point F and awaits the nextcommand.The above paragraphs are a brief explanation of reposition during forward write conditions.In practice the cycle may be modified on-the-fly; eg if a reverse command is receivedduring the forward stop time, the reposition cycle is modified so that the new command isexecuted at the correct tape position.1.4.1 Command Reinstruct TimeThe command reinstruct time is defined as the time from 'end of data' to the latest point atwhich the next command may be accepted without a reposition cycle being executed.1.4.2 Access TimeAccess time is defined as the time taken to accelerate from stopped position to normalspeed and be ready to exchange data. The access time is shown in Figure 1.4, and isunaffected by the command reinstruct time.1.4.3 Positioning TimeThe positioning time is defined as the time taken to reach the stopped position (point F) inreadiness for the next command, when no new command is received before the end of thecommand reinstruct time.1.4.4 Repositioning TimeThe repositioning time is defined as the time taken to regain streaming speed (via points Bto G); this assumes that a new command is received between points Band F.1 - 8 <strong>9914V</strong> Servicing Manual 95 125456 (Draft Issue D)
~~ ____ 3_LO_C_K __________ IN_T_E_R_-_8L_O_C_K __ GA_P ______ 8_L_OC_K __ ~?,I COMMAND I i (FIRST--~)II RE-~7~~RUCT I~ I' DATA 8YTEA . B HGEDFIGURE 1.4 TYPICAL REPOSITION CYCLE1.4.5 Data RatesWhen a data is being transferred to tape, the data rate is determined by the tape speedand recording density (GCR, PE or NRZ). At 800, 1600, and 6250 bpi, the user may selectfrom two streaming speeds. The inter-relationship of tape speed, average data rate (anddata period) for the Pertee interface is detailed in Table 1.4.5. Note that the burst rate willbe higher.Density NRZ PE DPE GCR(bpi) 800 1600 3200 6250Speed 41.66125 41.66 125 62.5 62.5 41.66 125(ips)Data rate 33.3 100 66.6 200 200 200 260 781(kbytes/s)Data period 30 10 15 5 5 5 3.84 1.28(us)TABLE 1.4.5 <strong>9914V</strong> DATA RATESNote: the tape speeds normally referred to as '42 ips' and '62 ips' are actually 41.66 ipsand 62.5 ips.95 124766 (Draft Issue A) 9914 V overview 1 - 9
Page 1 and 2: 9914V TAPE UNITSERVICING MANUALDocu
Page 3 and 4: Bescheinigung des HerstellersHiermi
Page 5 and 6: INTERNAL CODE LICENSEPLEASE READ TH
Page 7 and 8: Table of ContentsSection 1 9914V Ov
Page 9 and 10: Section 3 Fault-Finding and Calibra
Page 11 and 12: 7.2 MaIns Transformer and Switch ..
Page 13 and 14: 7.17 Pertec Cache Interface Board .
Page 15 and 16: Illustrations of Parts8.2.1 TAPE PA
Page 17 and 18: 1.9914V OverviewThis 9914V Servicin
Page 19 and 20: 1.2.3 Access, Modularity, and Tools
Page 22 and 23: 1.3 Short-Form SpecificationTape Ty
Page 26 and 27: 1.5 lor. Mains SystemsD€finition:
Page 28 and 29: c) Miscellaneous circuits:i) to acc
Page 30 and 31: !IOperator"s PanelI~Mlcroprocessor~
Page 32 and 33: ) Drive CurrentsThe processor outpu
Page 34 and 35: ) LocatingIn order to check the loc
Page 36 and 37: 2.3 Data Control Board Description2
Page 39 and 40: Signal MODEa MODE1 MODE2 MODE3Meani
Page 41 and 42: 2.4.2.3 Write Power ControlThis blo
Page 43 and 44: Under fixed gain conditions, the am
Page 45 and 46: tilE THRESI-'OLD .. . t ...........
Page 47 and 48: 2.5.3.1 Control StrategyThere are f
Page 49 and 50: 2.6 Pre-Amplifier DescriptionThis s
Page 51 and 52: SKI I! SK2CJ '---..;;.......,;----'
Page 53 and 54: 2.8.3 SCSI InterfaceThe SCSI Contro
Page 55 and 56: 3.Fault Finding3.1 Scope of Section
Page 57 and 58: Hub Sensor pcb-PLHS,ITachoI~PlAL II
Page 59 and 60: DisplayExplanationSuspect FRU* BOT
Page 61 and 62: Display Explanation Suspect FRUOKTh
Page 63 and 64: 95 125456 (Draft Issue D) Fault Fin
Page 65 and 66: 3.3.4 On-line IndicationsThe full l
Page 67 and 68: 3.4 Fault-Finding Routines3.4.1 Int
Page 69 and 70: 0lFaultl Possible causesI nvestigat
Page 71 and 72: Faultl Possible causes Investigatio
Page 73 and 74: o11Fault I Possible causes Investig
Page 76 and 77:
I\.)I\.)Fault I Possible causesInve
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3.6 Manual Tape ThreadingSince the
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Re-calibration of the 98 i Li.\t ;;
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Configuration bytes 06 onwards are
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4.3 Configuration Byte 07 - Host In
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4.5 Configuration Byte 09 - Host In
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4.7 Configuration Byte 11 - Conditi
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4.9 - Configuration Byte 13 - Misce
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4.11 Configuration BytE.; '~g - Mis
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Option0102030405MeaningDNSDIS-1DNSD
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This page has no technical content4
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5.1.2 ',-ite CurrentFallaw the flow
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No. Function No. Function00 NULL PR
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Program 03NoteDescriptionILWD Line
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When run on-line, the programs expe
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Program 14DescriptionSet Block Leng
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Pro-:;r~UI 25Write, Backspace, Read
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Program 32 ~~;ce " ~IocksNotes - ;"
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i t 1 7 6 5 4 3 1 2 1 0I I I 1 I 1
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L should not be displayed with the
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EXIT Denotes the first exit point o
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Program 65Program 66DescriptionErro
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Prog"ram 69DescriptionError CodesIn
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Error Codes~: : AL f',l;:·)le cali
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Program 80Set Default NVR ValuesNot
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Program 98DescriptionError CodesCle
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6.4 Status Byte F4When an on-line d
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6.7 Status Byte F7Status byte F7 co
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· - -6.9 Status Byte F9Status byte
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6.11 Status By'"_-; ~ i ~Status byt
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6.16 Status Byte F16Bit Name Meanin
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it 7 bit 6bit 5 bit 4 bit 3 bit 2 b
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6.18 Condensed Status BytesThe 9914
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.....(J)ClWRITE ERR LOGbit 7 bit 62
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7.1.3 Electrical Servicing Equipmen
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7.2 Mains Tra.~- ad SWitchThe mains
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7.2.4.1 Wiring the AC Supply PlugWa
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7.4.4 SettingThe Servo Control perf
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Notes to Table 7.5.3:i) dual-functi
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ALLEN KEYE~ECTORSUTTONTOGGLEARf\iv)
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7.8 Tape Path Assembly7.8.1 Functio
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7.9.2 LocationThe tape cleaner is m
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7.11 rension Arm Assembly7.11.1 Fun
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The 9914V Data Central boards use E
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vi) Disconnect the IDC connectors t
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No attempt should be made to discon
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7.17.2 LocationThe PCI board is a p
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8.1 Available Spares8.1.1 Major Spa
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8.1.3 Subsidiary Spares Lisi:Parts
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\\-FIGURE 8.2.1TAPE PATH ASSEMBLY8-
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FIGURE 8.2.2 PARTS ABOVE THE TAPE P
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FIGURE 8.2.3(a) PARTS BELOW THE TAP
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FIGURE 8.2.3(b) PARTS BELOW THE TAP
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02 _____lG(3FIGURE 8.2.4 SUPPLY HUB
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\2II\0FIGURE 8.2.5 COOLING FAN ASSE
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00I~00
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--1LU---a--- 01FIGURE 8.2.7 ANALOGU
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FIGURE 8.2.8 DIGITAL DATA PATHS BOA
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FIGURE 8.2.9 DATA CONTROL BOARD8 -
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00If\.)0>
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l-ClI I",-...1\I,II1\O~\III\----FIG
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loll 'eOIl~~10-I
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FIGURE 8.2.13 OPERATOR PANEL AND SW
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o17--ljII 1011----~.....FIGURE 8.2.
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FIGURE 8.2.15 MAINS SWITCH8 - 36 99
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-----.\2~\\ ~1~IOFIGURE 8.3.1SCSI B
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16 ________15 Y! ! II I' I1 I' ,0\
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\0{1b'5 13 16FIGURE 8.3.3 DC POWER
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~-------~IFIGURE 8.4.1MAINS TRANSFO
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FIGURE 8.4.2 HUB SENSOR PCB8 - 46 9
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12II10-lWI--fl---OIFIGURE 8.4.3 AIR
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D14DFIGURE 8.4.4 AC FUSE KIT8 - 50
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o\ft~o·~)bJa:1FIGURE 8.4.5 DC FUSE
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8 - 54MOTHERBOARDFIGURE 8.4.6 95 12
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This page has no 'technical content
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