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Writer parameters training

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Kheng Kait Lim

The document discusses optimization of writer parameters for a Western Digital hard drive. It describes using Taguchi optimization and 1-dimensional sweeping of various writer parameters, including write current, overshoot amplitude, and overshoot duration. The goals are to provide optimized settings that reduce error metrics like error rate modulation and acoustic noise. Examples of Taguchi tables are provided that show averaged vibration margin metric values used to select optimal parameter values.

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© 2013 WESTERN DIGITAL TECHNOLOGIES, INC. ALL RIGHTS RESERVED Writer Parameters Training KhengKait Channel Hardware WD CONFIDENTIAL
Writer waveform Writer Optimization Writer optimization results vs big ARCO results 1 2 3 4 5 Zone EM TD 6 7 8 Backgrounds of writer path parameters Agenda How to manipulate writer parameters Conclusion
3 Backgrounds of write path parameters  Objectives: provide optimized settings and results  Failures type: EM combo, AC, 0 OTRC, DLG.  Employed in PTMs: Mini ARCO, TaKO, Full ARCO, Hot ARCO, BigTaKO, Big ARCO  Optimization functions: Taguchi, 1-D OSA/OSD/IW sweeping  Influence on drive parameters: EM, OTRC, ATI, PMET OW/SNR
4 Topics to cover in this training Write path Basic Writer waveform Algo. Taguchi 1-D writer Opti. Tub/XMMS review Advance RFPE & ATI Write precom Eqn. based IW ISI, Seed & ITIC
Writer Waveform KhengKait Channel Hardware Writer waveform: IW, OSA, OSD WD CONFIDENTIAL
6 Writer Waveform: IW, OSA, OSD  Matching settings of different preamp.  Link: http://exapps04.wdc.com/wdwwa/
7 Writer Waveform: IW, OSA, OSD  Matching settings of different preamp.  Link: http://exapps04.wdc.com/wdwwa/ IW Rise Time OSA OSA
8 Write Current (IW)  Fix OSD 5 DAC, OSA 5 DAC, IW 40,45,50,60 IW 40 IW 45 IW 50 IW 60
9 Overshoot Amplitude (OSA)  Fix IW 55 DAC, 5 OSD DAC and sweep OSA:1,5,10,15 OSA 1 OSA 5 OSA 10 OSA 15
10 Overshoot Duration (OSD)  Fix IW 55 DAC, OSA 5 DAC and OSD:1,5,10,15 OSD 1 OSD 5 OSD 10 OSD 15
11 Writer Waveform Analyzer  Settings matching for different preamps  Link: http://exapps04.wdc.com/wdwwa/
Writer Optimization KhengKait Channel Hardware Taguchi, 1-Dimension sweeping WD CONFIDENTIAL
13 Optimization sequence NLDOFF FIR & MRA Boost & CutOff VMJOG curvefit SAT_OWTaguchi OSA curvefit OSD curvefit IW curvefit
14 Know the TUBs: Head1 Zone 2 Writer TUBs (1) Tub : TAGU_S Default Dac : 2DH Selected Dac : 38H DAC COUNT VALUE 1123H 0014H 01FEFFH *********************************************************** 2223H 001CH 01D113H **************************************************** 4423H 0030H 00E2BCH ****************** 5523H 003CH 0070FAH ** 6623H 004AH 0063B1H * 122AH 002CH 014D1BH ********************************* 242AH 0039H 007CD5H **** 452AH 004CH 006373H * 562AH 0059H 00698BH * 612AH 0042H 0069A0H * 1431H 0049H 006BAAH ** 2531H 0054H 006AC8H ** 4631H 0069H 006D57H ** 5131H 0053H 0067CCH * 6231H 0060H 00669BH * 1538H 0065H 00680AH * 2638H 0072H 0068A2H * 4138H 0066H 0066F0H * 5238H 0073H 00654EH * 6438H 0088H 006F1FH ** 163FH 0083H 006C0AH ** 213FH 0073H 006588H * 423FH 0086H 0069F7H * 543FH 009BH 0070F5H ** 653FH 00ABH 00744BH *** 0001H 0001H 00E8C4H ******************* 0002H 0002H 00B492H ************ 0004H 0003H 0080E2H ***** 0005H 0004H 006B50H ** 0006H 0005H 006B11H ** 0001H 0001H 00B8FAH ************* 0002H 0002H 00DD9CH ****************** 0004H 0003H 0088A9H ****** 0005H 0004H 006BE8H ** 0006H 0005H 006973H * 0023H 0001H 011B18H ************************** 002AH 0002H 0099B6H ******** 0031H 0003H 006A09H * 0038H 0004H 0068CEH * 003FH 0005H 006CF5H ** 0006H 0005H 006B11H ** 0006H 0005H 006973H * 0038H 0004H 0068CEH * (2) Tub : OSAMPS Default Dac : 6H Selected Dac : 1H DAC COUNT VALUE 0001H 0066H 007FAFH * 0002H 006EH 0080C8H *** 0003H 0076H 0089FFH **************************** 0004H 007FH 008CE2H ************************************ 0005H 0088H 008F6EH ****************************************** 0006H 0092H 00955BH ********************************************************** (3) Tub : OSDURS Default Dac : 6H Selected Dac : 4H DAC COUNT VALUE 0001H 0051H 00851DH ********************************************************** 0002H 0055H 00854DH *********************************************************** 0003H 005AH 007D84H * 0004H 005EH 007E3DH ****** 0005H 0062H 007F6CH *************** 0006H 0066H 007EEDH *********** (4) Tub : IW_SCE Default Dac : 37H Selected Dac : 39H DAC COUNT VALUE 0023H 001EH 01C44CH ********************************************************** 0025H 0024H 01A407H ***************************************************** 0027H 002AH 01741BH ********************************************* 0029H 0030H 013324H *********************************** 002BH 0036H 00F52FH ************************* 002DH 003CH 00A611H ************ 002FH 0043H 008DE6H ******** 0031H 0049H 00772DH **** 0033H 0050H 00703FH *** 0035H 0057H 0065ABH * 0037H 005EH 0066F9H * 0039H 0065H 006328H * 003BH 006CH 0065E4H * 003DH 0073H 0061D3H * 003FH 007BH 006259H *
15 How L25 Taguchi defined = range / 5 WD Confidential
16 Taguchi TUB: DAC column & VMM (1) Tub : TAGU_S Default Dac : 2DH Selected Dac : 38H DAC COUNT VALUE 1123H 0014H 01FEFFH *********************************************************** 2223H 001CH 01D113H **************************************************** 4423H 0030H 00E2BCH ****************** 5523H 003CH 0070FAH ** 6623H 004AH 0063B1H * 122AH 002CH 014D1BH ********************************* 242AH 0039H 007CD5H **** 452AH 004CH 006373H * 562AH 0059H 00698BH * 612AH 0042H 0069A0H * 1431H 0049H 006BAAH ** 2531H 0054H 006AC8H ** 4631H 0069H 006D57H ** 5131H 0053H 0067CCH * 6231H 0060H 00669BH * 1538H 0065H 00680AH * 2638H 0072H 0068A2H * 4138H 0066H 0066F0H * 5238H 0073H 00654EH * 6438H 0088H 006F1FH ** 163FH 0083H 006C0AH ** 213FH 0073H 006588H * 423FH 0086H 0069F7H * 543FH 009BH 0070F5H ** 653FH 00ABH 00744BH *** 0001H 0001H 00E8C4H ******************* 0002H 0002H 00B492H ************ 0004H 0003H 0080E2H ***** 0005H 0004H 006B50H ** 0006H 0005H 006B11H ** 0001H 0001H 00B8FAH ************* 0002H 0002H 00DD9CH ****************** 0004H 0003H 0088A9H ****** 0005H 0004H 006BE8H ** 0006H 0005H 006973H * 0023H 0001H 011B18H ************************** 002AH 0002H 0099B6H ******** 0031H 0003H 006A09H * 0038H 0004H 0068CEH * 003FH 0005H 006CF5H ** 0006H 0005H 006B11H ** 0006H 0005H 006973H * 0038H 0004H 0068CEH * 1123H 0014H 01FEFFH *********************************************************** 1:OSA 1:OSD 23:IW L25 taguchi sweep to reduce sweeping samples. Too time consuming If performing full permutation sweep. Average by OSA Average by OSD Average by IW Taguchi selection Viterbi Margin Metrix (VMM). Treat VMM as error rate, lower value means better signal.
17 Taguchi tub (1) Tub : TAGU_S Default Dac : 2DH Selected Dac : 38H DAC COUNT VALUE 1123H 0014H 01FEFFH *********************************************************** 2223H 001CH 01D113H **************************************************** 4423H 0030H 00E2BCH ****************** 5523H 003CH 0070FAH ** 6623H 004AH 0063B1H * 122AH 002CH 014D1BH ********************************* 242AH 0039H 007CD5H **** 452AH 004CH 006373H * 562AH 0059H 00698BH * 612AH 0042H 0069A0H * 1431H 0049H 006BAAH ** 2531H 0054H 006AC8H ** 4631H 0069H 006D57H ** 5131H 0053H 0067CCH * 6231H 0060H 00669BH * 1538H 0065H 00680AH * 2638H 0072H 0068A2H * 4138H 0066H 0066F0H * 5238H 0073H 00654EH * 6438H 0088H 006F1FH ** 163FH 0083H 006C0AH ** 213FH 0073H 006588H * 423FH 0086H 0069F7H * 543FH 009BH 0070F5H ** 653FH 00ABH 00744BH *** 0001H 0001H 00E8C4H ******************* 0002H 0002H 00B492H ************ 0004H 0003H 0080E2H ***** 0005H 0004H 006B50H ** 0006H 0005H 006B11H ** 0001H 0001H 00B8FAH ************* 0002H 0002H 00DD9CH ****************** 0004H 0003H 0088A9H ****** 0005H 0004H 006BE8H ** 0006H 0005H 006973H * 0023H 0001H 011B18H ************************** 002AH 0002H 0099B6H ******** 0031H 0003H 006A09H * 0038H 0004H 0068CEH * 003FH 0005H 006CF5H ** 0006H 0005H 006B11H ** 0006H 0005H 006973H * 0038H 0004H 0068CEH * Average by each OSA setting Taguchi selection: IW : 0x38; OSA 0x6; OSD 0x6 Avg by OSA VMM(decimal) VMM (hex) 1 59588.8 E8C4 2 51284.5 C854 4 34461.5 869D 5 27111.75 69E7 6 26818.75 68C2 Min value is selected
18 Head1 Zone 2: Taguchi and 1-D sweeping (1) Tub : TAGU_S Default Dac : 2DH Selected Dac : 38H DAC COUNT VALUE 1123H 0014H 01FEFFH *********************************************************** 2223H 001CH 01D113H **************************************************** 4423H 0030H 00E2BCH ****************** 5523H 003CH 0070FAH ** 6623H 004AH 0063B1H * 122AH 002CH 014D1BH ********************************* 242AH 0039H 007CD5H **** 452AH 004CH 006373H * 562AH 0059H 00698BH * 612AH 0042H 0069A0H * 1431H 0049H 006BAAH ** 2531H 0054H 006AC8H ** 4631H 0069H 006D57H ** 5131H 0053H 0067CCH * 6231H 0060H 00669BH * 1538H 0065H 00680AH * 2638H 0072H 0068A2H * 4138H 0066H 0066F0H * 5238H 0073H 00654EH * 6438H 0088H 006F1FH ** 163FH 0083H 006C0AH ** 213FH 0073H 006588H * 423FH 0086H 0069F7H * 543FH 009BH 0070F5H ** 653FH 00ABH 00744BH *** 0001H 0001H 00E8C4H ******************* 0002H 0002H 00B492H ************ 0004H 0003H 0080E2H ***** 0005H 0004H 006B50H ** 0006H 0005H 006B11H ** 0001H 0001H 00B8FAH ************* 0002H 0002H 00DD9CH ****************** 0004H 0003H 0088A9H ****** 0005H 0004H 006BE8H ** 0006H 0005H 006973H * 0023H 0001H 011B18H ************************** 002AH 0002H 0099B6H ******** 0031H 0003H 006A09H * 0038H 0004H 0068CEH * 003FH 0005H 006CF5H ** 0006H 0005H 006B11H ** 0006H 0005H 006973H * 0038H 0004H 0068CEH * (2) Tub : OSAMPS Default Dac : 6H Selected Dac : 1H DAC COUNT VALUE 0001H 0066H 007FAFH * 0002H 006EH 0080C8H *** 0003H 0076H 0089FFH **************************** 0004H 007FH 008CE2H ************************************ 0005H 0088H 008F6EH ****************************************** 0006H 0092H 00955BH ********************************************************** Default OSD (from Taguchi): 6H Default IW (from Taguchi): 38H OSA = 1H OSD = 6H IW = 38H
19 Head1 Zone 2 Writer TUBs (1) Tub : TAGU_S Default Dac : 2DH Selected Dac : 38H DAC COUNT VALUE 1123H 0014H 01FEFFH *********************************************************** 2223H 001CH 01D113H **************************************************** 4423H 0030H 00E2BCH ****************** 5523H 003CH 0070FAH ** 6623H 004AH 0063B1H * 122AH 002CH 014D1BH ********************************* 242AH 0039H 007CD5H **** 452AH 004CH 006373H * 562AH 0059H 00698BH * 612AH 0042H 0069A0H * 1431H 0049H 006BAAH ** 2531H 0054H 006AC8H ** 4631H 0069H 006D57H ** 5131H 0053H 0067CCH * 6231H 0060H 00669BH * 1538H 0065H 00680AH * 2638H 0072H 0068A2H * 4138H 0066H 0066F0H * 5238H 0073H 00654EH * 6438H 0088H 006F1FH ** 163FH 0083H 006C0AH ** 213FH 0073H 006588H * 423FH 0086H 0069F7H * 543FH 009BH 0070F5H ** 653FH 00ABH 00744BH *** 0001H 0001H 00E8C4H ******************* 0002H 0002H 00B492H ************ 0004H 0003H 0080E2H ***** 0005H 0004H 006B50H ** 0006H 0005H 006B11H ** 0001H 0001H 00B8FAH ************* 0002H 0002H 00DD9CH ****************** 0004H 0003H 0088A9H ****** 0005H 0004H 006BE8H ** 0006H 0005H 006973H * 0023H 0001H 011B18H ************************** 002AH 0002H 0099B6H ******** 0031H 0003H 006A09H * 0038H 0004H 0068CEH * 003FH 0005H 006CF5H ** 0006H 0005H 006B11H ** 0006H 0005H 006973H * 0038H 0004H 0068CEH * (2) Tub : OSAMPS Default Dac : 6H Selected Dac : 1H DAC COUNT VALUE 0001H 0066H 007FAFH * 0002H 006EH 0080C8H *** 0003H 0076H 0089FFH **************************** 0004H 007FH 008CE2H ************************************ 0005H 0088H 008F6EH ****************************************** 0006H 0092H 00955BH ********************************************************** (3) Tub : OSDURS Default Dac : 6H Selected Dac : 4H DAC COUNT VALUE 0001H 0051H 00851DH ********************************************************** 0002H 0055H 00854DH *********************************************************** 0003H 005AH 007D84H * 0004H 005EH 007E3DH ****** 0005H 0062H 007F6CH *************** 0006H 0066H 007EEDH *********** Default OSA (from 1-D OSA): 1H Default IW (from Taguchi): 38H
20 Head1 Zone 2 Writer TUBs (1) Tub : TAGU_S Default Dac : 2DH Selected Dac : 38H DAC COUNT VALUE 1123H 0014H 01FEFFH *********************************************************** 2223H 001CH 01D113H **************************************************** 4423H 0030H 00E2BCH ****************** 5523H 003CH 0070FAH ** 6623H 004AH 0063B1H * 122AH 002CH 014D1BH ********************************* 242AH 0039H 007CD5H **** 452AH 004CH 006373H * 562AH 0059H 00698BH * 612AH 0042H 0069A0H * 1431H 0049H 006BAAH ** 2531H 0054H 006AC8H ** 4631H 0069H 006D57H ** 5131H 0053H 0067CCH * 6231H 0060H 00669BH * 1538H 0065H 00680AH * 2638H 0072H 0068A2H * 4138H 0066H 0066F0H * 5238H 0073H 00654EH * 6438H 0088H 006F1FH ** 163FH 0083H 006C0AH ** 213FH 0073H 006588H * 423FH 0086H 0069F7H * 543FH 009BH 0070F5H ** 653FH 00ABH 00744BH *** 0001H 0001H 00E8C4H ******************* 0002H 0002H 00B492H ************ 0004H 0003H 0080E2H ***** 0005H 0004H 006B50H ** 0006H 0005H 006B11H ** 0001H 0001H 00B8FAH ************* 0002H 0002H 00DD9CH ****************** 0004H 0003H 0088A9H ****** 0005H 0004H 006BE8H ** 0006H 0005H 006973H * 0023H 0001H 011B18H ************************** 002AH 0002H 0099B6H ******** 0031H 0003H 006A09H * 0038H 0004H 0068CEH * 003FH 0005H 006CF5H ** 0006H 0005H 006B11H ** 0006H 0005H 006973H * 0038H 0004H 0068CEH * (2) Tub : OSAMPS Default Dac : 6H Selected Dac : 1H DAC COUNT VALUE 0001H 0066H 007FAFH * 0002H 006EH 0080C8H *** 0003H 0076H 0089FFH **************************** 0004H 007FH 008CE2H ************************************ 0005H 0088H 008F6EH ****************************************** 0006H 0092H 00955BH ********************************************************** (3) Tub : OSDURS Default Dac : 6H Selected Dac : 4H DAC COUNT VALUE 0001H 0051H 00851DH ********************************************************** 0002H 0055H 00854DH *********************************************************** 0003H 005AH 007D84H * 0004H 005EH 007E3DH ****** 0005H 0062H 007F6CH *************** 0006H 0066H 007EEDH *********** (4) Tub : IW_SCE Default Dac : 37H Selected Dac : 39H DAC COUNT VALUE 0023H 001EH 01C44CH ********************************************************** 0025H 0024H 01A407H ***************************************************** 0027H 002AH 01741BH ********************************************* 0029H 0030H 013324H *********************************** 002BH 0036H 00F52FH ************************* 002DH 003CH 00A611H ************ 002FH 0043H 008DE6H ******** 0031H 0049H 00772DH **** 0033H 0050H 00703FH *** 0035H 0057H 0065ABH * 0037H 005EH 0066F9H * 0039H 0065H 006328H * 003BH 006CH 0065E4H * 003DH 0073H 0061D3H * 003FH 007BH 006259H * Default OSA (from 1-D OSA): 1H Default OSD (from 1-D OSD): 4H  IW selected = median of 5 min value.
21 Trend of good settings (1) Tub : TAGU_S Default Dac : 2DH Selected Dac : 38H DAC COUNT VALUE 1123H 0014H 01FEFFH *********************************************************** 2223H 001CH 01D113H **************************************************** 4423H 0030H 00E2BCH ****************** 5523H 003CH 0070FAH ** 6623H 004AH 0063B1H * 122AH 002CH 014D1BH ********************************* 242AH 0039H 007CD5H **** 452AH 004CH 006373H * 562AH 0059H 00698BH * 612AH 0042H 0069A0H * 1431H 0049H 006BAAH ** 2531H 0054H 006AC8H ** 4631H 0069H 006D57H ** 5131H 0053H 0067CCH * 6231H 0060H 00669BH * 1538H 0065H 00680AH * 2638H 0072H 0068A2H * 4138H 0066H 0066F0H * 5238H 0073H 00654EH * 6438H 0088H 006F1FH ** 163FH 0083H 006C0AH ** 213FH 0073H 006588H * 423FH 0086H 0069F7H * 543FH 009BH 0070F5H ** 653FH 00ABH 00744BH *** 0001H 0001H 00E8C4H ******************* 0002H 0002H 00B492H ************ 0004H 0003H 0080E2H ***** 0005H 0004H 006B50H ** 0006H 0005H 006B11H ** 0001H 0001H 00B8FAH ************* 0002H 0002H 00DD9CH ****************** 0004H 0003H 0088A9H ****** 0005H 0004H 006BE8H ** 0006H 0005H 006973H * 0023H 0001H 011B18H ************************** 002AH 0002H 0099B6H ******** 0031H 0003H 006A09H * 0038H 0004H 0068CEH * 003FH 0005H 006CF5H ** 0006H 0005H 006B11H ** 0006H 0005H 006973H * 0038H 0004H 0068CEH *  Taguchi selects: 0x6 OSA; 0x6 OSD; 0x38(56) IW  1-D sweep select OSA 0x1; OSD 0x4; IW 57
22 Messages from Taguchi tub  Taguchi select IW 0x38, OSA 0x6, OSD 0x6  Taguchi sweep prefers higher OSA/OSD for optimum IW  1-D sweep select OSA 0x1; OSD 0x4; IW 57
23 Saturation trend in Taguchi tub  Taguchi select IW 0x38, OSA 0x6, OSD 0x6  Taguchi sweep prefers higher OSA/OSD for optimum IW  1-D sweep select OSA 0x1; OSD 0x4; IW 57
Writer optimization results vs big ARCO results KhengKait Channel Hardware Result comparison WD CONFIDENTIAL
Taguchi tub  Taguchi selects IW 0x38, OSA 0x6, OSD 0x6  Taguchi sweep prefers higher OSA/OSD for optimum IW  1-D sweep selects IW 0x39; OSA 0x1, OSD 0x4  Taguchi trend is matching with Big ARCO
Taguchi tub  Taguchi select IW 0x38, OSA 0x6, OSD 0x6  Taguchi sweep prefers higher OSA/OSD for optimum IW  1-D sweep select OSA 0x1; OSD 0x4; IW 57 IW 56; OSD 6; sweep OSA
27 Taguchi tub  Taguchi sweep prefers higher OSA/OSD for optimum IW  1-D sweep select OSA 0x1; OSD 0x4; IW 57 4 IW 56; OSA 1; sweep OSD
28 Taguchi tub  Taguchi sweep prefers higher OSA/OSD for optimum IW  1-D sweep select OSA 0x1; OSD 0x4; IW 57 4 OSD4; OSA 1; sweep IW
Reason why BigARCO recommend settings is Fail KhengKait Channel Hardware Explain via illustration & XMMS data analysis WD CONFIDENTIAL
30 Big ARCO recommend settings  still possible for 1-D sweep to choose lower (bad) OSA/OSD settings
31 List out GIDs used in TaKO and FullARCO Zone information (OD, MD, ID, Rsv)  OD 1, MD 10, ID 20, reserve  Table: 8 = cold, 9 = amb, 10= hot WD Confidential
32 XMMS: IW, OSA & OSD in TaKO  New setting: saturated  Old setting: bias to higher IW OSA OSD IW  New setting: possible to choose lower (bad) OSA/OSD combination
33 TaKO results  Old settings has more poor tilt end than new settings
34 TaKO results  Old settings has more poor tilt end than new settings
35 TaKO result analysis  Old settings has more poor tilt end than new settings  Inspect from average perspective, new and old settings are comparable (since higher IW/OSA/OSD) are able to obtain saturated result.  only applicable to ambient but hot temperature.  1-D sweeping causing big ARCO recommend settings not suitable to use writer optimization unless the following is changed:  (Code change)Optimization sequence changed to IW  OSD  OSA  Replace 1-D optimization with 2-level Taguchi or other equivalent design.
TaKO results  EM at OD: comparable. OSA/OSD of new settings at OD are higher than MD and ID.
 TPI/KFCI are more dominant effect in EM DC shift.  Writer parameters is just for saturated result but KFCI able to gives a big leap.
 from another writer parameters evals(60L vs 60K), I takes same TPI/KFCI binning (less TPI/KFCI changes) of same drive, lower OSA/OSD tend to have poorer EM result.  Conclusion: with Codata with BigARCO recommend settings, it is still possible to select poor OSA/OSD settings which end up IW selects higher end settings.
New Codata with saturated choice KhengKait Channel Hardware To illustrate the failure WD CONFIDENTIAL
40 Big ARCO recommend settings  Selections will always fall into saturation(good) region --> all settings are good (if not ATI)  bell-curve XMMS distribution.  Need to watch out ATI
41 Same drive XMMS review  JN.B.YA (baseline: old settings) vs JN.B.YN(new settings)  Quantity of drive: 46  Hypothesis/expectation: comparable result with lower count on poor tilt-end  PMR: effect of writer parameters on EM/SNR is reduced compared to LMR. Sufficient writer energy will do in order to obtain saturated SNR.  according to Marvel engineer.  Review result:  TPI/KFCI: identical/comparable  EM: comparable with lower poor tilt-end distribution
42 Same drive XMMS review: TaKO  TPI/KFCI: identical/comparable  EM: comparable with new settings slightly better
 Comments only applied for new settings  OSA: bias to lower mid range (5~10)  not an signature of saturation  OSD: bias to median 10 ( sweep range 5~15, median 10=)  normal distribution = signature of saturation.  IW: normal distribution = signature of saturation.  Conclusion: results look good in overall, need to monitor OSA  IMHO, less chance cos it is covered by OSD and IW.  It is always a plus if there is a way to lowering down IW (green tech).
 There is one outlier at new settings consistently.  Need to know the SN for checking.
45 Same drive XMMS review: post TaKO  EM: comparable
46 Same drive XMMS review: post TaKO  Same comment as in TaKO
FA: 0 OTRC Failure KhengKait Channel Hardware To illustrate the failure WD CONFIDENTIAL
48 Failure Analysis - samples  Backgrounds: new head M11P is introduced in F2 & F3 build. Most failures are writer parameters related.  Failures type: EM combo, AC, 0 OTRC, DLG.  Symptom: OSA/OSD selection are in contrast with Taguchi selection  Taguchi: clean tub and preferring higher OSA/OSD. low OSA/OSD yields poor result.  1-Dimension OSA/OSD: saturated and values selected << Taguchi selection  1-dimension IW: clean bath tub.  Ambient performance is ok with low OSA/OSD but degrade in hot (SNR degraded)  Bench FA: increasing OSA/OSD able to pass the failure  Big ARCO result: prefers higher OSA/OSD
49 0 OTRC failure Run at hot  Amb performance is good.  Hot performance is poor
50 Writer parameters
51 Conclusion  XMMS results look good. New settings are OK to go.  Things to watch-out: BI results and OSA optimization.

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Writer parameters training

  • 1. © 2013 WESTERN DIGITAL TECHNOLOGIES, INC. ALL RIGHTS RESERVED Writer Parameters Training KhengKait Channel Hardware WD CONFIDENTIAL
  • 2. Writer waveform Writer Optimization Writer optimization results vs big ARCO results 1 2 3 4 5 Zone EM TD 6 7 8 Backgrounds of writer path parameters Agenda How to manipulate writer parameters Conclusion
  • 3. 3 Backgrounds of write path parameters  Objectives: provide optimized settings and results  Failures type: EM combo, AC, 0 OTRC, DLG.  Employed in PTMs: Mini ARCO, TaKO, Full ARCO, Hot ARCO, BigTaKO, Big ARCO  Optimization functions: Taguchi, 1-D OSA/OSD/IW sweeping  Influence on drive parameters: EM, OTRC, ATI, PMET OW/SNR
  • 4. 4 Topics to cover in this training Write path Basic Writer waveform Algo. Taguchi 1-D writer Opti. Tub/XMMS review Advance RFPE & ATI Write precom Eqn. based IW ISI, Seed & ITIC
  • 5. Writer Waveform KhengKait Channel Hardware Writer waveform: IW, OSA, OSD WD CONFIDENTIAL
  • 6. 6 Writer Waveform: IW, OSA, OSD  Matching settings of different preamp.  Link: http://exapps04.wdc.com/wdwwa/
  • 7. 7 Writer Waveform: IW, OSA, OSD  Matching settings of different preamp.  Link: http://exapps04.wdc.com/wdwwa/ IW Rise Time OSA OSA
  • 8. 8 Write Current (IW)  Fix OSD 5 DAC, OSA 5 DAC, IW 40,45,50,60 IW 40 IW 45 IW 50 IW 60
  • 9. 9 Overshoot Amplitude (OSA)  Fix IW 55 DAC, 5 OSD DAC and sweep OSA:1,5,10,15 OSA 1 OSA 5 OSA 10 OSA 15
  • 10. 10 Overshoot Duration (OSD)  Fix IW 55 DAC, OSA 5 DAC and OSD:1,5,10,15 OSD 1 OSD 5 OSD 10 OSD 15
  • 11. 11 Writer Waveform Analyzer  Settings matching for different preamps  Link: http://exapps04.wdc.com/wdwwa/
  • 12. Writer Optimization KhengKait Channel Hardware Taguchi, 1-Dimension sweeping WD CONFIDENTIAL
  • 13. 13 Optimization sequence NLDOFF FIR & MRA Boost & CutOff VMJOG curvefit SAT_OWTaguchi OSA curvefit OSD curvefit IW curvefit
  • 14. 14 Know the TUBs: Head1 Zone 2 Writer TUBs (1) Tub : TAGU_S Default Dac : 2DH Selected Dac : 38H DAC COUNT VALUE 1123H 0014H 01FEFFH *********************************************************** 2223H 001CH 01D113H **************************************************** 4423H 0030H 00E2BCH ****************** 5523H 003CH 0070FAH ** 6623H 004AH 0063B1H * 122AH 002CH 014D1BH ********************************* 242AH 0039H 007CD5H **** 452AH 004CH 006373H * 562AH 0059H 00698BH * 612AH 0042H 0069A0H * 1431H 0049H 006BAAH ** 2531H 0054H 006AC8H ** 4631H 0069H 006D57H ** 5131H 0053H 0067CCH * 6231H 0060H 00669BH * 1538H 0065H 00680AH * 2638H 0072H 0068A2H * 4138H 0066H 0066F0H * 5238H 0073H 00654EH * 6438H 0088H 006F1FH ** 163FH 0083H 006C0AH ** 213FH 0073H 006588H * 423FH 0086H 0069F7H * 543FH 009BH 0070F5H ** 653FH 00ABH 00744BH *** 0001H 0001H 00E8C4H ******************* 0002H 0002H 00B492H ************ 0004H 0003H 0080E2H ***** 0005H 0004H 006B50H ** 0006H 0005H 006B11H ** 0001H 0001H 00B8FAH ************* 0002H 0002H 00DD9CH ****************** 0004H 0003H 0088A9H ****** 0005H 0004H 006BE8H ** 0006H 0005H 006973H * 0023H 0001H 011B18H ************************** 002AH 0002H 0099B6H ******** 0031H 0003H 006A09H * 0038H 0004H 0068CEH * 003FH 0005H 006CF5H ** 0006H 0005H 006B11H ** 0006H 0005H 006973H * 0038H 0004H 0068CEH * (2) Tub : OSAMPS Default Dac : 6H Selected Dac : 1H DAC COUNT VALUE 0001H 0066H 007FAFH * 0002H 006EH 0080C8H *** 0003H 0076H 0089FFH **************************** 0004H 007FH 008CE2H ************************************ 0005H 0088H 008F6EH ****************************************** 0006H 0092H 00955BH ********************************************************** (3) Tub : OSDURS Default Dac : 6H Selected Dac : 4H DAC COUNT VALUE 0001H 0051H 00851DH ********************************************************** 0002H 0055H 00854DH *********************************************************** 0003H 005AH 007D84H * 0004H 005EH 007E3DH ****** 0005H 0062H 007F6CH *************** 0006H 0066H 007EEDH *********** (4) Tub : IW_SCE Default Dac : 37H Selected Dac : 39H DAC COUNT VALUE 0023H 001EH 01C44CH ********************************************************** 0025H 0024H 01A407H ***************************************************** 0027H 002AH 01741BH ********************************************* 0029H 0030H 013324H *********************************** 002BH 0036H 00F52FH ************************* 002DH 003CH 00A611H ************ 002FH 0043H 008DE6H ******** 0031H 0049H 00772DH **** 0033H 0050H 00703FH *** 0035H 0057H 0065ABH * 0037H 005EH 0066F9H * 0039H 0065H 006328H * 003BH 006CH 0065E4H * 003DH 0073H 0061D3H * 003FH 007BH 006259H *
  • 15. 15 How L25 Taguchi defined = range / 5 WD Confidential
  • 16. 16 Taguchi TUB: DAC column & VMM (1) Tub : TAGU_S Default Dac : 2DH Selected Dac : 38H DAC COUNT VALUE 1123H 0014H 01FEFFH *********************************************************** 2223H 001CH 01D113H **************************************************** 4423H 0030H 00E2BCH ****************** 5523H 003CH 0070FAH ** 6623H 004AH 0063B1H * 122AH 002CH 014D1BH ********************************* 242AH 0039H 007CD5H **** 452AH 004CH 006373H * 562AH 0059H 00698BH * 612AH 0042H 0069A0H * 1431H 0049H 006BAAH ** 2531H 0054H 006AC8H ** 4631H 0069H 006D57H ** 5131H 0053H 0067CCH * 6231H 0060H 00669BH * 1538H 0065H 00680AH * 2638H 0072H 0068A2H * 4138H 0066H 0066F0H * 5238H 0073H 00654EH * 6438H 0088H 006F1FH ** 163FH 0083H 006C0AH ** 213FH 0073H 006588H * 423FH 0086H 0069F7H * 543FH 009BH 0070F5H ** 653FH 00ABH 00744BH *** 0001H 0001H 00E8C4H ******************* 0002H 0002H 00B492H ************ 0004H 0003H 0080E2H ***** 0005H 0004H 006B50H ** 0006H 0005H 006B11H ** 0001H 0001H 00B8FAH ************* 0002H 0002H 00DD9CH ****************** 0004H 0003H 0088A9H ****** 0005H 0004H 006BE8H ** 0006H 0005H 006973H * 0023H 0001H 011B18H ************************** 002AH 0002H 0099B6H ******** 0031H 0003H 006A09H * 0038H 0004H 0068CEH * 003FH 0005H 006CF5H ** 0006H 0005H 006B11H ** 0006H 0005H 006973H * 0038H 0004H 0068CEH * 1123H 0014H 01FEFFH *********************************************************** 1:OSA 1:OSD 23:IW L25 taguchi sweep to reduce sweeping samples. Too time consuming If performing full permutation sweep. Average by OSA Average by OSD Average by IW Taguchi selection Viterbi Margin Metrix (VMM). Treat VMM as error rate, lower value means better signal.
  • 17. 17 Taguchi tub (1) Tub : TAGU_S Default Dac : 2DH Selected Dac : 38H DAC COUNT VALUE 1123H 0014H 01FEFFH *********************************************************** 2223H 001CH 01D113H **************************************************** 4423H 0030H 00E2BCH ****************** 5523H 003CH 0070FAH ** 6623H 004AH 0063B1H * 122AH 002CH 014D1BH ********************************* 242AH 0039H 007CD5H **** 452AH 004CH 006373H * 562AH 0059H 00698BH * 612AH 0042H 0069A0H * 1431H 0049H 006BAAH ** 2531H 0054H 006AC8H ** 4631H 0069H 006D57H ** 5131H 0053H 0067CCH * 6231H 0060H 00669BH * 1538H 0065H 00680AH * 2638H 0072H 0068A2H * 4138H 0066H 0066F0H * 5238H 0073H 00654EH * 6438H 0088H 006F1FH ** 163FH 0083H 006C0AH ** 213FH 0073H 006588H * 423FH 0086H 0069F7H * 543FH 009BH 0070F5H ** 653FH 00ABH 00744BH *** 0001H 0001H 00E8C4H ******************* 0002H 0002H 00B492H ************ 0004H 0003H 0080E2H ***** 0005H 0004H 006B50H ** 0006H 0005H 006B11H ** 0001H 0001H 00B8FAH ************* 0002H 0002H 00DD9CH ****************** 0004H 0003H 0088A9H ****** 0005H 0004H 006BE8H ** 0006H 0005H 006973H * 0023H 0001H 011B18H ************************** 002AH 0002H 0099B6H ******** 0031H 0003H 006A09H * 0038H 0004H 0068CEH * 003FH 0005H 006CF5H ** 0006H 0005H 006B11H ** 0006H 0005H 006973H * 0038H 0004H 0068CEH * Average by each OSA setting Taguchi selection: IW : 0x38; OSA 0x6; OSD 0x6 Avg by OSA VMM(decimal) VMM (hex) 1 59588.8 E8C4 2 51284.5 C854 4 34461.5 869D 5 27111.75 69E7 6 26818.75 68C2 Min value is selected
  • 18. 18 Head1 Zone 2: Taguchi and 1-D sweeping (1) Tub : TAGU_S Default Dac : 2DH Selected Dac : 38H DAC COUNT VALUE 1123H 0014H 01FEFFH *********************************************************** 2223H 001CH 01D113H **************************************************** 4423H 0030H 00E2BCH ****************** 5523H 003CH 0070FAH ** 6623H 004AH 0063B1H * 122AH 002CH 014D1BH ********************************* 242AH 0039H 007CD5H **** 452AH 004CH 006373H * 562AH 0059H 00698BH * 612AH 0042H 0069A0H * 1431H 0049H 006BAAH ** 2531H 0054H 006AC8H ** 4631H 0069H 006D57H ** 5131H 0053H 0067CCH * 6231H 0060H 00669BH * 1538H 0065H 00680AH * 2638H 0072H 0068A2H * 4138H 0066H 0066F0H * 5238H 0073H 00654EH * 6438H 0088H 006F1FH ** 163FH 0083H 006C0AH ** 213FH 0073H 006588H * 423FH 0086H 0069F7H * 543FH 009BH 0070F5H ** 653FH 00ABH 00744BH *** 0001H 0001H 00E8C4H ******************* 0002H 0002H 00B492H ************ 0004H 0003H 0080E2H ***** 0005H 0004H 006B50H ** 0006H 0005H 006B11H ** 0001H 0001H 00B8FAH ************* 0002H 0002H 00DD9CH ****************** 0004H 0003H 0088A9H ****** 0005H 0004H 006BE8H ** 0006H 0005H 006973H * 0023H 0001H 011B18H ************************** 002AH 0002H 0099B6H ******** 0031H 0003H 006A09H * 0038H 0004H 0068CEH * 003FH 0005H 006CF5H ** 0006H 0005H 006B11H ** 0006H 0005H 006973H * 0038H 0004H 0068CEH * (2) Tub : OSAMPS Default Dac : 6H Selected Dac : 1H DAC COUNT VALUE 0001H 0066H 007FAFH * 0002H 006EH 0080C8H *** 0003H 0076H 0089FFH **************************** 0004H 007FH 008CE2H ************************************ 0005H 0088H 008F6EH ****************************************** 0006H 0092H 00955BH ********************************************************** Default OSD (from Taguchi): 6H Default IW (from Taguchi): 38H OSA = 1H OSD = 6H IW = 38H
  • 19. 19 Head1 Zone 2 Writer TUBs (1) Tub : TAGU_S Default Dac : 2DH Selected Dac : 38H DAC COUNT VALUE 1123H 0014H 01FEFFH *********************************************************** 2223H 001CH 01D113H **************************************************** 4423H 0030H 00E2BCH ****************** 5523H 003CH 0070FAH ** 6623H 004AH 0063B1H * 122AH 002CH 014D1BH ********************************* 242AH 0039H 007CD5H **** 452AH 004CH 006373H * 562AH 0059H 00698BH * 612AH 0042H 0069A0H * 1431H 0049H 006BAAH ** 2531H 0054H 006AC8H ** 4631H 0069H 006D57H ** 5131H 0053H 0067CCH * 6231H 0060H 00669BH * 1538H 0065H 00680AH * 2638H 0072H 0068A2H * 4138H 0066H 0066F0H * 5238H 0073H 00654EH * 6438H 0088H 006F1FH ** 163FH 0083H 006C0AH ** 213FH 0073H 006588H * 423FH 0086H 0069F7H * 543FH 009BH 0070F5H ** 653FH 00ABH 00744BH *** 0001H 0001H 00E8C4H ******************* 0002H 0002H 00B492H ************ 0004H 0003H 0080E2H ***** 0005H 0004H 006B50H ** 0006H 0005H 006B11H ** 0001H 0001H 00B8FAH ************* 0002H 0002H 00DD9CH ****************** 0004H 0003H 0088A9H ****** 0005H 0004H 006BE8H ** 0006H 0005H 006973H * 0023H 0001H 011B18H ************************** 002AH 0002H 0099B6H ******** 0031H 0003H 006A09H * 0038H 0004H 0068CEH * 003FH 0005H 006CF5H ** 0006H 0005H 006B11H ** 0006H 0005H 006973H * 0038H 0004H 0068CEH * (2) Tub : OSAMPS Default Dac : 6H Selected Dac : 1H DAC COUNT VALUE 0001H 0066H 007FAFH * 0002H 006EH 0080C8H *** 0003H 0076H 0089FFH **************************** 0004H 007FH 008CE2H ************************************ 0005H 0088H 008F6EH ****************************************** 0006H 0092H 00955BH ********************************************************** (3) Tub : OSDURS Default Dac : 6H Selected Dac : 4H DAC COUNT VALUE 0001H 0051H 00851DH ********************************************************** 0002H 0055H 00854DH *********************************************************** 0003H 005AH 007D84H * 0004H 005EH 007E3DH ****** 0005H 0062H 007F6CH *************** 0006H 0066H 007EEDH *********** Default OSA (from 1-D OSA): 1H Default IW (from Taguchi): 38H
  • 20. 20 Head1 Zone 2 Writer TUBs (1) Tub : TAGU_S Default Dac : 2DH Selected Dac : 38H DAC COUNT VALUE 1123H 0014H 01FEFFH *********************************************************** 2223H 001CH 01D113H **************************************************** 4423H 0030H 00E2BCH ****************** 5523H 003CH 0070FAH ** 6623H 004AH 0063B1H * 122AH 002CH 014D1BH ********************************* 242AH 0039H 007CD5H **** 452AH 004CH 006373H * 562AH 0059H 00698BH * 612AH 0042H 0069A0H * 1431H 0049H 006BAAH ** 2531H 0054H 006AC8H ** 4631H 0069H 006D57H ** 5131H 0053H 0067CCH * 6231H 0060H 00669BH * 1538H 0065H 00680AH * 2638H 0072H 0068A2H * 4138H 0066H 0066F0H * 5238H 0073H 00654EH * 6438H 0088H 006F1FH ** 163FH 0083H 006C0AH ** 213FH 0073H 006588H * 423FH 0086H 0069F7H * 543FH 009BH 0070F5H ** 653FH 00ABH 00744BH *** 0001H 0001H 00E8C4H ******************* 0002H 0002H 00B492H ************ 0004H 0003H 0080E2H ***** 0005H 0004H 006B50H ** 0006H 0005H 006B11H ** 0001H 0001H 00B8FAH ************* 0002H 0002H 00DD9CH ****************** 0004H 0003H 0088A9H ****** 0005H 0004H 006BE8H ** 0006H 0005H 006973H * 0023H 0001H 011B18H ************************** 002AH 0002H 0099B6H ******** 0031H 0003H 006A09H * 0038H 0004H 0068CEH * 003FH 0005H 006CF5H ** 0006H 0005H 006B11H ** 0006H 0005H 006973H * 0038H 0004H 0068CEH * (2) Tub : OSAMPS Default Dac : 6H Selected Dac : 1H DAC COUNT VALUE 0001H 0066H 007FAFH * 0002H 006EH 0080C8H *** 0003H 0076H 0089FFH **************************** 0004H 007FH 008CE2H ************************************ 0005H 0088H 008F6EH ****************************************** 0006H 0092H 00955BH ********************************************************** (3) Tub : OSDURS Default Dac : 6H Selected Dac : 4H DAC COUNT VALUE 0001H 0051H 00851DH ********************************************************** 0002H 0055H 00854DH *********************************************************** 0003H 005AH 007D84H * 0004H 005EH 007E3DH ****** 0005H 0062H 007F6CH *************** 0006H 0066H 007EEDH *********** (4) Tub : IW_SCE Default Dac : 37H Selected Dac : 39H DAC COUNT VALUE 0023H 001EH 01C44CH ********************************************************** 0025H 0024H 01A407H ***************************************************** 0027H 002AH 01741BH ********************************************* 0029H 0030H 013324H *********************************** 002BH 0036H 00F52FH ************************* 002DH 003CH 00A611H ************ 002FH 0043H 008DE6H ******** 0031H 0049H 00772DH **** 0033H 0050H 00703FH *** 0035H 0057H 0065ABH * 0037H 005EH 0066F9H * 0039H 0065H 006328H * 003BH 006CH 0065E4H * 003DH 0073H 0061D3H * 003FH 007BH 006259H * Default OSA (from 1-D OSA): 1H Default OSD (from 1-D OSD): 4H  IW selected = median of 5 min value.
  • 21. 21 Trend of good settings (1) Tub : TAGU_S Default Dac : 2DH Selected Dac : 38H DAC COUNT VALUE 1123H 0014H 01FEFFH *********************************************************** 2223H 001CH 01D113H **************************************************** 4423H 0030H 00E2BCH ****************** 5523H 003CH 0070FAH ** 6623H 004AH 0063B1H * 122AH 002CH 014D1BH ********************************* 242AH 0039H 007CD5H **** 452AH 004CH 006373H * 562AH 0059H 00698BH * 612AH 0042H 0069A0H * 1431H 0049H 006BAAH ** 2531H 0054H 006AC8H ** 4631H 0069H 006D57H ** 5131H 0053H 0067CCH * 6231H 0060H 00669BH * 1538H 0065H 00680AH * 2638H 0072H 0068A2H * 4138H 0066H 0066F0H * 5238H 0073H 00654EH * 6438H 0088H 006F1FH ** 163FH 0083H 006C0AH ** 213FH 0073H 006588H * 423FH 0086H 0069F7H * 543FH 009BH 0070F5H ** 653FH 00ABH 00744BH *** 0001H 0001H 00E8C4H ******************* 0002H 0002H 00B492H ************ 0004H 0003H 0080E2H ***** 0005H 0004H 006B50H ** 0006H 0005H 006B11H ** 0001H 0001H 00B8FAH ************* 0002H 0002H 00DD9CH ****************** 0004H 0003H 0088A9H ****** 0005H 0004H 006BE8H ** 0006H 0005H 006973H * 0023H 0001H 011B18H ************************** 002AH 0002H 0099B6H ******** 0031H 0003H 006A09H * 0038H 0004H 0068CEH * 003FH 0005H 006CF5H ** 0006H 0005H 006B11H ** 0006H 0005H 006973H * 0038H 0004H 0068CEH *  Taguchi selects: 0x6 OSA; 0x6 OSD; 0x38(56) IW  1-D sweep select OSA 0x1; OSD 0x4; IW 57
  • 22. 22 Messages from Taguchi tub  Taguchi select IW 0x38, OSA 0x6, OSD 0x6  Taguchi sweep prefers higher OSA/OSD for optimum IW  1-D sweep select OSA 0x1; OSD 0x4; IW 57
  • 23. 23 Saturation trend in Taguchi tub  Taguchi select IW 0x38, OSA 0x6, OSD 0x6  Taguchi sweep prefers higher OSA/OSD for optimum IW  1-D sweep select OSA 0x1; OSD 0x4; IW 57
  • 24. Writer optimization results vs big ARCO results KhengKait Channel Hardware Result comparison WD CONFIDENTIAL
  • 25. Taguchi tub  Taguchi selects IW 0x38, OSA 0x6, OSD 0x6  Taguchi sweep prefers higher OSA/OSD for optimum IW  1-D sweep selects IW 0x39; OSA 0x1, OSD 0x4  Taguchi trend is matching with Big ARCO
  • 26. Taguchi tub  Taguchi select IW 0x38, OSA 0x6, OSD 0x6  Taguchi sweep prefers higher OSA/OSD for optimum IW  1-D sweep select OSA 0x1; OSD 0x4; IW 57 IW 56; OSD 6; sweep OSA
  • 27. 27 Taguchi tub  Taguchi sweep prefers higher OSA/OSD for optimum IW  1-D sweep select OSA 0x1; OSD 0x4; IW 57 4 IW 56; OSA 1; sweep OSD
  • 28. 28 Taguchi tub  Taguchi sweep prefers higher OSA/OSD for optimum IW  1-D sweep select OSA 0x1; OSD 0x4; IW 57 4 OSD4; OSA 1; sweep IW
  • 29. Reason why BigARCO recommend settings is Fail KhengKait Channel Hardware Explain via illustration & XMMS data analysis WD CONFIDENTIAL
  • 30. 30 Big ARCO recommend settings  still possible for 1-D sweep to choose lower (bad) OSA/OSD settings
  • 31. 31 List out GIDs used in TaKO and FullARCO Zone information (OD, MD, ID, Rsv)  OD 1, MD 10, ID 20, reserve  Table: 8 = cold, 9 = amb, 10= hot WD Confidential
  • 32. 32 XMMS: IW, OSA & OSD in TaKO  New setting: saturated  Old setting: bias to higher IW OSA OSD IW  New setting: possible to choose lower (bad) OSA/OSD combination
  • 33. 33 TaKO results  Old settings has more poor tilt end than new settings
  • 34. 34 TaKO results  Old settings has more poor tilt end than new settings
  • 35. 35 TaKO result analysis  Old settings has more poor tilt end than new settings  Inspect from average perspective, new and old settings are comparable (since higher IW/OSA/OSD) are able to obtain saturated result.  only applicable to ambient but hot temperature.  1-D sweeping causing big ARCO recommend settings not suitable to use writer optimization unless the following is changed:  (Code change)Optimization sequence changed to IW  OSD  OSA  Replace 1-D optimization with 2-level Taguchi or other equivalent design.
  • 36. TaKO results  EM at OD: comparable. OSA/OSD of new settings at OD are higher than MD and ID.
  • 37.  TPI/KFCI are more dominant effect in EM DC shift.  Writer parameters is just for saturated result but KFCI able to gives a big leap.
  • 38.  from another writer parameters evals(60L vs 60K), I takes same TPI/KFCI binning (less TPI/KFCI changes) of same drive, lower OSA/OSD tend to have poorer EM result.  Conclusion: with Codata with BigARCO recommend settings, it is still possible to select poor OSA/OSD settings which end up IW selects higher end settings.
  • 39. New Codata with saturated choice KhengKait Channel Hardware To illustrate the failure WD CONFIDENTIAL
  • 40. 40 Big ARCO recommend settings  Selections will always fall into saturation(good) region --> all settings are good (if not ATI)  bell-curve XMMS distribution.  Need to watch out ATI
  • 41. 41 Same drive XMMS review  JN.B.YA (baseline: old settings) vs JN.B.YN(new settings)  Quantity of drive: 46  Hypothesis/expectation: comparable result with lower count on poor tilt-end  PMR: effect of writer parameters on EM/SNR is reduced compared to LMR. Sufficient writer energy will do in order to obtain saturated SNR.  according to Marvel engineer.  Review result:  TPI/KFCI: identical/comparable  EM: comparable with lower poor tilt-end distribution
  • 42. 42 Same drive XMMS review: TaKO  TPI/KFCI: identical/comparable  EM: comparable with new settings slightly better
  • 43.  Comments only applied for new settings  OSA: bias to lower mid range (5~10)  not an signature of saturation  OSD: bias to median 10 ( sweep range 5~15, median 10=)  normal distribution = signature of saturation.  IW: normal distribution = signature of saturation.  Conclusion: results look good in overall, need to monitor OSA  IMHO, less chance cos it is covered by OSD and IW.  It is always a plus if there is a way to lowering down IW (green tech).
  • 44.  There is one outlier at new settings consistently.  Need to know the SN for checking.
  • 45. 45 Same drive XMMS review: post TaKO  EM: comparable
  • 46. 46 Same drive XMMS review: post TaKO  Same comment as in TaKO
  • 47. FA: 0 OTRC Failure KhengKait Channel Hardware To illustrate the failure WD CONFIDENTIAL
  • 48. 48 Failure Analysis - samples  Backgrounds: new head M11P is introduced in F2 & F3 build. Most failures are writer parameters related.  Failures type: EM combo, AC, 0 OTRC, DLG.  Symptom: OSA/OSD selection are in contrast with Taguchi selection  Taguchi: clean tub and preferring higher OSA/OSD. low OSA/OSD yields poor result.  1-Dimension OSA/OSD: saturated and values selected << Taguchi selection  1-dimension IW: clean bath tub.  Ambient performance is ok with low OSA/OSD but degrade in hot (SNR degraded)  Bench FA: increasing OSA/OSD able to pass the failure  Big ARCO result: prefers higher OSA/OSD
  • 49. 49 0 OTRC failure Run at hot  Amb performance is good.  Hot performance is poor
  • 51. 51 Conclusion  XMMS results look good. New settings are OK to go.  Things to watch-out: BI results and OSA optimization.