Thursday, July 2, 2015

Tpi calibration Specification



Tpi calibration
Specification
This test will be determine the tracks per inch (TPI) setting for each head of the drive under test
This test is considered as (drive validation test) dvt test
The actual VTPI test isnnot steps like preamp and jog- but it basically perform sector reads and computer error rates
The error rate is based on each bit performance
First collect all information and data necessary to the test-the estimated testing time per head is 20 minutes

Its sequence

3.1 Test algorithm

Preamp gain calibration
Set Kilo Flux Change per Inch (KFCI) to 1, set TPI to 1. The flux change refers to the number of magnetic flux change to the tangential direction of media. Both KFCI and TPI have tables which contain the number of flux changes and tracks respectively. In the table, number 1 has the largest TPI value. As the test goes on, the number of tracks per inch decreases.

2T jog optimization

Set TPI from 1 to the number of cases possible in the table mentioned above and do the following:
a.       FIR, Bias, Iwrite, WPC, etc.
b.      Read and measure error rates using sector mode and “manually” count errors.

Decide which TPIs to set based on error rates and thresholds. Before starting test, a target error rate is assigned. This is defined in input data parameter 12 and 13. Starting from the largest possible number of tracks per inch, the TPI test runs until the error delta gets lower than the threshold value.

Save all debug and results to disk. 

3.2 Test Structure Initialization

All structures used during this test will be set to initialized values prior to any collection of data. 

3.3 Input Data

Data is passed to the test through the SPT/user interface. The structure for the data is defined in section 4. 

3.4 Starting the test

Upon start-up control can be passed to the VTPI test through the Process Self Test (PST) sequencer table or through the Vendor Specific Command (VSC) Execute File. Upon the conclusion of the VTPI test control reverts back to the PST sequencer table or exits if it’s started via the VSC command.

3.5 Errors

This test is designed to continue as long as possible in the event of an error. Only fatal errors, errors that would make the test data or results meaningless, will result in immediate exit from the test without the setting of the VTPI. 

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