General MFG terms Flashcards
RDP
In-field depop (Lane).
Repurposing Depopulation - The purpose of Repurposing Depopulation is to give the host the ability to logical depopulate a head on the drive. For example, if a specific head/media begins reporting a status that indicates the performance is not within manufacturer’s specification limit the host my choose to remove all read/write operations from that head by executing this command.
3 mechanisms to depopulate heads
- Pre-Rsvd Head Depopulation
- Post-Rsvd Head Depopulation
- Customer Initiated Head Depopulation via Standard “Repurposing Depopulation” (RDP) command
(From Lane’s email)
Pre-Rsvd Head Depopulation
– This is the existing common practice (think 2-head depopulated drives)
– Drive is freshly manufacturing to a fixed number of heads.
Post-Rsvd Head Depopulation
– AKA “Inline Depop” or “Waterfall Depop” : New for CCB8, WIP as of 5/10/2020
– Heads may be depopulated at any point in the process after pre-rsvd (Function Test, SRST, Final, Featuring)
Customer Initiated Head Depopulation via Standard “Repurposing Depopulation” (RDP) command
– Feature introduced in SMR7 (based on DLD existed in CCB6P), lightly used
– In CCB8, the ability for a customer to repopulate a head will be added.
Four head mapping domains
- Physical heads (head stack, set during build time)
- RA Heads (Logical mapping of heads used when RA1 area is formatted, set during Format Reserved)
- MFG Heads (Logical mapping of heads post-mfg, set during Featuring)
- Logical Heads (Logical mapping of heads used on the current format, sed during in-field depop - RDP)
Strong types have been defined for each of these domains. (Format::PhysicalHead, Format::RaHead, Format::MfgHead, Format::LogicalHead).
RID
Reserved area Internal Data; “Binary file stored on media and contains drive customization data. Data stored in reserved area is required to spin up drive and enable read write capability.”
FID
Flash Internal Data
Mutate
Changes CMR/SMR on an XMR drive
ACC
Achievable Capacity Capability
It refers to a metric that comes from manufacturing - each drive optimizes settings, TPI/BPI to maximize the number of bits that can be stored.
Mode 4 Prep
(or “Reserve Area Prep”)
Means “I have verified my ability to get all the data from the flash so that I can access the reserve area” (Rebekah)
Mode 5 Prep
(or “User Area Prep”)
Reading and writing the reserve area to do user operations (Rebekah)
.. Then you can do CSO, etc.
Function Test (FT)
TPI/BPI is selected (Brian)
SRST
Self Run Stress Test
It is activated with drive micro code and it performs surface analysis, format, read/write test; old name for on-drive test code. (dictionary).
Defect mapping, reserve area (Brian)
Final
pack read/write (Brian)
Featuring
HDD microcode download and customization process; one of the last steps in HDD manufacturing process where drive is loaded with specific customer code. (dictionary).
What the dynamic config team does. (Brian)
OQA
Outgoing Quality Assessment; Quality sample and test for each shipment (dictionary)
MFG steps
Build –> FT –> SRST –> Final –> Featuring –> OQA
UFO
Unified Format Optimization.
It is a manufacturing command that optimizes TPI and KFCI for optimal HDD yield. The goal of the project is to incorporate TAKO (WD-L) and UAF (HGST-L) manufacturing commands, and more importantly, to deliver a better design that enables future HDD programs to achieve optimal ACC and HDD yield. (UFO algorithm Confluence)
KFCI
Kilo (thousand) flux changes per inch (dictionary)
along a track
BPI or KBPI
Bits or kBits per inch (along a track)
KBPI = KFCI x code rate
ADC
Areal Density Capability
= BPI x TPI
Pre-Amp
The Pre-Amp (or known as AE or arm-electronics) is the chip that directly interfaces with the head for writing and reading data.
Pre-Amp general functions
- Magnify the weak signal from the reader
- Control the fly height
- Drive the write current
RW Channel
The channel is integrated in the SOC, and the overall goal is to write and read the data at the highest possible areal density.
RW Channel Input and output
Input: 2-level (high/low) write current shape (representing the 1s and 0s)
Output: Noise read back waveform (the signal that will be turned into 1s and 0s)
RW Channel read process
Read: the channel processes the signal (adjusting the signal amplitude, waveform, band limit the high frequency noise, ADC, equalization, decode, etc.) directly from the pre-amp
The read process includes:
- an analog front end (gets the signal from the pre-amp, goes through a variable gain amplifier, asymmetry correction, low-pass filter, etc.),
- and then a digital back end (equilizer, SOVA (soft-output Viterbi Algorithm), LDPC (Low Density Parity Check code), etc.)
RW Channel write process
Write: the channel processes the signal before sending to the writer
The write process gets the 4k sector bits as input, then
- appends CRC (Cyclic redundancy Check code
- Modulation Encoder
- LDPC (Low Density Parity Check) encoder
- Precomp
then outputs to the pre-amp write driver
Key prerequisites to read/write
- Reader and writer offset (Mjog)
- Fly height (the slider needs to be close to the disk)
- Proper timing (use servo signal, and don’t erase it)
- Write current (proper write wave shape)
- Other channel/pre-amp setup (zone-dependent and independent setup)
MCCB
Manufacturing Command Command Block - Command block for MfgCmd
Mjog
reader and writer offset; the position is only determined by the reader for both read and write operations
DTM
DTM stands for Drive Test Module. It is an HDD test firmware responsible for calling a sequence of manufacturing commands (MfgCmds) with particular MCCB settings.
MCSB
The MCSB Table is a Common Header for all Manufacturing Command Status Blocks
DTM’s role with MCSBs (Mfg cmd status blocks)
DTM also handles collection and reporting of the MCSBs from those MfgCmds and passing information back up to the host.
DTM Legacy Commands
DTM also contains logic for commands and functionality that are not encapsulated by MfgCmds, these are known as DTM Legacy Commands (or sometimes SRST legacy commands).
DTM is made up of two pieces
code and configuration data
MFGDs
The DTM data is compiled into images known as “MFGDs.”
Each individual sequence is compiled into its own MFGD file.
A complete test process is made up of one or more MFGD sequences.
MFGDs are the compiled data structure defined by a collection of XML files that define these four things:
- The sequence of MfgCmds to be run (the sequence can be a simple static sequence or controlled by selectors)
- The MCCB settings for the individual commands that make up that sequence (MCCB settings can also be simple and static or controlled via selectors)
- A collection of limits that will be tested against the MCSBs returned by the MfgCmds (these limits make up the bulk of the specifications applied against all drives that go through the factory test process)
- A limited set of environmental and configuration settings for things like “record log size”, “preferred temperature”, and more.
DTM code is the C++ logic mainly responsible for:
- Running the generic sequences from the loaded MFGD
- Constructing the MCCB structures
- Processing the MCSB data and comparing those outputs to the specifications from the MFGD
- Managing writing to and from the firmware FIDs and RIDs
Atlas
Niaraga based GUI tool that access/modify DTM XML files.
The easiest way to adjust DTM sequence and settings is using the Atlas tool. Atlas is a Niagara extension and can be launched by hitting the “Atlas” button in the GUI.
MUEC
Manufacturing Unit Error Code
GTM Mfg Cmd
Gate Timing Mfg Cmd
We learn where our writer is relative to our reader.
WCS
Writable Control Store. It’s like a time state machine.
Servo sync mark found, start the time state machine. It asserts the servo gate so you start reading the information, it counts down the seconds, and then it knows it should be more or less be hitting the next servo wedge. It opens the servo gate, looks for the sync mark, and when it hits it, it starts the state machine again.
UFO
Unified Format Optimization - a manufacturing command that optimizes TPI and KFCI for optimal HDD yield.
AST
adjusted servo tracks
ADT
adjusted data tracks
