Hard Disk Repair | DataRecoveryUnion.com

Keys and keycodes and console

dumpkeys        Dump keyboard translation tables.
getkeycodes        Print kernel scancode-to-keycode mapping table.
lesskey        Specify key bindings for less.
loadkeys        Load keyboard translation tables.
psfaddtable        Add a unicode character table to a console font.
psfgettable        Extract the embedded Unicode character table from a console font.
psfstriptable        Remove the embedded Unicode character table from a console font.
resizecons        Change kernel idea of the console size.
setkeycodes        Load kernel scancode-to-keycode mapping table.

Ncurses functions

captoinfo        Convert a termcap description into a terminfo description.
clear        Clear the terminal screen.
infocmp        Compare or print out terminfo descriptions.
reset        Restore run-time parameters for session to default values.
tie        Merge or apply WEB change files.
toe        Table of terminfo entries.
tput        Initialize a terminal or query terminfo database.
tset        Terminal initialization.

CD programs

cdparanoia An audio CD reading utility.
cdrecord Record audio or data compact Disks from a master.

Other

alias        Ex:: alias dir=’ls -a’ – Effect: Makes dir list all files (no spaces next to the = sign).
bison        GNU project parser generator.
chvt        Change foreground virtual terminal.
crack        Program used to find bad passwords or crack security.
cvs        Concurrent Versions System.
deallocvt        Gets rid of unused virtual terminals.
dumpkeys        Dump keyboard translation tables.
fc         Fix command. Used to edit the commands in the current history list.
gdbm        The GNU database manager.
gpm        A cut and paste mouse server.
history        Show commands listed in the shell history (last n).
lilo        Boot management program.
mc        Visual shell for Unix like system. A file manager.
nc        A file manager.
pdksh        Public domain Korn shell.
pilot        Filesystem browser.
PS1=”Please enter a command”        Set Bash level 1 response.
PS2=”I need more information”        Set Bash level 2 response.
rcs        Recision Control system. Change RCS file attributes.
sash        Standalone shell with built in commands.
screen        Screen manager with VT100 terminal emulation.
sleep        Ex: “sleep 2” – wait 2 seconds.
tcsh        C shell with filename completion and command line editing.
unalias        Ex: “unalias dir” – Effect: Removes the alias dir.
units        Unit conversion program.
variables

* set – Ex: set t=/temp
* unset – Ex: unset t
* echo – Ex: echo $t

zsh The Z shell.
ttysnoop A program that comes with some systems that lets the administrator to snoop on the user’s terminals.

Hard Disk Repair

Linux Network Management

DATARECOVERYUNION.COM16 years ago12 years ago06 mins

Names

dnsdomainname
Show the systems DNS domain name

domainname
Show or set the systems domain name

hostname
Used to show or set the name of your machine for networking

nisdomainname
Show or set systems NIS/YP domain name

nodename
Show or set the systems DECnet node name

ypdomainname
Show or set the system’s NIS/YP domain name

Network setup and commands

arp
This program lets the user read or modify their arp cache.

dig(1)
Send domain name query packets to name servers for debugging or testing.

finger
Display information about the system users.

ftp
File transfer program.

ifconfig
Configure a network interface.

ifdown
Shutdown a network interface.

ifup
Brings a network interface up. Ex: ifup eth0

ipchains
IP firewall administration used to set input, forward, and output rules.

netconf
A GUI interactive program to let you configure a network on Redhat systems.

netconfig
Another GUI step by step network configuration program.

netstat
Displays information about the systems network connections, including port connections, routing tables, and more. The command “netstar -r” will display the routing table.

nslookup
Used to query DNS servers for information about hosts.

pftp
Same as ftp.

ping
Send ICMP ECHO_REQUEST packets to network hosts.

portmap
DARPA port to RPC program number mapper. Must be running to make RPC calls.

rarp
Manipulate the system’s RARP table.

rcp
Remote file copy. Copies files between two machines.

rexec
Remote execution client for an exec server. The host uses the rexecd server.

ripquery
Query RIP gateways. Request all routes known by an RIP gateway by sending an RIP request.

rlogin
Starts a terminal session on a remote host.

route
Show or manipulate the IP routing table.

rsh
Executes command on remote host.

rup
Displays summary of current system status of a remote host or all hosts on the network.

ruptime
Show host status of local machines.

rwhod
System status server, maintains database used by rwho and ruptime.

showmount
Show mount information for an NFS server.

tcpd
Access control facility for internet services. Can be set up to monitor requests for Telnet, finger, ftp, exec, rsh, rlogin, tftp, talk, comsat. It filters access for these requests.

tcpdchk
Tcp wrapper configuration checker.

tcpdump
Dump traffic on a network. Prints out headers of packets that match the boolean expression.

tcpdmatch
Predicts how the tcp wrapper will handle a specific request for a service.

Telnet
User interface to the TELNET protocol, setting up a remote console session.

traceroute
Print the route that packets take to the specified network host.

ipx_configure
Tool to setup Netware access.

ncpmount
Netware filesystem mounting program.

nprint
Novell print command.

pqlist
Netware printer list for a given server.

pserver
Netware print server.

slist
Netware server list.

Communications commands (includes mail)

biff
Notifies the system if mail arrives and who it is from.

comsat
Biff server to receive reports of incoming mail.

expire
Used to purge old news articles.

elm
Electronic mail.

ftp
File transfer protocol.

mailx
Berkley mail program.

metasend
Interface for sending non-text mail.

nn
Net news.

pine
Program for internet news and e-mail, Can send documents, graphics, local & remote messages.

sendmail
A popular Unix, Linux mail message transfer agent.

smail
A popular mail message transfer agent which is easier to set up than sendmail.

talk
Lets two parties talk simultaneously.

telnet
Allows a user to have a login session across a network on a remote host.

tin
Net news reader.

write
Allows users to directly interact with other users via terminal number (one way at a time).

Hard Disk Repair

Linux Help Commands, Job Management, Process management

DATARECOVERYUNION.COM16 years ago4 years ago24 mins

1. Linux Help Commands

apropos        apropos keyword – Show all commands with the keyword in their description. The same as the “man -k” command.
help        Bash shell help for the bash builtin command list. The help command gets help for a particular command.
man        Get help from the manual for a command.
man        man -k keyword – Show all commands with the keyword in their description
“man 2 kill” – Display page 2 of the kill command
manpath        Determine user’s searchpath for manpages.
info        Documentation on Linux commands and programs similar to the man pages but navigation is organized different.

2. Linux Job Management

at        Similar to cron but run only once.
atq        Lists the user’s pending jobs. If the user is the superuser, everybody’s jobs are listed.
atrm        Deletes at jobs.
atrun        Run jobs queued for later execution
batch        Executes commands when system load levels drop below 0.8 or value specified in atrun invocation.
cron        A deamon used to set commands to be run at specific times. Starts the commands in the crontab file. Used to clean up temporary files periodically in the /var/tmp and /tmp directories.
nice        Run a program with modified scheduling priority.
nohup        Run a command immune to hangups, with output to a non-tty.
watch       Execute a program periodically showing output full screen.

3. Linux Process management

bg        Starts a suspended process in the background
fg         Starts a suspended process in the foreground
gitps        A graphical process viewer and killer program.
jobs        Lists the jobs running
kill        Ex: “kill 34” – Effect: Kill or stop the process with the process ID number 34.
killall        Kill processes by name. Can check for and restart processes.
pidof        Find the process ID of a running program
ps        Get the status of one or more processes. Options:

* u (more info)
* a (see all)
* -l (technical info)

Meanings:

* PPID-parent process ID
* PID-process ID

ps ax |more to see all processes including daemons
pstree        Display the tree of running processes.
sa        Generates a summary of information about users’ processes that are stored in the /var/log/pacct file.
skill        Report process status.
snice        Report process status.
top        Display the processes that are using the most CPU resources.
CTRL-C        Kills the current job.
&         At the end of the command makes it run in the background.

Hard Disk Repair

Hard Drive Firmware Update/Recover by Yourself

DATARECOVERYUNION.COM16 years ago4 years ago15 mins

We know that up to 60% of hard disk drive failures are caused by firmware corruption. Just a little damage is enough to render a hard drive totally unusable. In such cases hard drive becomes inaccessible and sometimes can completely disappear from the system.

“For example, a hard drive can lose its parameters such as device model number and capacity. When it happens, there is no access to partitions and files. In most cases the problem is caused by firmware damage.”

What is firmware?
Firmware is software which is embedded in a piece of hardware. You can think of firmware simply as “software for hardware”.

Where the firmware stores?
Modern disks normally have their firmware codes located on data platters and also the PCB board.

Why firmware is so important?
Without the firmware, no communication will be possible between the PC system and the hard disk. If the firmware area is corrupted, the drive will appear to have failed even all the electrical and mechanical components are still fully functional.

The symptoms of firmware corruption:
1. Drive powers up, but is not recognized /defected by the computer
2. Drive powers up, but is recognized wrongly, sometimes with nonsensical characters, manufacture alias (Such as N40p for Maxtor 6Y and etc ;);
3. Drive freezes during booting up;
4. Drive detect in wrong Capacity, such as 80 GB detected as 1Mb;
5. S.M.A.R.T error;
6. Drive is locked by human error; such as Hitachi hard drive by a drop; it is a self protection method of HDD design;
7. Drive clicking ;( it can be caused by firmware too, the heads try to read the SA on platters and can not positing)

How to update/recover hard drive firmware by yourself?

In fact, in many drives the firmware can be updated under software control, very much the same way that a flash BIOS works. Unlike the system BIOS, this is only very rarely done, when a particular sort of problem exists with the firmware logic that can be fixed without requiring a physical hardware change. You can check the drive manufacturer’s web site for more details. For Example: Seagate Barracuda 7200.11 Command Queuing

If you don’t want to spend a lot of money on the expensive data recovery tools, such as PC3000 or HD Doctor Suite, how do you recover hard drive firmware corruption? Here are some free firmware recover tools , hope them can help you:

A-FF Repair Station

Diagnoses the Firmware Area and hard drive mechanics and displays a short summary of hard drive’s health;
Reads the Firmware Area;
Extracts and analyzes all firmware structures;
Rebuilds damaged parts and writes the firmware back to the drive.

All the operation is absolutely safe to the data (partitions and files) and takes no more than 20 minutes.

Maxtor Firmware Repair 2.0
Aiming at solution for typical firmware malfunction of Maxtor 541DX (2B020H1 2B010H1), which may manifest itself as follows:

HDD is not identified or identified by its factory alias “Maxtor Athena”;
HDD starts the motor and then hangs.

Seagate Firmware Repair 5.0
Aiming at one-key solution towards typical firmware malfunction of Seagate Barracuda VII drives, which may manifest itself as follows:

HDD is not identified or identified incorrectly;
HDD starts the motor and then hangs.

Please share your ideas here!

Hard Disk Repair

Avoiding the assignment of duplicate MAC addresses to network interface devices (Part 2)

DATARECOVERYUNION.COM16 years ago12 years ago07 mins

8. The method according to claim 7, further comprising the copy step of controlling to copy data stored in the temporary MAC address file to the MAC address file when an abnormality is determined to occur in the MAC address file.

9. An MAC address management method applied to an MAC address management apparatus having storage means for storing an MAC address file comprising a plurality of MAC addresses, comprising: the transmission step of controlling to read out one MAC address from the MAC address file and transmit the MAC address to a network interface device in order to assign an MAC address to the network interface device to be connected to a network; the reception step of controlling to receive an MAC address write completion notification indicating that the transmitted MAC address has been assigned to the network interface device; the rewrite step of controlling to rewrite MAC addresses of the MAC address file except for the transmitted MAC address, in a temporary MAC address file stored in an external storage device connected to the MAC address management apparatus, when said reception step receives the MAC address write completion notification; and the delete step of controlling to delete the transmitted MAC address from the MAC address file after said rewrite step rewrites the MAC addresses in the temporary MAC address file.

10. The method according to claim 9, further comprising the copy step of copying data stored in the temporary MAC address file of the external storage device to the MAC address file when an abnormality is determined to occur in the MAC address file.

11. A computer-readable storage medium which stores an MAC address management program for controlling an MAC address management apparatus having storage means for storing an MAC address file storing a plurality of MAC addresses and a temporary MAC address file, comprising codes of: the transmission step of controlling to read out one MAC address from the MAC address file and transmit the MAC address to a network interface device in order to assign an MAC address to the network interface device to be connected to a network; the reception step of controlling to receive an MAC address write completion notification indicating that the transmitted MAC address has been assigned to the network interface device; the rewrite step of controlling to rewrite, in the temporary MAC address file, MAC addresses of the MAC address file except for the transmitted MAC address, when said reception step receives the MAC address write completion notification; and the delete step of controlling to delete the transmitted MAC address from the MAC address file after said rewrite step rewrites the MAC addresses in the temporary MAC address file.

12. The medium according to claim 11, further comprising a code of the copy step of controlling to copy data stored in the temporary MAC address file to the MAC address file when an abnormality is determined to occur in the MAC address file.

13. A computer-readable storage medium which stores an MAC address management program for controlling an MAC address management apparatus having storage means for storing an MAC address file comprising a plurality of MAC addresses, comprising codes of: the transmission step of controlling to read out one MAC address from the MAC address file and transmit the MAC address to a network interface device in order to assign an MAC address to the network interface device to be connected to a network; the reception step of controlling to receive an MAC address write completion notification indicating that the transmitted MAC address has been assigned to the network interface device; the rewrite step of controlling to rewrite MAC addresses of the MAC address file except for the transmitted MAC address, in a temporary MAC address file stored in an external storage device connected to the MAC address management apparatus, when said reception step receives the MAC address write completion notification; and the delete step of controlling to delete the transmitted MAC address from the MAC address file after said rewrite step controls to rewrite the MAC addresses in the temporary MAC address file.

14. The medium according to claim 13, further comprising a code of the copy step of copying data stored in the temporary MAC address file of the external storage device to the MAC address file when an abnormality is determined to occur in the MAC address file.

Hard Disk Repair

Avoiding the assignment of duplicate MAC addresses to network interface devices (Part 1)

DATARECOVERYUNION.COM16 years ago12 years ago011 mins

1. An MAC address management apparatus for assigning an MAC address serving as an identification number unique to a network interface device to the network interface device to be connected to a network, comprising: MAC address storage means for storing an MAC address file and a temporary MAC address file, the MAC address file comprising a plurality of MAC addresses; transmission means for reading out one MAC address from the MAC address file and transmitting the MAC address to the network interface device in order to assign an MAC address to the network interface device; reception means for receiving an MAC address write completion notification indicating that the transmitted MAC address has been assigned to the network interface device; rewrite means for rewriting, in the temporary MAC address file, MAC addresses of the MAC address file except for the transmitted MAC address when said reception means receives the MAC address write completion notification; and delete means for deleting the transmitted MAC address from the MAC address file after said rewrite means rewrites the MAC addresses in the temporary MAC address file.

2. The apparatus according to claim 1, further comprising copy means for copying data stored in the temporary MAC address file to the MAC address file when an abnormality is determined to occur in the MAC address file.

3. An MAC address management apparatus for assigning an MAC address serving as an identification number unique to a network interface device to the network interface device to be connected to a network, comprising: MAC address storage means for storing an MAC address file comprising a plurality of MAC addresses; external storage means for controlling to store a temporary MAC address file in an external storage device connected to said MAC address management apparatus; transmission means for reading out one MAC address from the MAC address file and transmitting the MAC address to the network interface device in order to assign an MAC address to the network interface device; reception means for receiving an MAC address write completion notification indicating that the transmitted MAC address has been assigned to the network interface device; rewrite means for controlling to rewrite, in the temporary MAC address file of the external storage device, MAC addresses of the MAC address file except for the transmitted MAC address when said reception means receives the MAC address write completion notification; and delete means for deleting the transmitted MAC address from the MAC address file after said rewrite means controls to rewrite the MAC addresses in the temporary MAC address file.

4. The apparatus according to claim 3, further comprising copy means for copying data stored in the temporary MAC address file of the external storage device to the MAC address file when an abnormality is determined to occur in the MAC address file.

5. An MAC address management system comprising a network interface device to be connected to a network, and an MAC address management apparatus for assigning an MAC address serving as an identification number unique to the network interface device, said MAC address management apparatus having: MAC address storage means for storing an MAC address file and a temporary MAC address file, the MAC address file comprising a plurality of MAC addresses; transmission means for reading out one MAC address from the MAC address file and transmitting the MAC address to said network interface device in order to assign an MAC address to said network interface device; reception means for receiving an MAC address write completion notification indicating that the transmitted MAC address has been assigned to said network interface device; rewrite means for rewriting, in the temporary MAC address file, MAC addresses of the MAC address file except for the transmitted MAC address when said reception means receives the MAC address write completion notification; and delete means for deleting the transmitted MAC address from the MAC address file after said rewrite means rewrites the MAC address in the temporary MAC address file, and said network interface device having: MAC address reception means for receiving the assigned MAC address from said MAC address management apparatus; write/storage means for writing and storing the MAC address; and write completion notification transmission means for transmitting the MAC address write completion notification upon completion of a write of the MAC address.

6. An MAC address management system comprising a network interface device to be connected to a network, and an MAC address management apparatus for assigning an MAC address serving as an identification number unique to the network interface device, said MAC address management apparatus having: MAC address storage means for storing an MAC address file comprising a plurality of MAC addresses; external storage means for controlling to store a temporary MAC address file in an external storage device connected to said MAC address management apparatus; transmission means for reading out one MAC address from the MAC address file and transmitting the MAC address to the network interface device in order to assign an MAC address to said network interface device; reception means for receiving an MAC address write completion notification indicating that the transmitted MAC address has been assigned to said network interface device; rewrite means for controlling to rewrite, in the temporary MAC address file of the external storage device, MAC addresses of the MAC address file except for the transmitted MAC address when said reception means receives the MAC address write completion notification; and delete means for deleting the transmitted MAC address from the MAC address file after said rewrite means controls to rewrite the MAC addresses in the temporary MAC address file, and said network interface device having: MAC address reception means for receiving the assigned MAC address from said MAC address management apparatus; write/storage means for writing and storing the MAC address; and write completion notification transmission means for transmitting the MAC address write completion notification upon completion of a write of the MAC address.

7. An MAC address management method applied to an MAC address management apparatus having storage means for storing an MAC address file storing a plurality of MAC addresses and a temporary MAC address file, comprising: the transmission step of controlling to read out one MAC address from the MAC address file and transmit the MAC address to a network interface device in order to assign an MAC address to the network interface device to be connected to a network; the reception step of controlling to receive an MAC address write completion notification indicating that the transmitted MAC address has been assigned to the network interface device; the rewrite step of controlling to rewrite, in the temporary MAC address file, MAC addresses of the MAC address file except for the transmitted MAC address when said reception step receives the MAC address write completion notification; and the delete step of controlling to delete the transmitted MAC address from the MAC address file after said rewrite step rewrites the MAC addresses in the temporary MAC address file.

Hard Disk Repair

Hard Drive Damage Types

DATARECOVERYUNION.COM16 years ago4 years ago16 mins

Data loss might also occur in small drives such as the Hitachi MicroDrive. Ontrack was unable to recover any data in the above right example.

Damage to a drive’s circuit board or defects of the drive heads occur fairly often. In both cases, to access hard drive data, a data recovery specialist will substitute the defective component with a working one. In the best case scenario you regain 100% of your data.

A so called head crash – where a write/read head physically hits the magnetic platter – is much more severe. Simply hitting your drive might cause contact, since the distance between the head and surface of drives is minimal nowadays. It is almost always safe to say that a damaged magnetized surface causes the loss of saved bits. The head might even repeatedly get caught at the area of defect, carrying off more material with each additional contact. This material will be distributed inside the drive, causing scratches or other damage. There is nothing a customer can do in case of an intense head crash, because the head is simply unable to move across the defective area any more.

Overvoltage on write/read heads causing the permanent destruction of data areas or magnetization will also result in irreversible data loss. This means the physical destruction of memory sectors, not the simple deletion of saved bits. Depending on the drive, the data recovery specialist might be able to recover some data. Recovering data from defect Hitachi drives is usually impossible, since the manufacturer does not provide any kind of firmware information. Various other products allow at least reading data from other platters.

Strange but true: even internal imbalances can cause trouble. Irregular data platter rotation due to broken bearings will result in unwanted track changes of which the drive is not aware; the result is sometimes total data hodgepodge. Bearing failure is usually the result of improper handling during transportation of the drive. The data recovery specialist will often be able to recover saved data by balancing the drive (slightly shifting and centrally rearranging the platters).

Logical mistakes do not require processing in the clean room. Usually, those mistakes are accidental misuse or deletion of files, where the drive itself has no malfunctions. Even if the problem lies within the drive, it might be a simple defective sector and nothing more severe. Every drive has defective sectors: a primary list will carry a list of bad sectors from the factory; the secondary, so called growing list, will be updated in the course of operation if more sectors become useless. This occurs rather often and is normal, but if your hard drive S.M.A.R.T. feature tells you that you better save some data fast, you’re in trouble. This often means that the growing list is full and an above-average number of sectors are dying.

Now let’s talk about an irreversible defect. Your hard drive will die if fire or another heat source heats it up beyond the Curie temperature of the magnetic material of your drive; this cases the magnetization to be neutralized completely. The Curie temperature depends on the material used in a hard drive; magneto-optical devices use with Curie point principle on purpose (heating via laser), but hard drives do not.

A user who tries to solve issues by himself can make things worse, this is the biggest problem with data recovery. According to statistics, Europeans are worse than Americans in trying to solve problems on their own. Situations also turn bad if, for example, administrators are afraid of their bosses’ reactions. Once, someone even sent a floppy drive instead of the defective hard drive – this is a clear indication of pressure placed on the person involved.

Hard Disk Repair

External Hard Disk Box

DATARECOVERYUNION.COM16 years ago4 years ago04 mins

1. An external hard disk box, used for installing a hard disk, wherein there is a first fastening hole and a second fastening hole on a bottom and two sides of the hard disk, the external hard disk box comprising: a lower cover having a receiving space for receiving the hard disk, wherein there is a first positioning portion that corresponds to the first fastening hole on the bottom surface of the receiving space; an upper cover covering the lower cover; and at least one positioning structure located on one side of the receiving space, wherein the positioning structure has a second positioning portion that corresponds to the second fastening hole.

2. The external hard disk box as claimed in claim 1, wherein the positioning structure is located on one side of the hard disk, the first positioning portion is plugged into the first fastening hole, and the second positioning portion is plugged into the second fastening hole.

3. The external hard disk box as claimed in claim 1, wherein the positioning structure is a flexible flake, the flexible flake has a side board, and the second positioning portion is located on the side board.

4. The external hard disk box as claimed in claim 1, wherein the positioning structure includes an external mask, a spring flake, and a pushing element, the external mask has a through hole that corresponds to the second positioning portion, one end of the spring flake is connected with the external mask, a second end of the spring flake is a free end and has the second positioning portion, and the pushing element is slidably located in the external mask and contacts the second end of the spring flake.

5. The external hard disk box as claimed in claim 1, wherein the positioning structure is a flexible element, one side of the flexible element bends to form a linking flake, one end of the linking flake is a free end and forms a pushing portion, and the pushing portion extends to form the second positioning portion.

6. The external hard disk box as claimed in claim 5, wherein the upper cover is slidably assembled with the lower cover, two leg columns extend from two sides of the bottom surface of the upper cover, and the leg column corresponds to the pushing portion.

7. The external hard disk box as claimed in claim 6, wherein there is a first wedged portion and a second wedged portion on the lower cover and the upper cover.

8. The external hard disk box as claimed in claim 5, wherein each of the flexible elements bends upwards to form at least one curved portion, and the curved portion pushes and contacts a bottom surface of the upper cover.

Hard Disk Repair

Background of the Magnetic disc drive head alignment system Invention

DATARECOVERYUNION.COM16 years ago12 years ago06 mins

Magnetic disc drives for recording digital data are well known to the art. In such drives it is desirable to achieve the highest recording density possible, such recording density being a function of both the number of annular tracks per radial inch of disc surface and the number of bits per inch along each track. The optimum number of tracks on the individual discs is dependent on the precision of the head positioning system and on the precision in the alignment of the various read/write heads in the disc drive. The system of the present invention provides for the precise alignment of each of the read/write heads in the disc drive so that an optimum number of tracks per radial inch of the individual discs may be achieved.

The discs incorporated into present-day disc drives are usually referred to as a disc pack, and these discs are stacked one above the other to be sensed by a plurality of magnetic read/write heads mounted in vertical alignment and positioned by a single actuator. In one type of present-day head positioning system used in disc drives, one of the heads (servo disc surface) and one disc surface are dedicated to the generation of debit position signals for an associated servo system. A plurality of servo tracks are recorded in concentric circles on the dedicated servo disc surface, and the servo head produces the debit signals which are indicative of the relative position of the servo head and the servo tracks.

For interchangeability of the disc packs, the various tracks recorded on each of the disc surfaces must be closely aligned with the pre-recorded servo tracks on the dedicated servo disc surface so that the read back of the data from each disc pack is possible on recorders other than the one on which the data was recorded.

When the servo head is held in registry with the servo tracks on the dedicated servo disc surface, and the remaining read/write heads are aligned with the servo head, the remaining heads will be properly positioned over the corresponding data tracks on other disc surfaces. As mentioned above, an objective of the present invention is to provide a system which enables the remaining magnetic heads to be precisely aligned with the servo head, so that they will all be properly positioned with respect to the data tracks on the other disc surfaces.

The normal procedure for assuring that the read/write heads are in vertical alignment is to place a disc pack into the disc drive which has pre-recorded and precisely positioned servo tracks on all the disc surfaces. Such pre-recorded servo disc packs are commercially available for use in head alignment and are usually referred to as “CE” (Customer Engineer) packs. By reading the signals from the individual heads, as the heads read the various servo tracks, and by feeding such signals to a display device, each head can be adjusted until it is in precise tracking engagement with the tracks on the surface of the corresponding disc.

The present invention, as mentioned above, provides a system for reading debit signals generated by the various heads of a disc drive, as these heads read the various servo tracks on the pre-recorded servo disc pack, and it provides digital outputs representative of any misalignments of the various heads. Each head can then be adjusted to a position at which the digital output signal for that head indicates precise alignment.

Hard Disk Repair

Magnetic disc drive head alignment system

DATARECOVERYUNION.COM16 years ago4 years ago06 mins

1. In a disc drive which includes a plurality of read/write magnetic heads and a servo magnetic head mounted for simultaneous movement by an actuator in response to a servo signal from the servo head, and in which the positions of the read/write heads are individually adjustable with respect to the servo head, a system for indicating any misalignment of the individual read/write heads as the particular head produces a cyclic position signal in response to position signals pre-recorded on alignment tracks of an alignment disc, each cycle of said cyclic position signal having a first segment with positive and negative peak amplitudes and a second segment with positive and negative peak amplitudes, the positive and negative peak amplitudes of said first and second segments being equal when the particular head is in registry with the corresponding alignment track, and the positive and negative peak amplitudes of one or the other segments decreasing when the particular head moves out of registry with the alignment rack to one side or the other thereof; said system including balanced gating circuitry having four output circuits for respectively producing four gating signals respectively timed to occur in time coincidence with respective ones of the positive and negative peak amplitudes of said first and second segments; a balanced input circuit connected to the particular head and including first and second outputs respectively applying the cyclic position signal and its complement to said gating circuitry to cause said gating circuitry to cause said gating circuitry to produce said four gating signals at the respective output circuits thereof; peak detector circuitry including four peak detector circuits respectively connected to said four output circuits of said gating circuitry to be individually gated by respective ones of said four gating signals, means connecting two of said peak detector circuits to the first output of said balanced input circuit and further means connecting the other two of said peak detector circuits to the second output of said balanced input circuit, said four peak detector circuits collectively detecting the positive and negative peak amplitudes of each of the two segments of each cycle of said position signal and providing four analog outputs corresponding thereto; and output circuitry connected to the outputs of said four peak detector circuits in said peak detector circuitry for producing an analog output signal having an amplitude corresponding to the difference between the algebraic sum of the positive and negative peak amplitudes of the first segment and the algebraic sum of the positive and negative peak amplitudes of the second segment.

2. The system defined in claim 1, in which said balanced input circuit includes a linear amplifier, and in which said system includes a summing circuit connected to said four peak detectors in said peak detector circuitry for producing an output signal representing the algebraic sum of the outputs of the four peak detector circuits, and an automatic gain control circuit connected to said summing circuit and responsive to the output thereof for producing an automatic gain control signal for said linear amplifier.

3. The system defined in claim 1, in which said gating circuitry contains a frequency-independent phase-shifting circuit so that the system may be used with a wide variety of recorded signals without adjustment.

4. The system defined in claim 1, and which includes circuitry connected to said peak detector circuitry for limiting the analog outputs thereof to a predetermined maximum.

5. The system defined in claim 1, and which includes an analog/digital converter coupled to the output of said output circuitry to convert the analog output signal therefrom into a corresponding digital signal; and a digital display device coupled to the output of the analog/digital converter.

6. The system defined in claim 1, in which said gating circuitry includes first and second comparators interconnected to provide a quadrature shift to the cyclic position signal from said balanced input circuit which is independent of frequency.