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HddSurgery BLOG

March 31st, 2015, 6:04

Data recovery support tools


In order to share our knowledge and experience, we decided to create this blog, so we can further explain our products and methods. Our plan is to make this blog as a place for writing about our solutions, ideas and vision.

In this introduction article we will explain the story behind HddSurgery tools and our experience so far. We are hoping that our readers will like this way of presentation and we are expecting to get feedback and suggestions on this and forthcoming articles.


HddSurgery tools

Hard disk drives are compact electro-mechanical devices, which means that movement of their mechanical parts (heads and motor) is electronically controlled.

These HDD moving parts are very prone to different types of malfunctions. These failures are typical consequences of physical impacts on HDDs, especially during its work.


Failures of hard drive heads for example demand replacement of damaged head assembly with functional one. Although definition of head replacement process sounds simple, operation can be covered only to experienced DR technicians, since the smallest error in the process can lead to permanent data loss.

During the process, DR technician needs to take care that heads (or anything else) don't come in any kind of contact with HDD platters and also to prevent mutual contact between the read/write heads. In the time before HddSurgery tools, these contacts were prevented with pieces of paper, cardboard, rubber, foil and similar materials.

Lot of steps in the process in combination with the use of unreliable (soft and easy) materials consequently led to mistakes and chances of their appearance was always high.

These non-standard head replacement procedures in data recovery practice were thorn in the flash for HelpDisc Data Recovery Service technicians. Their ideas in combination with knowledge and experience of mechanical engineers from Erozimat company, led to development and production of the first head replacement tool for Maxtor hard drives DiamondMax9 and DiamondMax10.

This tool enabled head replacement without any contact between tool or heads with the platters and prevented mutual contact between the heads themselves. Tool was followed with detailed user manual in which all steps in the process were described in detail which standardized the process. Video and animation guides followed.

Joint opinion of data recovery community was positive - head replacement process became easier, less prone to mistakes caused by human factor and as such - less stressful.

Positive response from colleagues and friends led to creation of HddSurgery - at first as a tool brand and later as an independent company. In the years that followed, tools were developed for many different types of hard drives and their mechanics.

Hard drive technology developed, many things changed over the years from head parking spot through heads connection with hard drive casing to the appearance of helium filled HDDs. Each change brings new issue to DR professionals and new challenge to the HddSurgery engineers.

Žarko Damjanović - Development Engineer
Miloš Gizdovski - Marketing manager

Re: HddSurgery BLOG

March 31st, 2015, 6:13

HDD Spindle Motor

Hard disk drive is a compact mechatronic component and there is no lot available space for placing its motor. On the other hand, the motors of the hard disks (called "spindle motors") must be able to generate enough torque so the magnetic platters could rotate at the desired speed. This means that the crucial requirement for spindle motors is the large ratio between their power and size.

Hard drive motors are designed for operation at high speeds over a long period of time. This principle is, as such, problematic in the start and can easily lead to defect. Some time ago, in hard drive industry, leading trend was continuous increase of motor speed, so some devices were working on speed over 15,000 RPM.

Speed control, i.e. precise achieving and maintaining the desired RPM, is very important to perform for realizing the basic functions of the hard disk drives - reading and writing data. With the increasing capacity of hard drives, i.e. increasing density of data written on the platters, the speed control becomes more and more difficult task.

Additional conditions set in front of spindle motors are low noise, low cost, low power consumption and less heating during operation. All the above mentioned conditions were satisfied by using brushless DC electric motors. These motors have a rotor with permanent magnet, while current is passed through the stator windings, which leads to a rotation of the rotor.

Inverter, which replaced the classic commutator, is controlled by the current which passes through the stator coils. Rotor position sensor controls the operation of the inverter itself.

Photo: Spindle motor configuration (DiamondMax 10): Stator core, platter carrier, rotor axle, platter tier

Rotating parts of the spindle motors are rotor (spindle) and platter carrier (hat) with a permanent magnet on itself. Stator core is rigidly tied to the hard drive casing. Before, ball bearings were used, while now, almost exclusively fluid bearings secure rotation of HDD spindle motors. The platter carrier, along with the platter tier is rigidly attached to the rotor shaft. In this way, hard drive platter(s) rotates together with the spindle rotor.

Оn older hard drive models, main spindle motor load was emerging in the moment of start, because of stiction between read/write heads and surface of landing zones on the platters. Implementing ramp parking system solved this issue completely. Nowadays, main spindle motor load is coming from windage friction, which is result of high rotational speed of platters.

Engineering teams of leading hard drive manufacturers are actively working on solving this issue. The most frequently mentioned solution is development of hard drives with sealed casing filled with helium. Idea is that if platters would rotate in controlled area with less windage friction, spindle motor load would be significantly reduced, which can lead to larger RPM and better performances of hard disk drives.

Žarko Damjanović, development engineer

Re: HddSurgery BLOG

March 31st, 2015, 8:58

Interview with Dimitris Loulis from Northwind


1. Today we are speaking with Dimitris Loulis, data recovery specialist from Northwind Data recovery. Dimitris, can you tell us about your company?

Hello :) We are one of the largest Data Recovery companies in Greece, located in Thessaloniki. We are currently setting up our expansion offices in Athens too.
We are the only Data Recovery company in Greece who are certified WD partners and also we are the only ones with a full sized Clean Room. The Clean Room is essential for opening Hard Drives in a clean environment, free of dust particles.

2. How did you start with data recovery business?

This is funny. I used to work as a freelance web designer back in 1994. I was considered the 'guru' of computers amongst friends etc and one day one of them called me and he was in panic, because he couldn't access his university diplomatic research.
I recovered the drive, I remember it was a Quantum maybe 2GB in capacity or so, very expensive back then. And then I said, hey, I'm good at this :)

3.The capacity of hard drives is growing each year. What is the biggest challenge in data recovery for hard drives?

The capacity is growing and the technology is getting more complex. I think the bet that needs to be won for Data Recovery is to follow the technology that evolves every day in this business.
We must study hard, research and develop new methods and new ways to get the ultimate goal, to recover the data. And that needs to be done every single day.

4. When was the first time you heard about HddSurgery company?

I do not remember when, but I have a colleague from UK talk to me about how good the quality is and I decided to give it a try. I always invest in good quality equipment which will give us the best result possible.
I do not like average solutions or tools that -might- work. I ordered the first set of tools, gave them a try and since then we have bought all tools and work with them every day.


5. Do you remember your first experience with HddSurgery tools?

Yes. I was working on a WD Sabre drive, 250GB. These are very difficult drives to recover. They don't like it when they have their heads changed. I tried the HddSurgery tool.
After I was finished, I kept wondering how on earth did I work without this tool in the past.

6. By your opinion, what are the advantages of using HddSurgery tools?

They are very well made. The material is nice and well designed. Each tool has a good variety of drives on which you can use it. Even if they are more expensive than the others, the quality always pays back and in the end you get revenue faster because you have more successful recoveries.
Of course, the manuals are awesome and the support is fantastic. Kudos for the animation videos, they are extremely helpful and very impressive.

All in all, I can't imagine myself working without these tools, I use them literally every day and they make some complex tasks very easy. Of course, you have to be very careful at all times.

7. Would you recommend HddSurgery tools to newbies in data recovery business?

Firstly, I would recommend newbies to practice a lot on non-important drives and not to mess with client's data. We see every day drives being tortured by people who call them selves “Data Recovery Professionals” and most of the times it is extremely difficult to recover these drives when desperate clients come to us as a last resort.
I have practiced on more than 700 drives before I started working on live cases.

After that being said, yes, I would definitely recommend HddSurgery tools to everyone. Newbies and experienced professionals. Simply put, they make life easier.

8. How you see the future of data recovery business? What future holds for Northwind Data recovery?

I can't foresee the future of Data Recovery, but I see that the need for more data storage gets bigger every day. At home, I have a storage space of around 8TB which holds music, pictures and movies.
Ten years ago, that would sound like a SciFi movie. But this is reality now and the future holds even more and more storage needs. As for Northwind 's future, as I said we are currently expanding our business in Athens and then in Crete.
We keep on investing in new tools and equipment, we have built the Clean Room and future plans involve a dedicated R&D section.

9. To conclude, what is your message for HddSurgery? Do you have some advice for us?

Yes. Keep producing tools that make the difference. Any serious Data Recovery lab knows that HddSurgery tools are the best on the market - hands down! Keep making innovations and all serious Data Recovery engineers will be loyal to you.

I will NEVER work without your tools anymore and I think that sums it up.

Northwind Data Recovery is a Data Recovery company from Thessaloniki, Greece, that recovers data from hard disks (internal, external, SSD etc), USB Sticks, RAID arrays, flash cards and all storage devices.

Re: HddSurgery BLOG

April 1st, 2015, 4:33

Line up for them autographs, people :P

Re: HddSurgery BLOG

April 1st, 2015, 6:06

hehe.. But it is nice to see who it is we are talking to anyway! Congrats on the successful business you have over there!

Re: HddSurgery BLOG

April 2nd, 2015, 6:26

Thanks HaQue . The guys at HddSurgery have helped us a lot in our success rate. :good:

Re: HddSurgery BLOG

April 14th, 2015, 8:38

HDD motor bearings

At the very beginning of the hard disk drives development, for the purpose of securing safe, fast, smooth and precise rotation of the HDD motor spindle (rotor) - roller ball bearings were used. They secured satisfactory low friction and high reliability at the time and were logical solution in terms of price, productivity and availability.

Gradually, there was more and more need for higher RPM. Increased friction in the bearing and thermal expansion of steel balls due to high working temperatures were the result. The problem of bearing overheating was temporarily solved with usage of the rolling elements made of ceramic material such as silicon nitride and zirconium dioxide. These materials have low coefficient of thermal expansion.

Photo 1: HDD Motor configuration with ball bearings (left) and fluid bearing (right)

Unfortunately, introduction of fluid bearings haven't completely eliminated all possibilities for the motor failures during HDD operation. Currently, the biggest problem in this area is jammed spindle into bearing housing. This defect occurs mostly due to shocks or falls of HDD during operation. Hard drives from the Seagate 7200.11 and 7200.10 families are especially prone to this type of malfunction.

Photo 2: HDDS Spindle replacement tool

HddSurgery, as a company which develops tools and "know-how" solutions in data recovery, worked on a solving HDD spindle motor problem for almost two years.

Original idea was a platter swap. However, since platters are the only irreplaceable HDD part in terms of data recovery, as well as some other technical difficulties on which we encountered during platter swap tool design, we were forced to find another way to solve this DR problem.

Solution was presented to our DR colleagues in 2011. Our HDDS Spindle Replacement Tool Seagate 7200.10/.11 (http://hddsurgery.com/tool/hdds-spindle-replacement-tool-seagate-7200-10-11) was entirely new approach to stuck spindle malfunction.

By using it, jammed fluid bearing assembly (consisting of spindle and bearing housing) is ejected from the patient hard drive and it is replaced with completely functional donor fluid bearing.

It is important to point out that, during the whole process of bearing replacement, any movement of the HDD patient platters in relation to the drive housing is prevented. This means that the functional bearing is mounted on the identical spot where the jammed one was.

Photo 3: HDD jammed bearings

Thanks to this, turnout of the HDD platters is on the same level like on the drives which just came out of the factory. It should be noted that our tool is, from many aspects, safer&better solution than the other approaches - platter swap e.g.

Žarko Damjanović
Development engineer at HddSurgery

Re: HddSurgery BLOG

April 27th, 2015, 7:24

HDD head assembly

Hard drive heads are the most sensitive part of the device. They are responsible for all virtues of modern HDDs, such as read/write speed. However, issues with their functionality represent one of the most common HDD failures.

HDD heads movement is electronically controlled. Their ultra-precise positioning over platters, which rotate with (usually) 5400 or 7200 RPM, is not a simple task from the mechanical point of view. Therefore, HDD head assembly and its functionality is considered as a classic example of successful integration of mechanical engineering solutions with electronics and control.

Photo 1: HDD head assembly

Head assembly consist of two separate subassemblies: head stack assembly (HSA) and head gimbal assembly (HGA). These subassemblies are usually produced in different processes, even different factories. They are assembled into functional unit - head assembly, afterwards.

Parts of head stack assembly (HSA) are: actuator arm (which rotates around fixed axle), its bearing assembly, voice coil and its electronics.

Actuator arm (or access arm) are usually made of aluminium alloys, or less often stainless stell or titanium alloys are used. Aluminium alloys are suitable because of their paramagnetic property and their excellent physical characteristics, primarily strength and low specific gravity. Therefore, actuator arm represents robust but easily movable entity.

Head gimbal assembly (HGA) is connected to the actuator arm front end. It consists of thin (≈0.1mm) pieces of sheet metal on which "sliders" are soldered. These sliders, are the most important part of entire head assembly, as they are responsible for performing read/write operations.

Mass of HGA is negligible, so it can hover on "air bearing" above/bellow platters during read/write operations. "Air bearing" is a thin layer of air, which is formed as a consequence of high RPM of the platters.

Height, on which HGA of modern hard drives hovers above/bellow platters, is, depending on exact model ≈ 70nm. It's important to point out that there is constant tendency in HDD development, to additionally decrease this dimension. If high RPM is taken into consideration, it's clear from where danger lurks...

Sliders are low-volume cubes/cuboids, made of ferrite, by which electric signal is transformed into magnetic recording -writing data or vice versa, by which magnetic recording is transformed into electric signal - reading data. Slider surface is aerodynamically designed so "air bearing" features can be used in the best way. Shape of these surface is known as a "pattern" and it differs from model to model.

Photo 2: HDD head slider - good (left) and bad (right)

Common misbelief about HDD functioning is a theory that it is entirely digital device which operates only with binary code. However, the truth is that magnetic recording on the platters is not a digital signal. Head assembly electronics consist of amplifier and A-D converter. Only after analog signal goes through these units, we can speak about digital device and digital signal.

Photo 3: Analogue signal of good (left) and bad (right) heads

In one of the next blogs, we will write about head assembly actuator and principles of head movement and positioning control.

Žarko Damjanović
Development engineer

Re: HddSurgery BLOG

April 27th, 2015, 21:38

zarko_hddsurgery wrote:Head assembly electronics consist of amplifier and A-D converter. Only after analog signal goes through these units, we can speak about digital device and digital signal.

AISI, the read signal at the HDA connector is analogue whereas the write signal is digital. There really is no A-D or D-A converter electronics within the head assembly, even for the write signal, at least not in the true sense of the word.

Re: HddSurgery BLOG

April 27th, 2015, 23:12

how can you send a digital magnetic signal?

Re: HddSurgery BLOG

April 27th, 2015, 23:29

HaQue wrote:how can you send a digital magnetic signal?

1 = solenoid on
0 = solenoid off

Preamp Block Diagrams:

Read Channel IC example (Philips P32P4911A):
http://pdf.datasheetarchive.com/indexer ... 370646.pdf

The following circuits are ancient, but they give an insight into the digital-to-analogue conversion process.

Circuit diagrams for IBM's original PC/AT MFM HDD and FDD controller:

IBM AT 20MB HDD circuit diagrams:

Re: HddSurgery BLOG

May 6th, 2015, 6:47

HDD actuator

HDD actuator is a device which moves head arm assembly. Its task is, not only to start and secure continuous movement of hard drive head assembly, but also to fully control it. Securing and control of this movement is of crucial importance for performing elementary function of hard drives.

Surface area of HDD platters is divided into large (and increasing) number of sectors for data storage. Actuator brings head arm and its sliders to the right spot over HDD platters, from where data should be read/or where new data should be written. At the same time, electronic controller manage HDD motor operation. Platters are set in position so that firstly actuator, and then sliders, are able to perform their task.

If you consider platters RPM (up to 15000, usually 5400/7200) and the number of sectors which is "packed" on the platters of modern hard drives, it's clear how complex is task of HDD actuators in locating exact sector almost instantaneously.

Servomechanism (left) and Stepper motor (right)

Previously, role of the HDD actuator was performed by stepper motor - electric motors which converts digital electric impulses into predefined angular displacement. This principle of head arm positioning was good enough in the times when density of sectors on HDD platters was significantly lower.

Constant demands for HDD capacity increase (and thus higher density of sectors on the platters) reduced usability of stepper motors, as they became unable to accurately position head arm sliders. In addition, stepper motors are known for their overheating issue - which led to thermal expansions of platters and increased possibility of contact between heads and platters surfaces - aka head crash.

In today's era, stepper motors are no longer used as HDD actuators. They are replaced by so called - servomechanism. Head arm movement is secured and controlled by changing amplitude and polarity of current through the voice coil in the field of permanent magnet.

Voice coil is integral part of head assembly and it is located on its backside. Thus, its movement in the field between two permanent magnets brings entire head assembly into motion.

Magnetic field is secured by using pair of very strong neodymium magnets. These magnets are strong enough to attract a mass which is up to 1000 times greater than their own. Direction of this magnetic force inside hard drives is strictly vertical, otherwise it could cause damage to the data on the platters.

Žarko Damjanović
Development engineer

Re: HddSurgery BLOG

June 16th, 2015, 9:20

HddSurgery data recovery tools training

Last week, HddSurgery held its first official training regarding the usage of HddSurgery data recovery & computer forensics tools.
Multiple presentations about principles of hard disk drive mechanics were also a part of the training.



Re: HddSurgery BLOG

August 24th, 2015, 6:54

Interview with Mike Montgomery from MjM Data Recovery Ltd

1. Hello Mike, please tell us about yourself and your role in MJM Data recovery.
Hi, I am Mike Montgomery, Managing Director of MjM Data Recovery Ltd in the UK.
We set up the company in 1999 and before that was named MjM Computer Publishing where we did a whole range of computer services,
including Data recovery from the late 1980's as a part time business mainly doing back up and computer repairs and installations.


2. What is your history with data recovery?
Started recovering data using Norton disk doctor from floppies in the 1980's as part of the serviced we provided as MjM Computer Publishing,
we went online in 1992 and by 1999 data recovery had become the biggest income source. So we set up MjM Data Recovery and built up a
specialist DR business based on previous knowledge of file systems and developed that with learning about hard disk hardware, electronics and
other storage device mechanics.

Read the rest on http://www.hddsurgery.com/blog/show/art ... montgomery

Re: HddSurgery BLOG

September 28th, 2015, 10:30

HddSurgery training in Bangkok (Thailand)

After another successful HddSurgery tools training, many companies have shown interest in the presentation of the use of HddSurgery data recovery and computer forensics tools.
The next country HddSurgery training was held in was Thailand.

It was hosted by the government's Electronic Transactions Development Agency (Public Organization) or ETDA, Ministry of Information and Communication Technology.
The training took two days to complete.


Read the rest on http://www.hddsurgery.com/blog/show/art ... ng-bangkok

Re: HddSurgery BLOG

November 20th, 2015, 11:11

Interview with Adrian Merdariu from Serman Recuperación de Datos

1. Hello Adrian, can you tell us something about ''Serman Recuperación de Datos''?

Serman was the first laboratory in Spain and one of the first in Europe starting in this field in 1989. Currently we remain a market reference,
we have experienced an exponential increase in the volume of recoveries while downhill in prices.

We bet the steady increase in quality and not only focused on the recovery process but in communication with the client.


2. What is your opinion on the future of data recovery, what kind of challenges are ahead us?

I believe that the future will be an exciting one, probably the challenges will be more in software development than hardware mechanics.

No doubt about it, the development of hardware tools shouldn't be on a second plan.

Read the rest on http://www.hddsurgery.com/blog/show/art ... n-merdariu

Re: HddSurgery BLOG

June 23rd, 2016, 9:13

Opening the hard drive – Regular vs. Clean room environment

Data recovery sometimes does not require the patient drive to be opened, but when it does, a specific problem occurs - exposure of the hard drive’s interior to the influence of the environment in which the data recovery operations are performed.


Compared to the hard drive’s interior, the surrounding environment’s air is filled with particles of different sizes, and if those particles get in contact with the surface of the hard drive platters, they can irreversibly damage the delicate magnetic coating, creating bad sectors and thus permanently erasing the data recorded in those sectors.

Read the rest on http://hddsurgery.com/blog/opening-the- ... nvironment

Re: HddSurgery BLOG

August 19th, 2016, 7:26

HDDS WD Black 2.5''-3.5'' Ramp set updated model list

Since the publishing, HDDS WD Black 2.5''-3.5'' Ramp set has been a great success.

Recently, we have been receiving a lot of inquiries about the new Western Digital 6TB hard drives,
which lead our R&D team into a research of the mechanics of these drives....


Read the rest on http://hddsurgery.com/blog/wd-black-updated-model-list-

Re: HddSurgery BLOG

November 28th, 2016, 10:52

Grand opening of Ace Lab new office in Prague

This November we have been honored by the invitation from Ace Lab company to attend the opening of their new offices in Prague, Czech Republic.

November is not the most beautiful month to visit Prague, but although it was cold outside, our kind hosts tried their best to make us feel comfortable as their guests....


Read the rest on HddSurgery blog page.

Re: HddSurgery BLOG

February 23rd, 2018, 11:04

A successful training for the Head replacement tools

Recently we held one more training for the usage of our Head Replacement Tools.

The training was successfully demonstrated in our office where we presented various types of Seagate, Western Digital, Samsung and HGST drives.


Read the rest on HddSurgery blog page.
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