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Latest data recovery news. R&D and other news

  • What is a head crash ?

    by: MJM Data Recovery Limited

    What is a head crash ?

    A head crash is where the read write heads come into contact with the hard drive's platters resulting with damage that causes the drive not to function correctly.


    In order to understand what a head crash is, we need to know how the heads write and read data to the platters. The Heads, or Read-Write heads as they are correctly known, read and write data to the platters as magnetic flux patterns on the surface of the platters.

    Modern hard drives use magnetic recording technology, which means that the magnetic surface of the platter has a magnetic pattern written to it according to the data you want to store there. As the head moves over the area where it is to be written, a small voltage is passed through the head, according to the voltage it will affect the magnetic surface directly underneat the head. This creats the magnetic flux pattern in the 'recording medium' as shown in the image below.

    Perpendicualr Recording

    When data is written, the magnetic poles flip from say the N pole pointing up to the S Pole pointing up. The arrows in the diagram indicate the direction of the field.

    When you place a coil that is connected to a galvanometer close to a magnet, you will see current flow in one direction or the other depending on the polarity of the magnet.

    In hard drives, the polarity depends upon which pole the read head is near. Either North or South, this then is converted into binary code 0 and 1.

    The physical heads float on a cushion of air a fraction of a micron (<0.001mm) above the platter surface but within the area of the magnetic field. The data is read very quickly and is converted into the word document, photo or vide that you want to load into the computer.

    The Head Crash

    Please note the photos in this article were taken inside a class 100 cleanroom.

    When the read write heads come into contact with the rotating platter of the drive, this is known as a head crash. The results of which can vary depending on the level of impact on the head to platter contact.

    This image shows what a normal hard drive should look like. You can see that the platters have a mirror like look to them, they are much smoother than a mirror and are finely polished to get the right surface finish.

    Clean hard drive

    This photo shows the results of a head crash, in this instance it can be seen that much of the top platter surface has been destroyed.

    In some cases where the damage is not too severe or is restricted to a single platter, it is possible to recover data from the platter areas not damaged, we have techniques for avoiding damaged areas and for physically removing heads where the damage is beyond recovery and reading from the other heads.

    Obviously, there are some limits to what can be recovered using the techniques, but for smaller files like photos and word documents, etc. Some recovered data may be useful. The downside is that this type of recovery can be very expensive as it may involve several sets of heads and long periods of time whilst the cloning process is complete, and unfortunately there is no absolute guarantee of recovery.

    Follow the link for more information about our hard drive recovery services.

     

  • Recovery from a deleted VMDK file Recovery of a VMDK file after it has been deleted or gone missing from A VMWare system is a difficult operation. The VMFS/ESXi is a basic operating system that does not have undelete features built in, hopefully VMWare will build this into later versions of their file systems. At MjM we are able to recover deleted VMWare VMDK files. We will need access to the disk array or LUN…

  • Seagate Slim Head Combs When Roseweed drives with failed heads first started appearing for data recovery, we found out very quickly that safe removal and replacement of the heads was going to be a very difficult procedure. Because there is no room to use a standard head comb, and no tools were commercially available, we spoke with Specialist Engineer Nikola Radovanovic at HDD Surgery in Serbia. His company has been making state-of-the-art head combs for…

  • Chip off Recovery When it comes to chip-off data recovery, it is essential to use the most advanced equipment available to ensure that you have the best chance of recovering data by directly reading the memory device and rebuilding data structures stored on - for example - phone cards, phone memory chips, usb sticks or any other removable memory device. The most common devices used are based on NAND technology. We currently use the three…

  • Trading Standards AnnouncementMjM Data Recovery ltd are proud to have been approved to the Trading Standards 'Buy with Confidence' scheme. After an in depth audit, confirming details with customers and interviews we were accepted to be a company that people can trust.https://www.buywithconfidence.gov.uk/profile/mjm-data-recovery-ltd/17444/

  • Volume set data recovery Whilst a volume set is nothing exceptional to write about, in this instance the job had been to another data recovery company and they pronounced it as unrecoverable. The customer had thought that the failed drive contained a single data partition. However, soon after analysing the file system meta-data, we discovered that the drive was the second drive from a two drive volume set. We phoned the customer, and they confirmed…

  • HP Appliance Data Recovery We have just completed a massive recovery for a large UK corporation. They lost a specialist application server containing over 24 million files, but they knew where to come for help. The system was a RAID 5 that had suffered failures on two of the RAID 5 drives, to make this more complex the file system was further configured in external data blocks which we had to virtually merge together to…

  • Toshiba hybrid hard disk recovery. MjM Data Recovery Ltd are able to recover data from the Toshiba Hybrid laptop hard disk drives.These are mainly platter based hard disks, but with a small SSD built-in to the controller board to help speed up disk read/write operations. When problems occur the symptoms are that the drive will show as normal in the computer BIOS, but the data is inaccessible. Any attempts to read the drive result with…

  • Seagate SSHD Recovery. Data recovery from the slimline Seagate SSHD/Hybrid drives. When these drives fail because of a problem within the SSD firmware, the drive may show one (or more) of the following symptoms. Drive no longer spins. Drive spins but is not recognised Drive spins and is recognised, but data can not be read. These can be issues within the Firmware of the SSD section of the drive. One of the problems data recovery…

  • Seagate drives with locked firmwareSome years ago there was a problem with the Seagate 7200.11 range of drives. The problem was so big that thousands of users ended up with bad drives. Someone developed and made freely available a Firmware (FW) fix that could repair most of the problems with the drive but it needed some hardware (a cheap TTL Adapter) in order to access the FW and they provided the factory codes in order…

  • Hard disk drive fault analysisData recovery from drives that have suffered a physical failure require a structured analysis regime. This involves visual inspection, electronics diagnosis, firmware analysis and testing of the read-write heads.Diagnosis is absolutely the most important stage of the data recovery process because a mis-diagnosis can severely change the outcome of a recovery. Some data recovery companies use an ad-hoc method of trying this and trying that but we believe that is not…

  • Seagate Data RecoveryBack in 2008 Seagate developed the new technology name F3 this started with the Seagate 7200.11 hard disks. Not long after they came out a firmware issue was discovered that rendered the drive 'bricked' the Seagate forums became inundated with complaints about the drives. We are able to recover from all Seagate F3 series of drives including 7200.11, 7200.12 desktop and enterprise (ES) versions.We are able to access and repair the firmware on…

  • The Functions of ATA Registers in a Hard Disk Drive A hard disk contains a set of registers or ports that are used to communicate to and from the computer. For the end user these ports are normally not significant but when it comes to hard disk firmware programming and direct drive access, knowledge of these ports and how to use them programmatically is very important. Firstly there are two main modes of port access.…

  • Intel SSD with BAD_CTX and showing as 8MB   This problem has been around for a few years now and when it first appeared it caused quite an uproar in the Intel SSD forums. Intel found a solution to the problem, updated the firmware and provided a download for users. There was only one problem, the firmware upgrade results with a complete overwrite of the drive wiping all traces of data.   The problem is…

  • Fake Memory Cards. They come in many forms and it is very difficult to tell a real one from a fake, for almost any memory card you can buy there are fakes. We have seen fakes of all sizes and none of them have anything like the capacity that they are advertised as. Some sellers that sell them put disclaimers in their descriptions that the memory sticks may not be of the expected capacity and…

  • ReFS Data Recovery With Microsoft Server 2012, Windows 8.1 and Windows 10 the MS Resilient File System or ReFS arrived. The Resilient File System (ReFS) is a new type of self repairing file system. It is designed to improve data availability, even when errors that would previously have caused data loss. Even this type of system can fail due to hardware errors, or through other problems such as user error or virus attack. We are…

  • SSD Data Recovery MjM Data Recovery Ltd make a breakthrough in SSD recovery techniques.  Our research and development engineers have found ways to resolve the 'Busy' problem that affect many makes of drive. The symptoms are that the drive is not recognised by the computer and for those in the Data Recovery trade, the drive status registers show a BSY state.   Our engineers have found a way to repair these drive regaining access to…

  • Toshiba Data RecoveryData recovery from all Toshiba hard disks. From noisy-clicking drives to those that are not spinning at all. From drives where the data has gone missing or is visible but not accessible. MjM Data Recovery have new technology that helps to read Toshiba drives that suffer with the following problems. Drive slow to initialise or just hangs the computer Thousands/Millions of bad sectors reported. Some data recovery companies have tried changing heads, controller…

  • Bad sector remapping When a hard disk is manufactured, there are areas on the platter that will have bad sectors. Considering that on a 3 TB hard disk there are 6 billion sectors, then a few thousand bad sectors is only a small proportion of the total number of sectors on the drive. During the test phases of a hard disk at the factory, the platters are scanned and all the bad sectors are mapped…

  • Slow Responding WD DrivesThis problem first appeared mid 2011 and we started seeing a number of drives that were slow to initialise and again when attempts were made to read data the drive would either be incredibly slow or would hang the computer, on computers where affected drives were the main drive, the computer would not even start. Many people and other DR companies were misinterpreting this problem as weak heads or failed media. We…