Wednesday, July 7, 2010

Data Recovery Myths - Part I

The “Freeze It’ Myth, The “Heat It” Myth, And The “Firmware” Myth

The freeze it myth is interesting and makes some sense, but the consequences are a disaster!

During the manufacture of a hard disk drive it’s necessary to calibrate the read/write mechanisms so that the heads get correctly positioned over the disk surface at a determined tolerance, in order to allow the heads read and write on the correct tracks without any kind of error.

Some manufactures, in some models and series, record all those parameters in a ROM memory located in the logic board, or a part is recorded in that ROM and another part in an EPROM or some kind of flash memory that’s inside the drive. This explains why many times the simple replacement of a burned logic board for an identical one using the same firmware version doesn’t make the hard drive come back to life: something is wrong on the inside.

There’s also a kind of surface recording that’s made during the manufacturing process, which is called “servo”, that helps the heads to position correctly. Many times that factory magnetic recording is altered by some reason related to the surface material, and the head starts moving back and forth.

Someone suspected it had some relation with temperature effects and decided to freeze the hard drive in the freezer and then run to connect it back to the PC, and bingo! The drive was recognized and worked again... for some minutes. New freezing session and the drive worked for some more minutes, enough to save some megabytes of information. Then the disk stops working for good.

We’ve read in a forum that when we freeze the hard drive, its interior gets “rearranged” and everything goes back where they belong. This information makes some sense, since the retraction of the material due to the low temperature could have helped the read heads find the tracks again, in some cases. But why the drive stops forever?

Because the disk’s magnetic surface was highly degraded and there comes a time when the “freeze/heat” doesn’t work anymore. The result: the few chances of recovering a good part of data have maybe gone to space. Not to talk about the condensation of the air inside the hard disk (yes, the HD has clean air inside it, a filter to prevent impurities, and a dehumidifier sachet). Read our tutorial Anatomy of a Hard Disk Drive to see this.

One more myth “busted”. Regarding the heat it myth, well... I think there’s no need to comment on this, but there are people who commit and support this crime!

Saturday, July 3, 2010

Firmware Updates for Seagate Products

Seagate products are run by firmware. Having the latest firmware can improve performance and or reliability of your product. Seagate recommends applying new firmware to enhance the performance and or reliability of your drive.

Like any software, firmware is improved over time and problems are also fixed. Every drive family has a couple of firmware releases during the life of the product. Please check in regularly to determine if new firmware is available for your drive.

As new firmware becomes available for other products we will make note of it here. At this time, we have firmware available for Barracuda 7200.12, DiamondMax 23, Barracuda LP, Barracuda 7200.11, Barracuda ES.2 (SATA) and DiamondMax 22 drive families.

If newer firmware is available for your drive, it will reflect the improvements we have engineered for the latest manufacturing. Firmware for legacy products will be the final release from manufacturing. Please note that Seagate does not offer details about specific firmware.

Until recently, firmware updates for typical desktop and laptop computers were difficult and somewhat risky. This situation, in part, was based on a lack of friendly firmware download tools and operating system limitations. This situation has improved and Seagate now offers firmware updates as a routine matter for the general support of your Seagate drive.

If you are troubleshooting a system or OS problem, you should not consider firmware updates until after exploring more typical troubleshooting steps like file system error checking and anti-virus scanning.

Please use the following links and instructions below to determine if firmware is available for your product. If firmware is available, we recommend that you make a back up before running the actual update and that you read and follow all instructions, cautions and warnings that may be displayed.
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Friday, July 2, 2010

Download Latest Version of MHDD 4.6

MHDD is the most popular freeware program for low-level HDD diagnostics.
MHDD supports these interfaces: IDE, Serial ATA, SCSI. Also there is a possibility to access an USB storage, there are drivers for emulation (USB->SCSI).
This software can make precise diagnostic of the mechanical part of a drive, view SMART attributes, perform Low-level format, bad sector repair, different tests and tens of other functions.

License: Freeware
Author: Dmitry Postrigan
Operating System: pure MS-DOS (boot-floppy and boot-CD available)

Download the Latest MHDD 4.6 Here and Create your own Bootable CD.

Hard Drive Click of Death Explanation and Live Demonstration

Just found a good demonstration from youtube explaining why you hear clicking noise from a hard drive.

Error Handling of a Hard Drive

Modern drives also make extensive use of Error Correcting Codes (ECCs), particularly Reed–Solomon error correction. These techniques store extra bits for each block of data that are determined by mathematical formulae. The extra bits allow many errors to be fixed. While these extra bits take up space on the hard drive, they allow higher recording densities to be employed, resulting in much larger storage capacity for user data.In 2009, in the newest drives, low-density parity-check codes (LDPC) are supplanting Reed-Solomon. LDPC codes enable performance close to the Shannon Limit and thus allow for the highest storage density available.

Typical hard drives attempt to "remap" the data in a physical sector that is going bad to a spare physical sector—hopefully while the number of errors in that bad sector is still small enough that the ECC can completely recover the data without loss. The S.M.A.R.T. system counts the total number of errors in the entire hard drive fixed by ECC, and the total number of remappings, in an attempt to predict hard drive failure.

Structure of Hard Drive

A hard disk drive (hard disk hard drive,HDD) is a non-volatile storage device for digital data. It features one or more rotating rigid platters on a motor-driven spindle within a metal case. Data is encoded magnetically by read/write heads that float on a cushion of air above the platters, with modern storage capacity measured in gigabytes (GB) and terabytes (TB).

Hard disk manufacturers quote disk capacity in SI-standard powers of 1000, wherein a terabyte is 1000 gigabytes and a gigabyte is 1000 megabytes. With file systems that measure capacity in powers of 1024, available space appears somewhat less than advertised capacity.

The first HDD was invented by IBM in 1956. Advances in capacity, cost, and physical size led them to displace floppy disks in the late 1980s as the preferred secondary storage mechanism for personal computers. Most desktop systems today have standardized on the 3.5" form factor, and though mobile systems most often use 2.5" drives, both sizes operate on similar high-speed serial interfaces.

HDDs record data by magnetizing ferromagnetic material directionally, to represent either a 0 or a 1 binary digit. They read the data back by detecting the magnetization of the material. A typical HDD design consists of a spindle that holds one or more flat circular disks called platters, onto which the data is recorded. The platters are made from a non-magnetic material, usually aluminum alloy or glass, and are coated with a thin layer of magnetic material, typically 10–20 nm in thickness — for reference, standard copy paper is 0.07–0.18 millimetre (70,000–180,000 nm) thick — with an outer layer of carbon for protection. Older disks used iron(III) oxide as the magnetic material, but current disks use a cobalt-based alloy.

A cross section of the magnetic surface in action. In this case the binary data is encoded using frequency modulation.The platters are spun at very high speeds. Information is written to a platter as it rotates past devices called read-and-write heads that operate very close (tens of nanometers in new drives) over the magnetic surface. The read-and-write head is used to detect and modify the magnetization of the material immediately under it. In modern drives there is one head for each magnetic platter surface on the spindle, mounted on a common arm. An actuator arm (or access arm) moves the heads on an arc (roughly radially) across the platters as they spin, allowing each head to access almost the entire surface of the platter as it spins. The arm is moved using a voice coil actuator or in some older designs a stepper motor.

The magnetic surface of each platter is conceptually divided into many small sub-micrometre-sized magnetic regions, each of which is used to encode a single binary unit of information. Initially the regions were oriented horizontally, but beginning about 2005, the orientation was changed to perpendicular. Due to the polycrystalline nature of the magnetic material each of these magnetic regions is composed of a few hundred magnetic grains. Magnetic grains are typically 10 nm in size and each form a single magnetic domain. Each magnetic region in total forms a magnetic dipole which generates a highly localized magnetic field nearby. A write head magnetizes a region by generating a strong local magnetic field. Early HDDs used an electromagnet both to magnetize the region and to then read its magnetic field by using electromagnetic induction. Later versions of inductive heads included metal in Gap (MIG) heads and thin film heads. As data density increased, read heads using magnetoresistance (MR) came into use; the electrical resistance of the head changed according to the strength of the magnetism from the platter. Later development made use of spintronics; in these heads, the magnetoresistive effect was much greater than in earlier types, and was dubbed "giant" magnetoresistance (GMR). In today's heads, the read and write elements are separate, but in close proximity, on the head portion of an actuator arm. The read element is typically magneto-resistive while the write element is typically thin-film inductive.

HD heads are kept from contacting the platter surface by the air that is extremely close to the platter; that air moves at, or close to, the platter speed.[citation needed] The record and playback head are mounted on a block called a slider, and the surface next to the platter is shaped to keep it just barely out of contact. It's a type of air bearing.

In modern drives, the small size of the magnetic regions creates the danger that their magnetic state might be lost because of thermal effects. To counter this, the platters are coated with two parallel magnetic layers, separated by a 3-atom-thick layer of the non-magnetic element ruthenium, and the two layers are magnetized in opposite orientation, thus reinforcing each other. Another technology used to overcome thermal effects to allow greater recording densities is perpendicular recording, first shipped in 2005,[10] and as of 2007 the technology was used in many HDDs.

Grain boundaries are very important to HDD design. The grains are very small and close to each other, so the coupling between adjacent grains is very strong. When one grain is magnetized, the adjacent grains tend to be aligned parallel to it or demagnetized. Then both the stability of the data and signal-to-noise ratio will be sabotaged. A clear grain boundary can weaken the coupling of the grains and subsequently increase the signal-to-noise ratio. In longitudinal recording, the single-domain grains have uniaxial anisotropy with easy axes lying in the film plane. The consequence of this arrangement is that adjacent magnets repel each other. Therefore the magnetostatic energy is so large that it is difficult to increase areal density. Perpendicular recording media, on the other hand, has the easy axis of the grains oriented perpendicular to the disk plane. Adjacent magnets attract to each other and magnetostatic energy is much lower. So, much higher areal density can be achieved in perpendicular recording. Another unique feature in perpendicular recording is that a soft magnetic underlayer is incorporated into the recording disk. This underlayer is used to conduct writing magnetic flux so that the writing is more efficient. This will be discussed in writing process. Therefore, a higher anisotropy medium film, such as L10-FePt and rare-earth magnets, can be used.