What’s my RTO? Determining Downtime Tolerance
January 27, 2015
scored hard drive
Data Recovery 101: Burnishing Platters
January 30, 2015

Introduction: Data Recovery 101

Gillware is rolling out a new blog series titled “Data Recovery 101”, in which our bloggers will take a closer look at each of the different components of a hard drive and explain how they work, how they fail and how we recover the data from each failure situation.

The series will include five of the main components of a hard drive: platters, read/write heads, spindle motor, firmware and electronic components such as the control board and other circuitry. When a hard drive is functioning properly, these parts work together in an intricate balance. The parts are very delicate, and even the slightest malfunction can have disastrous consequences.

We see a variety of different failures on a daily basis, both logical and mechanical, and most failures can be tied back to one of the five components mentioned above. In the blog series, we’ll analyze each failure to give you a better idea of what’s going on inside a failed drive. But we won’t stop there, of course. We’ll also give you an inside look at some of the advanced techniques Gillware uses to recover data from different failure situations. This post will focus on the part of the drive that stores the data itself: the platters.

What are the platters?

Platters are the thin, circular discs made of glass or aluminumhdd_photo150 inside the sealed hard drive enclosure. Depending on the capacity and age of the device, a hard drive can contain anywhere from one to 10 or more platters. Each platter surface is coated with an extremely thin magnetic substrate that stores the user’s binary data (1s and 0s) in the form of a magnetic field. When these 1s and 0s are arranged in a particular order, the device can read recognizable data like pictures, documents, spreadsheets and more.

How do the platters work?

Read/write headstack

In order to store information, the binary data must be written to the magnetic surface of the platter. To access the data, it must be read. Another crucial hard drive component, the read/write head assembly, is responsible for both of these functions. The read/write heads are tiny sensors that float just 5-10nm above the surface of the platters on a cushion of air generated by the platters spinning at thousands of rotations per minute.

When operating normally, the airflow inside the hard drive chassis is smooth and consistent, resulting in the steady flight of the read/write heads over the platter surface. Although hard drives are not technically hermetically sealed devices (except for some of the new, ultra high density HDDs being built), the internal environment does need to remain free of dust and other contaminants to ensure that the heads can float unobstructed over the platters.

How do the platters fail?

In certain situations, the read/write heads can crash and contact the delicate platter surface. Since the heads are so close to the platters, even a tiny speck of dust, dirt or a fingerprint can have adverse effects on the operation of the drive (which is why it’s so important not to open hard drives outside of a cleanroom environment).

Severely scored hard driveThe heads can crash for a variety of reasons including spindle motor failure, power surge or sudden loss of power, among others. While this can be an entirely separate issue, the real problem can be damage to the magnetic substrate caused when the heads contact the platters and spread microscopic debris throughout the chassis which can become embedded in the platter surface. In serious cases, rotational scoring occurs, leaving score marks in the magnetic substrate when the read/write heads touch the surface as the platters rotate.

Though the damage may be microscopic, the debris continually impacts the read/write heads and eventually destroys them, making the drive inoperable and the data inaccessible. Even if the heads are replaced, the damage to the platters must be addressed, or any replacement heads will just get destroyed as well.

How can you recover data from damaged platters?

hdd_glass_platterSometimes, if the damage to the platters is too severe, the data stored on them can be unrecoverable. For example, some of the more extreme cases we’ve seen in our data recovery lab involve shattered platters, melted platters, or platters that have had the magnetic substrate completely removed from them from such a high degree of rotational scoring. When the platters are broken, incinerated or stripped of their coating, there is simply nothing to recover the data from.

laptop burnishIn situations where the magnetic substrate is largely intact, Gillware utilizes sophisticated equipment used by hard drive manufacturers, re-engineered for the purposes of data recovery, to measure and eliminate platter debris and imperfections.  The process is known as burnishing. In order to undergo burnishing, the platters are removed from the hard drive chassis in a controlled, cleanroom environment. The platter is mounted on a custom fixture that spins the platter in excess of 10,000 RPM, which is nearly twice as fast as the platters rotate in an average hard drive. A robotic arm passes a specially designed burnishing head over the platter, which works as a precise scrub brush to remove debris and repair damage on the platter surface. Then the platters are remounted, the new heads are installed and the drive is calibrated.

Although it will not be in perfect working order, the drive is now operational to a point at which the data can be successfully extracted from the device and recovered.

To learn more…

In the posts to come, you’ll learn more about the different hard drive components we discussed in this post (read/write heads, spindle motor and more) and how they work together to create a fully functioning hard drive. Additionally, we’ll show you what can go wrong with each of these components and how Gillware recovers data from different situations of hard drive failure.

If you’re interested in learning more about how the burnishing process works, check out our burnisher blog post.

37 Comments

  1. […] a century, the data is still stored in a magnetic format on circular disks commonly referred to as platters. From a recovery standpoint, as long as the platters are healthy, the data can likely be […]

  2. […] discs coated in a fine magnetic substrate. This magnetic storage media, commonly referred to as the platters, is subdivided into tracks, cylinders and blocks. For simplicity, blocks are typically referred to […]

  3. […] sensors (about 0.1 – 0.3mm tiny) that do just what their name implies: read data stored on the platters and write data to the platter surface. Although some hard drive configurations involve just a single […]

  4. […] discs coated in a fine magnetic substrate. This magnetic storage media, commonly referred to as the platters, is subdivided into tracks, cylinders and blocks. For simplicity, blocks are typically referred to […]

  5. […] USB thumb drive or camera card is an industry-standard NAND flash memory chip. Whereas hard disk platters can realistically only be read by the drive that recorded to them, that memory chip can be removed […]

  6. […] it reads data, it floats within a few nanometers of a spinning platter. Tiny magnetic differences on the surface of the platter — basically on or off signals […]

  7. […] USB thumb drive or camera card is an industry-standard NAND flash memory chip. Whereas hard disk platters can realistically only be read by the drive that recorded to them, that memory chip can be removed […]

  8. […] system for your phone, a complicated device needing to store and organize billions of bits onto platters or NAND needs an operating system. I personally prefer the term hard drive operating system or HDD […]

  9. […] film that are either magnetized or not. They are arranged in concentric circles on all sides of the multiple spinning discs inside a hard drive.  Eight of these 1s or 0s is called a byte, and a byte has 256 possibilities, […]

  10. […] attempt in the lab. Aside from the obvious barriers, like the chance of dirt or dust touching the platters, cover removal poses other threats to a successful recovery as […]

  11. […] million bad sectors, which meant portions of the drive were unreadable. A hard drive stores data on platters coated in fine magnetic substrate. Platters are divided into tracks, cylinders and blocks. Blocks […]

  12. […] sensors (about 0.1 – 0.3mm tiny) that do just what their name implies: read data stored on the platters and write data to the platter surface. Although some hard drive configurations involve just a single […]

  13. […] a century, the data is still stored in a magnetic format on circular disks commonly referred to as platters. From a recovery standpoint, as long as the platters are healthy, the data can likely be […]

  14. […] hammer” BUSTED Inside a hard drive are thin, circular discs made of glass or aluminum called platters, along with tiny metal arms called the read/write head assembly. Platters are covered in a thin […]

  15. […] hammer” BUSTED Inside a hard drive are thin, circular discs made of glass or aluminum called platters, along with tiny metal arms called the read/write head assembly. Platters are covered in a thin […]

  16. […] run power to a hard drive, a spindle motor inside it begins to move This motor spins the drive’s platters containing your data at 5,400 to 7,200 revolutions per minute. The movement of the hard disk […]

  17. […] latop-sized hard drive platters are frequently made out of glass and coated with magnetic substrate. The substrate provides not […]

  18. […] hard drives store data on both sides of multiple hard disk platters. Each platter surface with data on it has a single read/write head assigned to it. When our […]

  19. […] of your data lives on the shiny, pristine surfaces of the hard disk platters inside your drive. These platters are made out of either aluminum or glass; the thin layers of […]

  20. […] your hard drive, a spindle motor spins the hard disk platters inside at several thousand revolutions per minute. To read and write data to these disks, delicate […]

  21. […] that the drive’s read/write heads had crashed. There was some moderate damage to the drive’s platters as well. The drive needed its read/write heads […]

  22. […] The drive’s read/write heads had failed and were repeatedly making brief contact with the data storage platters, producing “dings” on the platter surfaces. When the heads were pulled away from the […]

  23. […] the drive up in our cleanroom showed that the read/write heads were mangled and the sensitive hard disk platters had sustained some minor […]

  24. […] of the data on your hard drive lives on the surfaces of the hard disk platters within the drive. Most hard drives have multiple platters, writing data to both sides of each. When […]

  25. […] your hard drive clicks once upon startup when the heads leave their ramps and fly over the platters. When the heads can’t read anything, they leave their ramps, fly over the platters, and come […]

  26. […] mangled the hard drive’s delicate magnetic read/write heads or visibly damaged the drive’s platters. But the read/write heads weren’t in optimal condition, and this had caused a certain other part […]

  27. […] data properly work just as hard as the mechanical system of read/write heads, spindle motor, and hard disk platters. For Mike Garland, a professional drag race photographer from Fulton, IL, a failure of these […]

  28. […] a hard drive that will corrode if they get wet and then are exposed to air for too long. Hard drive platters in particular are especially vulnerable to corrosion. If floodwater manages to seep into the drive, […]

  29. […] allows these arms to move up and down, carrying the heads just above the radius of the spinning disk platters. You will almost always find several heads in a modern hard drive, stacked together to form a head […]

  30. […] drives store their firmware on the same hard disk platters they store the rest of their data on. One of hard drive firmware’s many tasks is to keep track of […]

  31. […] system for your phone, a complicated device needing to store and organize billions of bits onto platters or NAND needs an operating system. I personally prefer the term hard drive operating system or HDD […]

  32. […] USB thumb drive or camera card is an industry-standard NAND flash memory chip. Whereas hard disk platters can realistically only be read by the drive that recorded to them, that memory chip can be removed […]

  33. […] the read/write heads can collide with it. This would kill the heads and scrape off some of the magnetic coating that contained the hard drive’s data. Cleaning off the platters to prevent any further damage and […]

  34. […] a century, the data is still stored in a magnetic format on circular disks commonly referred to as platters. From a recovery standpoint, as long as the platters are healthy, the data can likely be […]

  35. […] of the three hard drives revealed that the corrosive substance hadn’t caused much damage to the data storage platters. This was a relief for all of us here at Gillware. However, the drives’ read/write heads hadn’t […]

  36. […] film that are either magnetized or not. They are arranged in concentric circles on all sides of the multiple spinning discs inside a hard drive.  Eight of these 1s or 0s is called a byte, and a byte has 256 possibilities, […]

  37. […] a hard drive are thin, circular discs made of glass or aluminum called platters, along with tiny metal arms called the read/write head assembly. Platters are covered in a thin […]

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