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In computing there have been, and will continue to be, an abundance of ways to record data. Today, the three that are used, and that we work with here at Carolina Data Recovery, are magnetic, optical, and digital (semiconductor) memory, and these are often in the form of optical disk drives (ODDs), hard disk drives (HDDs), or solid-state drives (SSDs). We’ll compare these three types of data recording, looking at how they differ and how they are the same.

The optical disk drive (ODD) is a methodology of data reading and writing that was once common, but has fallen out of computing fashion with the advent of better methods. This process, know as optical recording, consists of a laser light that reads and writes off of an optical surface, like a disk. This is the functionality of older desktops with floppy drives and even more recently with videogame consoles and Blu-Ray players. For a more technical understanding, here’s how it works: 

  • There are two main components to an optical disk drive: a pickup head and two servomechanisms.
  • The pickup head (PUH) has a semiconductor laser, a focusing lens, and photodiodes that detect light from the disk’s surface.
  • The two servomechanisms each have their own function. The first is to ensure correct distance between the lens and the disk, ensuring the laser is in a small, precise spot. Second, beginning at the outer-most edge, the PUH is moved along the disc’s radius, keeping the laser on track in a continuous spiral.
  • Traditionally, and unlike hard disk drives as will be discussed below, ODDs used constant linear velocity (CLV) to achieve a constant streaming bit rate.
  • Now, because of increases in rotational speed, ODDs use zoned constant linear velocity (Z-CLV). This is when a disc has multiple zones with unique CLVs for each zone.

The hard disk drive (HDD), and its use of magnetic recording, is largely what weakened the presence of ODDs and optical recording in personal data storage. These drives are found everywhere from desktops, laptops, and external drives to DVRs, videogame consoles, and even cars. We have discussed this process before here, but here is another break down on how HDDs work:

  • There are two main components in a hard disk drive: a magnetic read-write head and two magnetic platters.
  • The magnetic-head moves across the platter changing or reading the polarity of the various segments on the platter.
  • The two platters are coated in a ferromagnetic material that allows for the polarity of its surface to be affected.
  • The platter is divided into a grid like series of zones. Each zone has a polarity that denotes it as positive or negative. The magnetic-head moves across the platters and detects the polarity as binary, one of the basest of computer coding language.
  • The HDD, unlike the ODD as discussed above, uses constant angular velocity (CAV) to achieve a constant number of revolutions per minute. This is all happening as the magnetic-head travels to a specific area of the platter to read or write, as need demands.

The solid-state drive (SSD) is a much more recent addition to the memory field, and uses the more advanced method; digital (semiconductor) recording.  These drives are, like HDDs, everywhere from personal computing devices to massive corporate data systems, like RAID. The digital (semiconductor) recording process is quite complex, but there are some essentials that are worth knowing:

  • Data in these systems is stored in semiconductor cells; cells that utilize semiconductors along an integrated circuit, often achieving random access.
  • Random access means that, unlike HDDs, the data stored anywhere in an SSD can be accessed as quickly as memory stored anywhere else. Latency is decreased due to the lack of the magnetic-head.
  • Each drive has a Controller that links the memory mechanics of the drive to the computer’s components.
  • Originally, most SSDs used a volatile memory type called DRAM. It was fast, but it could not hold data without constant power. Now, most SSDs use the non-volatile NAND due to its ability to retain memory without power.
  • Some drives are hybrid-drives that consist of both traditional HDD and more modern SSD working in synchronicity to achieve faster storage and higher capacity.

Now that we have had a chance to discuss the vast and complex differences found in ODDs (optical recording), HDDs (magnetic recording), and SSDs (digital/semiconductor recording), let’s discuss the ways they are the same.

  • They all have complex parts that are incredible pieces of technology.
  • They are all vulnerable to electrical, fall, fire, and flood damage.
  • They can all be looked at by the experts at Carolina Data Recovery, offering data recovery and hard drive repair. 

If you or anyone you know needs quality data recovery or hard drive repair, please come and contact use at Carolina Data Recovery. For over 20 years we have been providing our services, successfully working with optic, magnetic, and digital media stored on hard disk drives (HDDs), solid-state drives (SSDs), and even RAID or NAS Systems.

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