CMR and SMR
As of today, many are aware of the immense technological advancement humanity has managed to accomplish. By Moore’s Law, we can expect the speed and capability of our computers to increase every couple of years, and the price we will be paying is inversely proportional to the ensuing technology. As for Hard Drives, we will be looking at two common forms in which your HDD accommodates your data with a remarkable amount to size ratio.
Before we let you into the specific ways a hard drive records data. At the heart of the HDD lies a disk running at high speeds: The Platter, the Read/Write head, Mechanical arm (click here for details) Magnetic data is stores on the Platter, which are typically made using an aluminum, glass or ceramic substrate. Each disk is coated with a film of microscopic magnetized metal grains. Data is recorded in bits, or a magnetic pattern achieved by a group of metal grains. Each region is used to represent a single binary unit of information, which is defined by one of two possible magnetization states – which correspond to zeroes and ones. This data is written by an electromagnet which optimizes the state of each bit in accordance to your data.
Conventional Magnetic Recording (CMR)
CMR is the technology which is used in the traditional HDD we are more familiar with. In essence, when data written onto a CMR drive, the magnetic elements on the drive surface are utilized such that are laid side-by-side, with small gaps being placed between the tracks so that they do not overlap. This is crucial as the gaps severely affect the overall areal density of the drive (a measurement of the amount of data that can be stored on a given unit of physical space on storage media, in gigabits per square inch). However, the CMR takes an upper hand in that data can be constantly written on an existing track as it does not affect other tracks undergoing other processes. Just like the image below, each car is parked side-by-side and internal item is unique without overlapping.
Shingled Magnetic Recording (SMR)
SMR is a fairly new technology exploits the benefits of the write head being larger than the read head. Tracks are partially overlapped on each other, making it such that the areal density is being efficiently utilized. This increases the overall storage capabilities of the drive, which can benefits users. Nonetheless, this advantage comes a great cost, it that it heavily affects the drive performance in a negative way. When data is written to an SMR drive, it will be allocated to an empty storage area instead of onto an existing track due to the architecture of the technology. When in idle, the drive will clear old data such that it has space for a future influx of new data: which makes this idle time crucial for a SMR drive to function. If the SMR drive is constantly being accessed with little to no idle time, the drive is unable to reorganize the tracks, resulting in a drastic drop in drive performance. For example, the picture below with 3 dancers. They are close and overlap with each other, image if they have to maintain this situation in daily life....
While this knowledge may have helped you in better understanding how your data is stored, please do not strive to conduct any form of repairment on your hard drive should it malfunction. You can never be sure what the problem is without firsthand experience and the appropriate equipment. At EHDR, we reveal the truth and only the truth to our customers, diagnosing the problem and swiftly resolving it.
EHDR, We Left No Data Behind.