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Data Storage: What is the future?



Most recently, we talked about the work of those services . support our cloud service 1cloud and offered a "Friday format", allowing you to get acquainted with the device service Netflix and scientists' estimates regarding the prospects in the field of AI .

Today we decided to look at the state of affairs in the field of data storage, and tomorrow you will find the traditional "Friday format" with an analysis of the topic of "cloud robotics" and related fields of activity.
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Already "on the threshold"


In 2014, Seagate announced its new Kinetic HDD disk drive with an Ethernet interface, the performance of which is several times higher than the performance of all existing products at that time.

Each Kinetic HDD drive has two Gigabit Ethernet ports, each with its own IP address, and the Kinetic Open Storage platform allows applications and hosts to communicate with each other directly via hard drives using TCP / IP data center infrastructure using an open API.

Such technology can seriously transform the infrastructure of data centers and the IT industry as a whole. Direct connection of disks with applications will make it possible to abandon controllers, file systems, and even RAID arrays. This will definitely contribute to the distribution of distributed databases like Cassandra.

Also in 2014, HGST unveiled a new Ultrastar He8 SATA Ultra hard drive to the general public. The main technical solution was filling the camera with rotating disks with helium.

And in September 2014, Western Digital introduced the first 10 TB hard drive using this technology. Since instead of air there is helium in the disk chamber, the disks are much easier to rotate, because of this they heat less and can be located closer to each other.

At the moment, such disks are not used in commercial or professional broadcast video servers, however, new helium HDDs consume 33% less electricity. This will increase disk density in data centers, as well as reduce operational costs and space occupied by devices.

As for recording technologies, another technique capable of breaking into the market in the near future is recording with overlapping tracks (SMR - Shingled Magnetic Recording) - this is a special storage technique; when recording information onto a disc, tracks overlap each other. This allows you to increase the number of tracks on each plate and reduce the distance between them, which in turn leads to an increase in disk capacity by 25%.

However, there are several difficulties. For example, in order to overwrite or update information, you need to update not only the desired fragment, but also the data on the last tracks, since the recording head of such disks is wider than the reading one and captures the data on the adjacent tracks. All this leads to poor write performance.

The development of SMR technology involved in both Seagate and HGST. As for HGST, the company produced a 10 TB helium disk using this technology. It was intended to "cold" data storage.

Perspective development


For about 50 years, manufacturers of magnetic drives have used a method called parallel magnetic recording (LMR - Longitudinal Magnetic Recording), in which the magnetization vector for each bit of information is parallel to the surface of the carrier (film or disk).

While in the historical retrospect the surface recording density doubled approximately every year, eventually the growth rate slowed down, and over the past ten years the longitudinal magnetic recording reached the fundamental limit of recording density, which was about 100-200 gigabits per square inch.

This limit is called the "superparamagnetic limit", due to temperature fluctuations at the time of the polarization of the granules (state changes) while writing to the device. The effect of paramagnetism leads to the occurrence of stray fields and incorrect orientation of charges on the disk plane - “bit errors”.

To expand the capabilities of the HDD, a perpendicular magnetic recording (PMR - Perpendicular Magnetic Recording) was invented, capable of recording 1 TB of data on a disk plate: the bits were polarized “perpendicular to the plane” rather than “parallel”.

Initially, PMR technology was seen as a temporary solution, but it began to be used everywhere. However, PMR has all the same problems with read and write stability as with the LMR.

Therefore, Western Digital and Seagate are working on discs using thermally assisted magnetic recording technology (HAMR - Heat Assisted Magnetic Recording), which can be used to create 3.5-inch discs with a capacity of up to 60 TB.

HAMR is designed to replace the PMR and uses a small laser to heat the part of the disk on which it is planned to record. This allows you to reduce the size of the magnetic region that stores one bit of information, and increase the stability of data storage.

However, all the above technologies are the precursors of the new multi-layer 3D-recording. Back at the end of 2013, researchers from Florida International University showed that 3D recording has tremendous potential and allows you to create huge storage media.

In ML-3D, instead of one magnetic layer, three are used at once, between which an insulator is laid. For recording, a special magnetic head is used. Reading is carried out using a weaker magnetic head, by calculating the vector sum of nano-columns. The figure below shows sets of bits formed by a magnetic field of different strengths and directions and grouped into nanocolumns.



Another interesting and promising technology is the phase change memory (PCM - Phase Change Memory), which is considered as a future replacement for NAND flash memory technology. PCM uses chalcogenide, a material capable of transitioning from a crystalline to an amorphous state when heated.

Cell status changes can be made about a million times, which significantly exceeds the parameters of commercially successful NAND cells in SSD-drives of the corporate level (about 30,000 rewriting cycles).

The PCM memory problem is high write latency, but IBM has demonstrated that a hybrid device with PCM, NAND and DRAM on one controller can work 275 times faster than a regular SSD device. IBM estimates that the first commercial products based on hybrid PCM technology will be available in 2016.

Despite the fact that an increasing number of companies are working on increasing the capacity of hard disks, there are developments designed to increase the capacity of optical disks. Active work on holographic disks (HVD) has been underway for at least a decade. In 2011, GE introduced its holographic repository: DVD-sized discs that can fit up to 500 GB of data in tiny holograms.

To do this, use two lasers: red and green, combined into one beam. The green laser reads data encoded as a grid from a holographic layer close to the disk surface, while a red laser is used to read auxiliary signals from a conventional layer located in depth.

Recently, however, little has been heard about HVD technology, and one of the main developers, InPhase Technologies, went bankrupt in 2010. However, I would not like the technology to remain “underdeveloped”, because these disks are fairly reliable and it is believed that they can store data for 30 years.

Far future


In May 2014, IBM and Fujifilm announced a tape storage device that can store 85.9 billion bits per square inch of magnetic tape. This density allows you to create cartridges with a capacity of up to 154 TB, which is 62 times greater than the capabilities of LTO-6 cartridges.

To obtain such a high density, Fujifilm experts have developed Nanocubic technology , thanks to which it is possible to form an ultrathin magnetic layer. The thinner the magnetic layer, the more magnetized domains are placed on a unit area of ​​the magnetic tape. Commercial sales of technology may appear over the next 10 years.

However, the most promising and promising future technology is DNA-based storage .



Perhaps this is one of the strangest technologies of the future. In 2012, researchers from Harvard were able to encode a book of 53,400 words, eleven JPEG images and one JavaScript program into DNA.

DNA offers an incredible recording density of 2.2 petabytes per gram. This means that a teaspoonful DNA disk can fit all the data that exists in the world — every song, every book, every video. In addition to its small size, another advantage of DNA storage is durability. According to Harvard’s George Church (George Church), you can leave a DNA drive anywhere, even in the desert, but the data will remain on it even 400,000 years later.

The process of synthesis of DNA sequences is similar to stringing pearls on a string. In this case, the information is encoded as traditional zeros and ones. These values ​​are assigned to certain chemical components, monomers, which by means of chemical methods are linked in one chain, forming polymers. To read the recorded information, it is enough to use a mass spectrometer - a device for reading DNA sequences.

To test how long data can be stored in DNA, scientists coded 83 kilobytes of data (according to New Scientist, the coding cost of 83 kilobytes was $ 1,500). The material was the Swiss Federal Charter of 1291 and the Archimedes palimpsest. The choice of these documents, according to scientists, shows not only the potential applicability of the method, but also its historical importance. According to representatives of ETH Zurich, these data will remain unchanged for a million years (if the DNA is subjected to freezing).

The biggest obstacle that does not yet allow the use of DNA to store information in practice is time . Even using modern decryption technology, reading a DNA molecule takes many hours — several orders of magnitude more than reading a regular file on a computer. Because this type of storage is not suitable for frequently used data. Moreover, scientists still enter information into artificial DNA and only then place it in a bacterium.

As you know, not all technologies are beginning to be used everywhere and are becoming widely available. But a team of researchers from the United States recently made a breakthrough, which showed that you can store data in the so-called "soft substances".

According to a new study, microscopic particles in a liquid can be used to encode the same zeros and ones, just like in modern hard drives. In theory, clusters of such particles can once store up to 1 TB of data in a tablespoon of liquid.

The term “soft substance” can refer to liquids, polymers and even biomaterials. All these substances have predictable behavior under the influence of different temperatures - they change shape at the molecular level. The team responsible for the study used a certain type of colloidal suspension with special nanoparticles that retain their properties.

Such particles when heated are organized in groups. In this particular case, the nanoparticles were collected in groups of four or more pieces, while one of them was the center. The size of the ligaments barely exceeded 5 micrometers in diameter, but the team of scientists was able to visually note the changes taking place.

Clusters of four particles can be in only two states, which can be encoded as zero and one. However, this is just the first step towards “liquid storage”. Now you need to find a reliable way to form clusters in large volumes of liquid and quickly read the recorded data.

But probably the most advanced technology of the future may be quantum storage. Today, scientists are studying ways to store data using the laws of quantum physics - that is, they are trying to encode information using the controlled orientation of the electron spin.

At the moment, this way you can save a small amount of data for a very short time (less than a day), but if everything works out, then perhaps due to quantum entanglement we will be able to instantly synchronize data between two points.

PS We in 1cloud consider a variety of topics in our blog on Habré - a couple of examples:


And we talk about our own cloud service :

Source: https://habr.com/ru/post/281563/

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