Tape storage devices have their own unique history of advancement in the technical field. This type of data storage first appeared in the middle of the 20th century and has established itself as a permanent device for writing, reading and storing data.

A tape drive or tape drive is a storage device that operates on the principle of magnetically capturing data on a tape-format medium. After recording data, you can use it for various purposes, and the principle of operation is no different from a household tape recorder.

Today, tape drives are still widely used in some areas. The main purpose is to write and read data, as well as copy and archive them. Recording occurs by storing information, recording it on the drive in parallel along all tracks. When a magnetic tape drive is operating, the tape itself can move in both directions. In essence, the workflow is reminiscent of using a tape recorder, since at the end of the recording, when the tape runs out, the machine moves it in the opposite direction.

The amount of storage information depends only on the footage of the magnetic tape itself. It is the length of the tape that determines the size of the data record.

In the middle of the 20th century, the Eckert-Mauchly Computer Corporation recorded computer data on a tape drive for the first time, and the UNIVAC I computer participated in this.

The information carrier was Vicalloy, which was made of a thin strip of metal 12.65 mm wide, consisting of nickel-plated bronze.

Before hard drives appeared, tape drives were firmly established in computers, serving as the main and long-term storage medium. Later, this kind of storage was used only in cases where the data was rarely used. Tape drives then became portable storage for huge amounts of data.

The very first machine, which appeared in 1951, was called UNISERVO and could store a volume of data equal to 224 kilobytes. This drive used nickel-phosphorus bronze as tape materials.

The following year, IBM released a model with seven tracks on a tape whose composition became plastic. Such a tape stored six bit bytes and one parity bit.

In 1958, a more advanced model appeared with separate heads for writing and reading. The improvement was that the computer could read data after it had been written. There is information that a museum in California stores information on such a drive.

The nine-track tape appeared in 1964. The operating principle is the same as the 1952 model - 8 bit bytes and a parity bit.

Over the ten years between 1970 and 1980, many models appeared with the following innovations:

As of 2014, there is already a model that supports working with LTFS technology, operating according to the file scheme. That is, the device directly provides access to the necessary information, avoiding complete scrolling of the tape. The data volume has increased to 10 terabytes. Today, there are drives with large amounts of memory that are used on an industrial scale.

Since in the last century industrial computers could occupy an entire medium-sized room, the use of magnetic tape drives (NMTs) was widespread.

This type of tape drive was most popular in the USSR in the 70-80s of the last century.

Using an audio cassette

A cassette for a tape recorder has the same principle of operation. It can also be called a tape data drive. Having a primitive tape recorder in the house, anyone could record songs and listen to music.

Until the mid-90s, some types of computers could work with storage devices such as audio cassettes.

Current streamers have the ability to connect using a high-performance SAS interface, which is capable of providing data transfer rates from three to six gigabits per second. Older IBM models were connected via a FICON connector.

Modern representatives of magnetic storage devices adhere to standards called LTO. IBM introduced the LTO-5 TS2350 tape drive (streamer), which has two SAS connectors and one port for Internet access.

Working with multitasking and multi-user operating systems seems to be the simplest way, that is, using commands such as tar and mt. However, with the Mac operating system, the first command is not able to work with streamers, and the second command is simply absent. The main operating systems designed to work with magnetic tapes are Linux and Mac OS X.

For a wide range of operating systems there are special programs to serve modern streamers. Since 2010, IBM has been working on bringing tape drives to Windows.

Description of the tape library

The operating principle of such a library is that it operates simultaneously with several tape drives. Libraries of this scale are completely robotic. Such storage facilities work with cassettes marked with a bar code, which are retrieved by a robot according to a given program.

Compared to disk media, this type of data storage is much more profitable, since maintaining a tape library requires less energy consumption, and the total cost of the equipment is much lower than its disk counterparts.

Pros and cons

Among the advantages, as mentioned above, are the low cost and maintenance of this type of storage. A positive aspect is the possibility of endless data recording, that is, the memory capacity is almost unlimited. Due to monotonous operations and mechanical structure, tape drives can last for quite a long time, namely decades.

Unfortunately, there are also disadvantages of using a tape library - this is the low speed of data access. The fact is that in order to read certain information, the tape needs time to scroll to a given place. The same thing happens if you activate several requests at the same time.

Despite the low resource consumption, the cost of the streamer itself is very high, so the price of the recording device is one of the disadvantages.

Making a request

Modern streamers: choosing a tape drive

False sense of security

It seems that the worst predictions are now becoming reality: for many users, data backup is no longer so important. On the one hand, the solutions on the market are often too expensive - at least at first glance. On the other hand, the ubiquity of RAID arrays on servers gives a false sense of security. The result is disastrous: a series of errors - and the data is lost.

The purpose of redundancy is to protect the data and system from a range of potential disasters. Among them, we note software errors, hacker attacks, viruses, hardware failures or many other nightmare scenarios.

Sometimes a simple power outage or voltage drop in a circuit can instantly destroy the most powerful RAID array.

However, we should not forget that the most common cause of data loss lies in the wrong actions of the user himself. For example, the accidental deletion of seemingly unnecessary data may only be noticed after a few days or weeks - and then it is too late to try to restore anything.

To effectively combat all these risks, users (and administrators) should take data backup seriously. Vital information should be stored on multiple systems and, better yet, in different buildings. This approach allows us to anticipate even natural disasters such as fire or flood.

Different approaches

If your data arrays do not exceed 4.7 GB, then you can use rewritable DVD+RW or protected DVD-RAM. If you need large-volume media, then the only choice is hard disks and streamers that can handle volumes of hundreds of gigabytes. However, hard drives are too heavy for frequent use and too sensitive to physical impacts (dropping to the ground, shock, etc.). On the other hand, hard drives have high transfer speeds.

In fact, this is why a sound data backup strategy still relies on tape drives. You should back up the tape at least once a week and store it in a home safe or even a safe deposit box. Also, do not use tapes more often than the manufacturer recommends.

The purpose of this approach is not only to back up existing data, but also to create a snapshot of the working system. As a result, the user can always roll back or use the snapshot as a reference if the data has been modified.

There are many standards of storage systems on the market, from "tiny" to "simply huge" - it all depends on your needs. Look at the variety of formats and technologies: QIC, Travan, 8 mm, Mammoth, AIT, DLT, SDLT, ADR, LTO and VXA. But don't worry. We will discuss all formats and help you find the right solution for your case.

Does disaster recovery really work?

What's the point of backing up data every day for months if you can't fully restore it in the event of a disaster? The rule of any security system is: always conduct drills so that a “fire” does not take you by surprise. Will RAID 5 work as it should? Remove the hard drive from the array and check the integrity of the data after the reconstruction process. The same applies to solutions on streamers: run a test and fully recover the data - will you get the desired result?

Given today's complex backup programs, it is necessary to check the complete recovery of the computer, including operating system. Remember that backup only makes sense if it allows you to reliably restore data.

Streamer formats: overview

Yesterday and today: SLR75 cassette versus Mini-QIC80. The size of an SLR cassette is largely due to the length of the film, which can vary from 94 to 351 meters.

Spiral scanning allows for the best use of available “space”, but it is slower and more prone to defects than linear options. Source: Exabyte

In general, there are two ways to record on magnetic tape: linear, in which data is recorded from the beginning of the film to its end, or diagonal, the so-called “spiral scan”. In either case, multiple parallel tracks are written to the tape to make full use of the available bandwidth.

Spiral scan came to streamers from the world of VCRs and is used most often in DAT, AIT and VXA systems. Since constant read or write speeds are virtually impossible to achieve, spiral scan devices are much slower than their linear counterparts (due to continuous synchronization with changing data streams). But they can make more efficient use of available tape space, resulting in greater data capacity for helical scan devices.

Similar to VHS systems, the tape exits the cassette and is stretched around a spindle that houses the read and write heads. It is quite natural that this procedure has a mechanical effect on the tape - moreover, than in linear recording devices, where the tape “sits” tightly in the cassette.

Data compression: what a optimist!

When choosing a streamer, you should take a very, very close look at the cassette capacity, since manufacturers often evaluate their solutions taking into account 2:1 compression. Sometimes they can increase the compression ratio to even 2.5:1. However, it should be remembered that such a compression ratio can only be obtained on well-packed data: office documents, databases or source texts programs. The more media files you back up, the lower the overall compression ratio will be.

Already compressed JPG or MPEG files are unlikely to be compressed further, unlike TIF images or WAV files. When in doubt, you should always consider the smaller physical capacity.

Mini-QIC/floppy streamers

The QIC format appeared back in 1972, when the manufacturer 3M needed a solution for storing large amounts of data. At that time, people were not yet particularly concerned about redundancy problems - the primary need was drives with large volumes. Let us remember that hard drives were incredibly expensive back then and there was no commercial use for them yet. For example, the IBM Winchester Project, which began in 1973, did not produce the 5 MB hard drive until 1979. Due to the relatively low price of devices at that time, the QIC standard was widely accepted.

In general, the abbreviation QIC stands for Quarter Inch Cartridge, which refers to the width of the magnetic tape. The most widespread compact cassettes in those years were DC2080 and DC2120. In addition, at that time there were many film standards, which contained from 20 to 50 tracks. In the early 1990s, QIC tape drives with an interface for a disk drive controller became popular, although they were not very pleasing to consumers with their performance (about 35 kB/s). Note that today any DSL connection to the Internet works even faster.

Unfortunately, there are compatibility issues between different devices led to the fact that floppy streamers were suitable only for semi-professional use.

Travan

The Travan standard is also based on QIC and is an attempt to bring clarity to the chaos of over 120 QIC standards. Technically, Travan tapes are far superior to the QIC variants as they have been specifically designed for long-term storage and high reliability. But for the same reason, Travan cassettes are more expensive.

With the introduction of the first Travan standard, tapes immediately became significantly longer, resulting in Travan cassettes being slightly larger than Mini-QIC. If you see the abbreviation NS, it refers to Travan systems from Imation, which differ from 3M-Travan in hardware compression. Good Travan tape drives support the SCSI protocol specifications, which allows relatively quick access to the contents of the tape.

DAT

DAT stands for Digital Audio Tape. But it is not music that is recorded on the tape, but data in the DDS (Digital Data Storage) format. DAT film is 4mm wide and, unlike QIC and Travan, uses helical scan. Therefore, DAT streamers cannot be called very fast, but they cope well with their task of backing up large amounts of data. In addition, their prices differ from QIC and Travan devices by at least two times.

The worst feature of DAT is its high sensitivity. The complex route for removing film from the cassette and considerable frictional forces (they are created from the contact of the spindle with the film) lead to wear and aging. In addition, the read and write heads quickly become misaligned, resulting in frequent errors.

8 mm / Mammoth / AIT

8mm wide magnetic tapes were originally developed for video. Like DAT, 8mm film also uses helical scan, although it provides a much higher capacity.

8 mm film is used in two formats: Mammoth from Exabyte and AIT, a solution from Sony and Seagate.

In addition to high capacity, a key advantage of AIT systems can be considered an additional memory chip in the cassette called MIC (Memory in Cassette - “memory in cassette”), which contains a kind of table of contents of the cassette. As a result, there is no need for multiple search processes - the streamer can immediately move to the desired position. At the same time, AIT drives do not need to read sector information from the tape. They accurately calculate the position based on MIC information. This feature also helps ensure that the correct film is used.

SLR

The abbreviation SLR stands for Scalable Linear Recording. The standard uses a robust design with a minimum of moving parts to ensure long-term reliability of use. From a technical point of view, SLR is based on the QIC and ADR standards (see description below), using multiple heads. Pre-recorded service tracks allow precise positioning of the heads. In addition, Tandberg emphasizes the ability to withstand changes in temperature and humidity.

DLT

Just by deciphering the abbreviation DLT (Digital Linear Tape - tape for digital recording with sequential access), it is clear that a linear recording method is used here. The tape is half an inch wide and is recorded in pairs, track by track. Each of the 128 or 208 tracks is the same length as the entire tape. After rebuilding the heads, the process continues in the opposite direction.

DLT streamer technology is significantly different from others: here, the tape also unwinds from one reel before being wound by another reel. However, the target reel is not in the cassette, but is part of the drive. Thanks to the clever laying of the tape, friction is minimized, so the film never experiences heavy loads. As a result, wear on DLT cassettes is minimal, although it is still worse than, for example, SLR.

Unlike other formats, DLT has automatic cleaning capabilities and uses special electronic components to ensure long runtime.

Super DLT

The SDLT standard is designed to achieve a single goal - even larger capacities. Thanks to a combination of optical and magnetic recording methods (LGRT - Laser Guided Magnetic Recording - magnetic recording with laser guidance), it provides high accuracy.

For more information contact www.dlttape.com .

ADR

The ADR (Advanced Digital Recording) standard is promoted by Philips and its On-Stream division. A unique feature of this 8mm film technology is the simultaneous recording/reading of eight of the 192 tracks of data, allowing for high bit rates at low tape speeds.

As a result, we get a wonderful side effect - relatively low mechanical wear. In addition, ECC error correction can be applied both horizontally and vertically. For example, 24 tracks out of 192 on a tape may be damaged, but no data will be lost.

Without compression, ADR tapes can store up to 25 GB. There are plans to increase the capacity in the future.

LTO

The LTO (Linear Tape Open) standard was developed as an alternative to DLT. Linear notation and set technical features make the LTO standard very attractive, and it is based on reliable technology.

The main iterations of the standard are Accelis and Ultrium, which can be easily licensed. Ultrium delivers impressively high capacity and data transfer speeds.

VXA

By recording in batches instead of tracks, helical scanning does not impact VXA speed as much.

It’s been a while since we talked about classic data backup systems – tape libraries. After all, no matter what some storage vendors (focused exclusively on disk devices) say, tape libraries remain the most important means of backup and long-term archiving. In 2012, North American CIOs were surveyed about their tape plans. So, 87% confirmed that they would increase their use or, at a minimum, leave it at the same level. Who is the leading manufacturer of tape libraries? According to storagenewsletter.com, HP is the leader, selling 31% of devices in 2012, almost twice as much as its nearest competitor. Despite the fact that HP supports DDS and LTO standards, today we will only talk about the latter, because LTO sales account for 94% of all drive types.

In 2013 the lineup has changed quite a lot compared to last year. Firstly, at the end of 2012. A new generation of LTO-6 drives was released, which made it possible to increase the capacity of one cartridge more than twice as compared to LTO-5 - up to 6.25 TB (including compression), and the recording speed increased almost one and a half times - up to 1.44 TB / hour. All this made it possible to significantly increase storage density, while the cost per terabyte decreased.

Starting with the fifth version of the Ultrium standard, it became available file system Linear Tape File System (LTFS) on tape media. This file system allows LTO-5 and 6 cartridges to be used on external tape drives as USB device(flash memory) and with an external drive. LTFS uses the first tracks of the tape for the file system index.

An exclusive feature of HP Ultrium tape drives, the system compares and adjusts the tape write speed with the incoming data stream - allowing the device to dynamically and continuously synchronize its speed with the data transfer rate from the server. This feature improves the speed of reading and writing data to the tape and improves the reliability of both the drive itself and the tape cartridge. The reliability of the drive and cartridge is also ensured by a special mechanism for automatically positioning the cartridge when loading it and a mechanism for automatically cleaning the read/write heads.

Another new useful functionality is HP’s proprietary utility – TapeAssure. It improves the efficiency of tape libraries and cartridges by proactively monitoring the status, performance, utilization and health of drives and backup media. Given software available for free download.

HP sells both individual drives (they can be installed in special rack shelves) and tape libraries. Tape libraries are designed for automated data backup. Simultaneous use of multiple tape drives increases library performance and reduces the time required for writing and reading backup copies. Libraries are equipped external interfaces SAS, SCSI or Fiber Channel, providing the ability to simultaneously connect to multiple servers and integrate into a SAN storage network.

Automated backup products include entry-level Autoloader 1/8 G2 and MSL2024 and MSL4048 tape libraries, mid-range MSL 6480 tape libraries and enterprise-grade ESL-G3 tape libraries.

The autoloader supports only one SCSI, SAS, or FC tape drive and has only 8 tape slots.
MSL series libraries (including models: 2024, 4048, 8048, 8096) can support several tape drives (with SCSI, SAS or FC interface) and have significantly greater capacity due to the increased number of slots.
Models MSL8048 and MSL8096, as well as the EML line, are being discontinued and are being replaced new model MSL 6480, which was announced in the summer of 2013. and supports scaling up to 7 modules within one rack. Each module supports up to 6 half-height drives, up to 80 cartridges, up to 240 TB (1:2.5 compression). When installing 7 6480 modules in one server rack, you can get up to 42 drives per rack with a total cartridge capacity of up to 3.5 PB and write speeds of up to 60 TB/hour

HP StoreEver MSL Tape Libraries

MSL libraries support the ability to create several virtual libraries (partitions) within one physical device. Also, to increase capacity and speed, you can combine two MSL libraries into one logical library using a special mechanism installed in the tape drive slot.

Hi-End class libraries - ESL-G3 - have only case design in separate modules (cabinets). These libraries can be scaled horizontally, i.e., using special mechanisms, up to 16 modules can be combined into a single library. This single library will have a common tape pool available to any tape drive, regardless of which of the individual ESL-G3 library modules it resides in.

The ESL-G3 library can support up to 12 tape drives and up to 306 slots in the control module. The expansion module supports up to 12 tape drives and up to 444 slots. In its maximum configuration, the ESL-G3 library can support up to 96 tape drives and more than 11,000 slots. ESL-G3 only support FC interface - 4 Gbit/s or 8 Gbit/s.

The ESL-G3 offers high availability with tape drives, redundant fans, and hot-swappable power supplies. In addition, ESL-G3 libraries support the ability to reserve access channels to both streamers and the library robot.

In June 2013, High Density Expansion Modules were announced for ESL-G3 models, holding up to 780 cartridges. With the use of these expansion modules, the number of supported slots has almost doubled from 7100 to 11600, which is equivalent to 72 PB of data (including compression). This density was achieved thanks to a change in the design of the modules - now the slots are located on a rotating drum along which the robot slides. Robots in the ESL-G3 library now operate in Active/Active mode (in previous Active/Passive models), which has increased the library's performance.

Thus, the updated range of HP tape libraries is perfect for organizations of any size - from a small office to a corporate data center.