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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 important information should be stored on several 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 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 HDD 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 any case, several parallel tracks are recorded on the tape in order to make full use of the available throughput.

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, helical 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 degree of compression can only be achieved on well-packed data: office documents, databases or program source codes. The more media files you back up, the lower the overall compression ratio will be.

Already packed JPG files or MPEG can hardly be compressed any further, unlike TIF pictures 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, led to the emergence of hard drive by 5 MB only in 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, compatibility issues between different devices meant that floppy streamers were only suitable 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. Travan belts are technically 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.

	TR-1	TR-2	TR-3	TR-4	TR-5	TR-6
Capacity	400 MB	800 MB	1.6 GB	4 GB	10 GB	20 GB
Maximum speed reading	125 kB/s	125 kB/s	250 kB/s	1.16 MB/s	1.83 MB/s	4 MB/s
Number of tracks	36	50	50	72	108	144

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.

Standard	Capacity	Maximum reading speed
DDS	2 GB	550 kB/s
DDS-1	2 GB	1.1 GB/s
DDS-2	4 GB	1.1 MB/s
DDS-3	12 GB	2.2 MB/s
DDS-4	20 GB	4.8 MB/s

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.

Standard	Capacity	Maximum reading speed
8mm	3.5 GB	533 kB/s
8mm	5 GB	1 MB/s
8mm	7 GB	1 MB/s
8mm	7 GB	2 MB/s
AIT-1	35 GB	4 MB/s
AIT-2	50 GB	6 MB/s
AIT-3	100 GB	12 MB/s
S-AIT	500 GB	30 MB/s
Mammoth	20 GB	6 MB/s
Mammoth 2	60 GB	12 MB/s

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.

	Capacity	Maximum reading speed
SLR3	1.2 GB	300 kB/s
SLR4	2.5 GB	300 kB/s
SLR5	4 GB	380 kB/s
SLR7	20 GB	3 MB/s
SLR50	25 GB	2 MB/s
SLR60	30 GB	4 MB/s
SLR75	38 GB	4 MB/s
SLR100	50 GB	5 MB/s
SLR140	70 GB	6 MB/s

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 routing of the tape, friction is kept to a minimum, so the film never suffers 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.

Standard	Capacity	Maximum reading speed
DLT2000	15 GB	1.25 MB/s
DLT4000	20 GB	1.5 MB/s
DLT7000	35 GB	5 MB/s
DLT8000	40 GB	6 MB/s

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.

	SDLT 220	SDLT 320	SDLT 600	SDLT 1200	SDLT 2400
Capacity	110 GB	160 GB	300 GB	600 GB *	1.2 TB**
Maximum reading speed	11 MB/s	16 MB/s	36 MB/s	50 MB/s	100 MB/s
Cartridge	SDLT I	SDLT I	SDLT II	SDLT III	SDLT IV
* 2005, ** 2006

For getting additional 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.

Capacity potential		Reading speed potential
Today	25 GB		2 MB/s
Film length	2x	Film speed	3.6x
Film width	3x	Parallelization	3x
Track Density	4x	Track Density	3x
Bit Density	3x	Bit Density	3x
Maximum (approx.)	3.6 TB	Maximum (approx.)	130 MB/s

LTO

The LTO (Linear Tape Open) standard was developed as an alternative to DLT. Linear recording and many 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.

	Ultrium-1	Ultrium-2	Ultrium-3	Ultrium-4
Capacity	100 GB	200 GB	400 GB	800 GB
Reading speed	20 MB/s	40 MB/s	80 MB/s	160 MB/s

VXA

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

Addressed primarily to those who have just begun to think about the need to create backup copies. As a rule, at this stage three problems may await you.

The first is that in your mind tape drives are vaguely associated with the group Dr. Alban or any other sign of the distant 90s. Now, in an age of almost total crowding of the data storage market with various devices with reusable recording, we often discount old proven technologies. At the same time, the idea of reuse forgets that the cost of storing a gigabyte of data with tape drives cannot be compared with any other type of media.

The second problem is when you are really unaccustomed (or never got used to) working with something other than hard drives or flash drives. This is where an external version of the drive, connected via USB, will come to our aid: it will be just another cute box on your desk. If the procedure for disassembling/assembling a computer does not seem difficult for you, then you can save a little by purchasing a device with internal mounting, connected via the SAS interface.

And then the third wave hits us - how to organize work with the device, since you have never encountered it before? A complete set comes to our aid software- HP Data Protector Express Single Server Edition. Most likely, this software will be able to satisfy 90% of the needs of a novice user, which is what we need.

Now, what does the seventh generation bring to us?

Small and smart!

It would seem that what can be improved in a storage device, the first ancestor of which appeared in the early 80s of the last century? After all, everything was invented a long time ago!

But technology and technical thought do not stand still, and here is the result:

Quite an expected increase in capacity. According to the good old tradition - double, so now on a ribbon that resembles in shape and size Matchbox, fits up to 320 GB (with 2:1 compression).
increased write/read speed. Data flows into this box at speeds of up to 86 GB/hour, i.e. The entire cassette is recorded in less than 4 hours.
The device's power consumption has been halved. This once again proves that the pursuit of ideality bears fruit, which is very pleasant for the user.

What is customary to remain silent about

Ask yourself this question: when did you start thinking of buying and using a tape drive not as a waste of money and time, but as a great resource in the event of a server problem? The common answer to this question is: never. Even after you've been through a few unpleasant incidents, the server is down, the office work is down, and your desk is besieged by crowds of colleagues with pitchforks and torches.

But in vain! After all, owners of all HP tape drives have the opportunity to simply protect their server assets using the One Button Disaster Recovery (OBDR) function. Thanks to it, your Proliant, which has suffered from damage to the OS, applications or data, can boot from the latest backup cartridge, like from a DVD-ROM, and be completely restored to its pre-crash state. All this at the touch of a button. In this case, downtime is reduced to just a few minutes, so your employees will only have to drink tea one more time.

As a result, the current generation of HP tape drives, along with perhaps the most sophisticated technical foundation of any type of storage device, has all the attributes that will allow them to fit into the most modern infrastructure of your network.

And now, as always, we are waiting for your questions)

30.06.2010

Yuri Levin, NStor

In 1997, the three largest manufacturers of magnetic tape drives - IBM, HP and Seagate entered into an agreement, which resulted in the creation of a new open technology for tape drives, Linear Tape Open, which formed the basis of LTO tape drives. The creation of such technology made it possible, firstly, to ensure mass production of compatible storage media from different manufacturers, secondly, to expand the range of created storage devices and thirdly, to ensure protection of the investments of partners and clients. Two formats have been created based on LTO technology - Ultrium And Accelis.

1. Devices Accelis, focused on minimum access time and maximum speed. Moreover, to obtain a minimum access time, the initial position of the tape in the cartridge is not the beginning, but the middle of the tape. This specification is not currently used.

2. Devices Ultrium oriented towards maximum capacity. The design of the cartridge and drive is reminiscent of DLT-SDLT, but the smaller height dimensions later gave the format an undeniable advantage, which made it possible to push the DLT-SDLT-"DLT-S4" format out of the 1/2U autoloader market.

Features of LTO technology:

Support large quantity parallel channels on tape

Half-inch wide film (like Digital Betacam VCR) provides incredible durability, wear resistance, tensile strength and minimal runout angle.

High density of recording information on tape

Improved information compression algorithm - recognizes compressed data and disables compression, 2:1 compression algorithm

Dynamic movement of data from damaged areas on the tape, when the servomechanism or one of the read-write heads breaks down.

LTO-CM (LTO Cartridge Memory) is a chip for storing information about the placement of data on the media. Uses a contactless radio interface for data transmission. High data integrity during recording is achieved thanks to two-level error correction. The error control and correction algorithm provides reliable recovery information even if data is lost on one of the eight tracks. In addition, there is the ability to read while writing - RWW (Read While Write), which allows you to verify data in real time. Dynamic rewriting of bad blocks ensures high-quality copying of information even if one or more heads fail. The dual servo system guarantees (due to redundancy) the normal functioning of the drive even in cases of failure of one of the systems or damage to part of the servo information recorded on the magnetic tape.

All Ultrium LTOs feature Write Once Read Many (WORM) technology

Support for a large number of parallel channels on the tape, up to 8 in the first generation and up to 64 in the fourth

LTO Ultrium devices combine the advantages of the open LTO format at an affordable media price, with the ability to be widely integrated into both single-unit autoloaders used in small businesses and enterprise-level tape libraries used in data centers. Also, they are easily integrated into server and other designs thanks to various SCSI, SAS, FC interfaces and form factors, for example, in HP Blade servers. Compatible with almost all operating systems Microsoft systems® Windows, HP-UX, Tru64, Red Hat Linux, SUSE Linux, IBM-AIX, Sun Solaris makes the format even more attractive and flexible. At the same time, the DLT-SDLT standard will be inferior in terms of the number of slots in devices, since LTO cartridges are slightly smaller in size than SDLT (DLT-S4) and require less space to place them in tape libraries. All LTO-Ultrium tape drives support WORM, write once, read many.

Currently, the main manufacturers of LTO-Ultrium are Hewlett-Packard, IBM, Quantum, Tandberg. To date, 4 generations of LTO format devices have been released:

LTO-1 (Generation-1), (100/200GB)

The first generation tape drives LTO-1, Ultrium 215 cache 16 Mb (7.5/15 MB/sec, 100/200 GB), appeared at the end of 2000, it was possible to record on 50/100 GB cassettes, these cassettes were no longer available were used. The second generation of streamers LTO-1 Ultrium 230 cache 16 Mb (15/30 MB/sec, 100/200 GB) came out about a year later, from the previous one, it differed in twice the speed and full-size height, both generations were equipped only with a SCSI interface LVD/SE. The LTO-1 Ultrium 232 64MB cache (16/32 MB/sec, 100/200 GB) is currently being produced; in addition to SCSI, it has an FC interface from IBM.

LTO-2 (Generation-2), (200/400GB)

First generation LTO-2 Ultrium 460 full-height tape drives (30/60 MB/sec, 200/400 GB), equipped with a Wide Ultra 160 SCSI LVD/SE, FC interface Second generation LTO-2 Ultrium 448 tape drives 64 MB cache (24/48 MB /sec, 200/400 GB), equipped with a Wide Ultra 160 SCSI LVD/SE interface, as well as 3Gb/s SAS, 80-pin SCA (SCSI and power)

LTO-3 (Generation-3), (400/800GB)

First-generation tape drives LTO-3 Ultrium 960 cache 128 MB full height (160/320 MB/s, 400/800 GB), equipped with a SCSI LVD/SE, FC interface, and Quantum also has an LTO-3A Drive Gigabit Ethernet option ( NAS). The second generation of tape drives LTO-3 Ultrium 920 cache 64MB (160/320 MB/s, 400/800 GB), equipped with a Wide Ultra 320 SCSI LVD/SE interface, as well as 3Gb/s SAS, FC, 80-pin SCA ( SCSI and power)

LTO-4 (Generation-4), (800/1600GB)

First-generation tape drives LTO-4 Ultrium 1840 cache 128MB full height (160/320 MB/s, 800/1600 GB), equipped with both an Ultra320 SCSI LVD/SE, FC interface and a 3Gb/s SAS interface.

The second generation of LTO-4 half-height tape drives (160320 MB/s, 800/1600 GB is currently only equipped with a 3Gb/s SAS interface. LTO-4 tape drives already have 256-bit encoding built into hardware. Hardware-based data encryption using 256 -bit AES system provides simple and effective protection of sensitive data and prevents unauthorized access to tape cartridges Data Rate Matching (DRM) function Allows the tape drive to adjust the drive speed, from 40 to 120 MB/s (native), allowing for drive streaming, increased performance, and reduced start/stop times, resulting in improved drive and media reliability

LTO-5 (Generation-5), (1600/3200 GB)

Carrier— Ultrium cartridge 105x102x22 mm, older models can read and write cartridges of lower formats.

Compatibility

LTO drives and storage media from different manufacturers are compatible with each other, taking into account the generation.

The LTO standard regulates support in drives for reading 2 generations back and writing 1 generation back (that is, for example, an LTO-5 drive must be able to read LTO-5, LTO-4 and LTO-3 cartridges and write LTO-5 and LTO-4).

	Generation
Parameter	LTO-1	LTO-2	LTO-3	LTO-4	LTO-5	LTO-6	LTO-7	LTO-8
Year of appearance	2000	2003	2005	2007	2010	Plan	Plan	Plan
Physical capacity	100 GB	200 GB	400 GB	800 GB	1.5 TB	3.2 TB	6.4 TB	12.8 TB
Maximum speed (MB/s)	15	40	FH: 80 HH: 60	FH: 120 HH: 80	180	270	315	472
WORM support	No	No	Yes	Yes	Yes	Yes	Yes	Yes
Encryption support	No	No	No	Yes	Yes	Yes	Yes	Yes
Partitioning support	No	No	No	No	Yes	Yes	Yes	Yes
Tape thickness	8.9 µm	8.9 µm	8 µm	6.6 µm	6.4 µm
Tape length	609 m	609 m	680 m	820 m	846 m
Paths	384	512	704	896	1280
Heads	8	8	16	16	16
Lane passes	12	16	11	14	20 (?)
Linear density (bit/mm)	4880	7398	9638	13300	15143
Coding	RLL 1.7	PRML	PRML	PRML	NPML

LTO Ultrium Belt Drive Range

Model	Capacity	Speed	Average cost of storage	MTBF hours	Duty cycle	Average access time	Buffer	Cartridges used
Ultrium 232 (LTO-1)	100/200	16/32	1500	250000	100%	142s	64	LTO Ultium 1
Ultrium 230 (LTO-1)	100/200	15/30	1500	250000	100%	71s	16	LTO Ultium 1
Ultrium 448 (LTO-2)	200/400	24/48	1800	250000	100%	64	64	LTO Ultium 1, LTO Ultium 2
Ultrium 460 (LTO-2)	200/400	30/60	2100	250000	100%	46	128	LTO Ultium 1, LTO Ultium 2
Ultrium 960 (LTO-3)	400/800	80/160	2900	250000	100%	53	128
Ultrium 920 (LTO-3) HH	400/800	60/120	2800	250000	100%	53	64	LTO Ultium 3, LTO Ultium 2, Read LTO Ultrium 1
Ultrium (LTO-4) HH	800/1600	120/240	4500	250000	100%	53	128
Ultrium 1840 (LTO-4)	800/1600	120/240	4700	250000	100%	53	128	LTO Ultium 3, Read LTO Ultium 2, LTO Ultrium 1

LTO Roadmap

Further development of the format seems quite promising, successful engineering solutions combined with the support of such equipment manufacturers as Hewlett-Packard, IBM, Quantum, Tandberg, as well as media manufacturers MAXELL, Fuji, Sony. All these factors allow LTO-Ultrium to be a leader in its class and gain new positions from other formats. There are practically no formats left that can compete with LTO-Ultrium, a combination of factors such as amazing read-write speed, search and reliability of the media and equipment, as well as the cost of 1 GB of information stored on tapes of this format.

2017 REVIEW OF TAPE TECHNOLOGIES: LTO, IBM 3592, ORACLE STORAGETEK T10000

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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.

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 storage media, then the only choice is hard drives and tape drives, which 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.

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.

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 the 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.

Linear method or spiral scan

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.

Data compression: what a optimist!

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.

Unfortunately, compatibility issues between different devices meant that floppy streamers were only suitable 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.

DAT

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.

Standard	Capacity	Maximum reading speed
8mm	3.5 GB	533 kB/s
8mm	5 GB	1 MB/s
8mm	7 GB	1 MB/s
8mm	7 GB	2 MB/s
AIT-1	35 GB	4 MB/s
AIT-2	50 GB	6 MB/s
AIT-3	100 GB	12 MB/s
S-AIT	500 GB	30 MB/s
Mammoth	20 GB	6 MB/s
Mammoth 2	60 GB	12 MB/s

SLR

	Capacity	Maximum reading speed
SLR3	1.2 GB	300 kB/s
SLR4	2.5 GB	300 kB/s
SLR5	4 GB	380 kB/s
SLR7	20 GB	3 MB/s
SLR50	25 GB	2 MB/s
SLR60	30 GB	4 MB/s
SLR75	38 GB	4 MB/s
SLR100	50 GB	5 MB/s
LR140	70 GB	6 MB/s

DLT

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

ADR

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 recording and many 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.

	Ultrium-1	Ultrium-2	Ultrium-3	Ultrium-4
Capacity	100 GB	200 GB	400 GB	800 GB
Reading speed	20 MB/s	40 MB/s	80 MB/s	160 MB/s

VXA

The VXA standard, developed by Exabyte, allows tape speed to be adjusted based on system capabilities, helping to avoid unnecessary stops, rewinds and repeats.

VXA generally breaks long data streams into smaller blocks and writes them to tape in the Discrete Packet Format, which provides increased data integrity. The DPF format uses a buffer to efficiently organize the recording process on tape. In addition, ECC is checked in the horizontal, vertical and diagonal directions for each packet.

Each packet is 64 bytes in size, and each track contains 387 packets. If one of them is recorded incorrectly, it will be recorded again at the nearest possible location.

Thus, the VXA drive operates very efficiently and provides a high degree of data integrity in the event of film defects. Moreover, the reliability of the VXA standard has been confirmed in practice: it is reported that the tapes were restored even after being in water (although we did not test this situation in our laboratory).

Test streamer: Tandberg SLR75

The drive uses QIC 80 technology. Data is recorded linearly onto 192 tape tracks. In addition to them, 24 service tracks are applied to the tape, allowing the positioning of the read and write heads. For better reliability, the cartridge is reinforced at the bottom with a metal plate.

Theoretically, data can be stored securely for 10 years, which would be sufficient under many laws.

The noise level when writing or reading data was low because SLR technology uses a minimum number of moving parts. However, backups are most often performed at night, so noise will not bother anyone.

Inside the drive, the number of moving parts is reduced to a minimum. The illustration shows the read/write head.

The LR75 is recognized by most backup software as a SCSI device. Thanks to the 68-pin SCSI interface, you can easily integrate the streamer into a server environment.

Test scenario: backing up 28.4 GB of data

We collected about 30 GB of various information on the computer’s hard drive. Essentially, our test programs are located there. The number of files reaches 52,000.

Hardware

CPU Intel Pentium 4, 2.0 GHz 256 KB L2 cache (Willamette)

AOpen AX4PE Max motherboard, 845PE chipset

Memory 512 MB DDR400/PC3200, Buffalo Tech.

Controller i845E UltraDMA/100-Controller (ICH4) Adaptec 39320-R, Ultra320 SCSI

Hard drive IBM IC35L060AVVA07

ATi Radeon SDRAM graphics card, 32 MB

Network 3Com 3C905TX, PCI, 100 Mbps

OS Windows XP Pro 5.10.2600 Service Pack 1 Drivers and programs

Dantz Retrospect 6.0 backup software

Graphics driver 5.1.2001.0 (Windows XP Standard)

IDE driver Intel Chipset Installation Utility 5.1.1.1002

DirectX version 9.0a

Resolution 1024x768, 16 bit, 85 Hz

Software systems Arkeia, BrightStor, Dantz and Veritas allow you to turn most streamers into turnkey backup solutions. For our testing, we chose Dantz's Retrospect program.

The future: reducing sources of error

Regardless of the technology used, users themselves are the biggest source of error in IT. That is why modern developments are aimed not only at increasing capacity and transmission speed, but also at creating accompanying security features that will reduce the consequences of errors to a minimum.

That is, even the cheapest streamers will determine the inserted tape and the number of records in order to timely determine the depletion of the tape resource.

Another step is to increase automation of the reservation process to reduce the chance of human error to a minimum. Using robot loaders allows you to back up data onto multiple tapes.

Conclusion

The wide variety of standards, capacities and transmission speeds on the streamer market can easily intimidate the unprepared user. The situation can be further complicated by the need to select an interface or design option.

In addition, the user often has to look for grains of truth in the marketing information of manufacturers who consider their standards to be the best on the market. Therefore, comparing different streamers with each other can be very problematic.

The main point of our conclusion will be this: you will have to carefully study all the standards, each time assessing their suitability for your needs. In addition, the correct choice of backup software is also quite important.

Even in the inexpensive segment of streamers, automatic loaders are appearing today (for example, ValueLoader from Quantum for DLT, LTO and 8 mm). They combine a streamer drive and a magazine for several cassettes. If you install such a device in a 19" rack, you will get a reliable and effective solution - and for only a few thousand dollars. The price is unlikely to seem high to you when you compare it with the damage from losing all your data.

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 model range 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, the Linear Tape file system became available 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 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. This software is 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 to write and read backup copies. Libraries are equipped with external SAS, SCSI or Fiber Channel interfaces, providing the ability to simultaneously connect to multiple servers and integrate into a SAN storage network.

The range of automated backup products includes devices entry level: Autoloader 1/8 G2 and MSL2024 and MSL4048 tape libraries, MSL 6480 midrange tape libraries and ESL-G3 enterprise 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, expansion modules were announced for ESL-G3 models high capacity(High Density Expansion Modules), 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.