In This Article
What is Tape Drive?
A tape drive refers to a removable data storage device. It is designed with a magnetic tape in it that reads, writes and stores data.
- A tape drive typically reads and writes data and information on a magnetic tape.
- Magnetic tape data storage can be used offline typically as archival data storage.
- A tape drive usually has a long archival stability and a positive unit cost.
- Since a tape drive offers sequential access storage which a hard disk drive does not, it offers direct access storage.
Understanding Tape Drive
The tape drive storage can be successfully used as a medium to archive data and it is perhaps the best solution for efficient long term storage.
The first computer to use a tape drive for storing data is UNIVAC or the Universal Automatic Computer.
The components of the tape storage system may vary and it depends on several different factors.
However, in general, a tape storage system comprises three basic components such as:
- A magnetic tape medium
- Tape drive and
- Tape automation.
As for the reading and writing of data on the tape storage system, it needs software to control these operations.
The narrow magnetic strip on one side of the tape stores data by going under the magnetic head and the data in it is typically stored in bits.
The magnetic strip can store different types of data and digital information.
Usually, a tape drive is used commonly in cassettes and cartridges and the tape records audio or visual data as well as software.
However, unlike the disk drive, the tape drives usually have a high average access time because it has to wind the tape physically between the reels in order to read a particular piece of data.
It cannot move to any place in a few milliseconds like in a disk.
Still, a tape drive can stream off the data pretty fast when the desired position is reached.
For example, the LTO or Linear Tape Open can support data transfer rates of up to 360 MB/s which is not bad at all as compared to the data transfer rate of the hard disk drives.
The tape drives evolved over time significantly since it was first launched in the early 1950s.
It is due to the evolution in data processing at the enterprise level that has forced the magnetic tape to go through several iterations over the years in order to enhance the speed of accessing the stored data as well as the storage capacity.
In the 1970s, these drives were mounted manually and the tape needed to be threaded through its drive components.
However, today, these drives are more compact in design and can connect easily and directly to several devices such as:
- The computers
- The storage area networks and other systems.
Though the big reel-to-reel tape drives that you saw in the movies of 1950s and 1960s are still used, it is used mainly for archival storage in the long term.
Otherwise, today, more advanced approaches are followed to increase the data transfer rate and storage capacity to several hundred megabytes per second to terabytes, respectively.
There are a few specific advantages of storing data on tape. One of the most significant advantages is that it offers a high capacity of storage.
Apart from that, storing data on tape is also a less expensive option that offers both archival storage and backup storage solutions.
These storage devices are also very easy to store due to their compact design.
Some other benefits of using tape storage are:
- Its high life span provided it is stored is a suitable environment
- Its transportability which allows it to be moved from one place to another and use as offline storage and
- Its security since modern tape drives support data encryption features such as Advanced Encryption Standard 256 along with a range of other data protection features at varying levels.
The tape drives create an air gap between the systems that are vulnerable to cyber risks.
Simply remove the tape cassette from the drive and you can protect your data backup and ensure disaster recovery.
However, there are some downsides of using a tape drive.
These drives typically follow a sequential storage and access approach to read and write data which takes time to reach to the particular data.
Moreover, the tape drives spin very fast. Therefore, start, stop and backup action cycles are required to reach the exact point of the data.
This not only adds to the time taken to access the data but also results in excessive shoe-shining which results in slowing down of the response time of the drive.
It also causes faster wearing out of the drive and tape, thereby reducing the lifespan of both in the process.
Also, the overall efficiency of processing by the drive is cut short by the start-stop operation.
Data stored on tape is accumulated typically in the buffers before it is streamed onto the tape.
If this buffer is not full then the tape may stop and position itself for the following data delivery from the buffers.
The data in a tape drive is stored on a magnetic tape by recording it on a loop of celluloid-like and flexible material.
The data stored on it can be read and can be erased as well.
The tape drives usually work by using a conventional helical scan. In this specific technology the head touches the tape while recording or playing back.
It may also follow linear tape technology. In this process the head does not touch the tape.
The drives used in the process can be of two particular types such as:
- Rewinding and
In rewinding drives a rewind command is issued at the session end and is usually used when the tape needs to be dismounted in the end of processing huge amounts of data in batches.
On the other hand, non-rewinding drives are typically used for incremental tape backups and other similar applications where at the end of the prior session a new file is added.
The tape drives may come in different capabilities and sizes.
Some may be standalone units while others may be stacked in the racks of a data center creating a tape library.
Moreover, the tapes themselves may be located inside a sealed cassette which you can insert into a drive and activate.
Formats in Use
The tape formats used may vary according to the technology used. For example, in the linear tape drives, Linear Tape Open, which is also known as LTO Ultrium, is the primary format used.
This format was developed jointly by International Business Machines or IBM, Hewlett Packard or HP and Quantum as a component of the LTO Consortium.
This open standard can be licensed by any tape drive manufacturer.
Though the helical scan drives still exist, the linear tape drives are used extensively because it is better in cost, performance and convenience.
The Linear tape File System allows the users to see and access the tape files along with the LTO specification just like the disk-based media files.
The LTO separates the tape with the actual data and a content index.
This particular arrangement expedites the read/write speed and the potential of the linear tape systems.
What is It Used for?
The tape storage, as you know, may have several uses where its primary objective is to store, read and write data on the magnetic tape such as:.
- Cassette tapes are the most common use cases and were used in homes as well as in other places as well in the 20th century.
- Another common household item that used tapes is the Video Home System or VHS tapes that stored visual data and movies.
- Tape storage is extensively and preferably used for long term storage as a low cost option, according to the Tape Storage Council.
- LTO or Linear Tape Open is also used extensively by the film industry since it gives them a large capacity to store huge volumes of visual data.
- Since the tape storage is less likely to fail and more scalable, these are used for secondary or tertiary applications and offsite backup of data.
A tape drive is also used to store data and create a backup for the information from a computer. It can be used to create backup for different things in this case such as:
- Individual files and folders
- The whole drives and even
- The contents of the whole computer system.
Most importantly, a tape drive is used to restore any lost or damaged data with the help of the software.
How is Data Stored on Tape?
There is iron oxide coating on one side of the tape. Sometimes this narrow strip can be coated with a material that can be easily magnetized such as magnetic oxide.
When the tape records the data, the electrical signals passed onto it creates an imprint on the tape.
There is a recording head through which the tape goes to reach the imprint on the tape.
The tape then passes through the reproducing or playback head. It produces a signal which then creates a recorded signal which thereby increases the intensity so that it can align with the output device.
The magnetic oxide is magnetized by the magnets and this magnetized oxide retains the magnetization which stays until it is forced to change by going through another magnetic reading.
As you may know data is read or written by the computers in a set of binary numbers comprising 1 and 0.
This is typically a machine language. The magnetic tape stores this data using the North Pole and the South Pole at the two ends.
Directs are used to embody the data in the binary code and for that it first breaks the data down into bits.
This bit size memory is stored in the blocks present in the tape. Once again, the data in these blocks are represented either in the North Pole or the South Pole at the two ends.
Since the tape passes below the electromagnetic head which is aligned perfectly with the space allotted to store data in bits.
This magnetic head instructs the magnetic field towards this space and when it passes the bits start turning either up or down.
It all depends on the information of the magnetic field received by the magnetic head so that the location of the bits is revised.
The read head is then used to read the data. This head is located at the tip of the actuator arm.
When the tape is magnetized, seven or nine bits are recorded in parallel along the tape width and while reading or writing the bits the head does it in parallel.
There are gaps in between the records on the magnetic tape to separate them.
This helps in proper synchronization and avoiding overlapping or collision of data.
These records create simple sets and these are called files that have a file mark in the beginning that helps in locating it easily.
An identifier or a header is used to identify a file depending on the search commands given by the users.
The read and write heads in the tape drives are fixed and it moves at a linear velocity to the head.
When a record is to be read the head then goes through all the prior sets to reach the specific record.
Ideally, there are two specific methods followed for recording on tape storage namely linear and scanning methods.
In the linear method, the data is stored in parallel tracks which help in spanning it throughout the length of the tape.
Several tape heads are used at the same time to write parallel tracks on a medium track.
This method is quite old and used typically in the older tape versions but is quite a simple way of recording. However, it has a low data density.
Today, in the linear recording technology, a linear serpentine version is used which helps in tracking several tape heads at the same time but each head can write only a single track at a time.
In the old version the data was written on the tape in parallel sides at the same time but in the modern version of the linear recording technology, data is written first on one line and then it is written in a parallel line.
When the second set of tracks is written, the head shifts slightly and passes to the opposite direction.
It stops when all the tracks are read or written. In this new method, the tape can have more tracks as compared to the reading/writing process by the older technology on a tape of the same length and number of heads.
Therefore, the newer linear serpentine method boosts the capability of data storage on tape.
In this recording method, the data is not recorded along the length of the tape. Instead, shorter and denser tracks are written along the width of the tape.
During the scanning process, the disk runs at a high speed but the tape moves relatively slowly.
This method actually offers a much higher data rate in comparison to the linear method.
In this method while reading data from or writing data to the tape, the tape head with the spinning disk is located perpendicular to the tape and the outer edge of it. This is called the traverse method.
Accurate scan was used before this transverse method in which the read or write head is located on the top of the flat spinning disk.
Since this disk is flat with respect to the tape, it forms an arc and the data is recorded in a diagonal manner by using the helical scan.
This helical scan records the tracks in shorter and denser form.
This method is extensively followed now to record data in the prevailing videotapes systems as well as other data tape formats.
How Fast are Tape Drives?
Typically, the tape drives are not as fast as the Solid State Drives or SSDs or the Hard Disk Drives or the HDDs.
It certainly lags in the data accessing and retrieval speeds.
It is due to the linear nature of the tape drives that is its strength, in terms of storage capacity, as well as its weakness, in terms of data accessing speed.
If you consider the uncompressed tapes, the read speed could be up to 400 MB/s.
This is far better and higher than the LTO tapes of the first generation which offers a maximum speed of up to just 20 MB/s for the uncompressed versions and just double than that for the compressed tapes.
And, if you consider the mid-range and current enterprise tape drives, the data transfer and accessing speed may range anywhere between 100 MB/s and 150 MB/s.
Still, the speed of the tape drives is much slower in comparison to the data transfer and accessing speed of the disk drives and flash drives.
How Long Can Tape Drive Last?
According to the statements and claims of the tape manufacturers usually a tape drive will last for about 30 years.
However, this lifespan is not written on stone and may vary according to the features of the drive itself.
For example, the LTO tapes are very sensitive as a storage solution and the life expectancy will largely depend on the conditions and usage.
If you want it to last for 30 years, the storage conditions should be ideal such as:
- A constant relative humidity of about 40% and
- Preferably a constant temperature of around 70 degrees Fahrenheit.
The lifespan of the tape can reduce significantly even if there is a slight variance in the storage and usage conditions.
Higher or lower temperatures even by 5 degrees, higher humidity, and even exposure to higher level of lights can have a negative effect on the life of the tape drive, deteriorating it more quickly.
However, evaluating the life expectancy of an LTO tape, which is more commonly used, is quite critical. It can be measured in different ways such as:
- In number of passes or
- In a number of years.
In addition to that, there are also several other aspects and factors to consider and all of it is explained hereunder.
First, you will have to consider the generation of the LTO tape because depending on that factor the life expectancy will vary.
Typically, there are five generations of this tape available through LTO 1 and LTO 5.
If you evaluate the life expectancy of a tape drive based on the number of passes, you will need to consider the number of times it can safely pass over the read and write heads before the conditions start to deteriorate.
However, depending on the specific type of tapes, such as the LTO tapes, calculating the lifespan depending on the number of passes solely can be quite misleading.
This is primarily because these tapes use the serpentine recording path.
For example, the LTO 2 and LTO 3 variants can pass over the head 64 times for reading a complete cartridge.
This means that if a tape is supposed to make a million passes, which is considered to be the standard for LTO tapes, it can make only 15,625 complete reads safely.
Also, the dust trapped in the tape drive can reduce both the number of safe passes as well as the life of it.
So, it is needed to make sure that the tape is dust free by closing the shutter when it is not in use.
However, the tape drives are not going anywhere soon due to several good reasons such as:
- Its lifespan ranging anywhere between 15 and 30 years which is much, much higher in comparison to hard disk storage which has an average life expectancy of about 5 years
- The open format or open standard of the Linear Tape Open which is more resilient
- Its success rate and the roadmap which promises higher efficiency and longevity
- Its low error rate as opposed to any other form of digital storage media that are known to be pretty prone to errors
- Its security as a medium for archival storage and its removability that makes it both safe and portable
- The high storage capacity offered which can be as high as 12 TB or more in the current generation that allows storing as many as 1600 HD movies in each cartridge and
- Its cost effectiveness though the cost per gigabyte may drop when you store more data.
However, to end, it can be said that you can use a tape drive successfully for your storage needs if you are a bit careful about its use and maintain it properly with the help of experts.
Also, make sure that you have efficient people to manage the hardware, software, media and the tape drives and libraries.
Since these drives are very energy efficient in comparison to the disk drives, you will not need them to keep powered up.
It will need only a little bit of care and a little investment to give it a proper working environment such as an air-conditioned room and proper moisture control.
The tape drive is a useful component that provides a productive and effective storage solution to the computer users.
Going through this article now you surely are well aware of its usefulness and working process.
If you are not already, you can choose to use it, now that you know that it will last for years.