Tape storage is a data storage technology that uses magnetic tape data storage media to store and retrieve data. Tape storage technologies include open reels, cassettes, and cartridges that house reels of tape inside a plastic enclosure.
Tape storage dates back to the 1950s, when IBM introduced the 726 tape system which recorded data on open reels of tape up to 10.5 inches in diameter. In the 1960s and 1970s, automated tape libraries were developed to manage large tape collections. In the 1980s, cassettes and cartridges became the predominant tape media due to their portability and durability.
Tape storage works by writing data to tracks on a magnetically coated strip of plastic film or Mylar tape using a tape drive. The drive passes the tape over a stationary recording/reading head. Tape drives use either helical scan heads that move at an angle to the direction of tape movement or linear heads aligned perpendicular to the tape movement. Multiple tracks allow for very high data densities on tape.
Tape is a sequential storage medium, meaning data is stored and read back linearly from start to end. Tape has historically offered a more cost-effective solution for long-term data retention compared to disk storage. Today, tape is ideal for data backup, archiving, and cold storage applications.
Sources:
https://medium.com/@mediaduplicationsystem23/the-evolution-of-tape-storage-how-modern-tape-drives-revolutionize-data-backup-b64ffb862bc5
https://share.confex.com/share/124/webprogram/Handout/Session16709/Tape%20is%20Dead_Really.pdf
Types of Tape Storage
There are several common tape storage formats used today, each with their own characteristics and use cases:
Linear Tape-Open (LTO) is one of the most popular tape formats used for backup and archiving. LTO tapes are available in different generations, with each generation offering increased capacity. Current LTO generations include LTO-8, LTO-7, and LTO-6. LTO cartridges can store up to 12 TB (uncompressed) per tape.
Digital Linear Tape (DLT) is an older tape technology that was traditionally used for enterprise backup. DLT provided high capacity tapes but has been largely replaced by LTO. Some of the DLT formats included DLT IV, DLT-S4, SDLT, and VXA.
Oracle T10000 and IBM 3592 are enterprise-class tape formats optimized for high-capacity storage. The T10000 T2 cartridges can store up to 8.5 TB per tape while the 3592 cartridges can store up to 10 TB per tape.
Quantum’s SLR tape format offers very high capacities with low costs per TB. However, SLR drives are not compatible with other common tape formats.https://www.devx.com/terms/backup-to-tape/
Benefits of Tape Storage
Tape storage offers several key benefits that make it an attractive option for certain use cases:
Durability – Tape cartridges are very durable and can withstand dust, debris, and temperature fluctuations much better than other media like hard drives. Tapes stored properly can last 30 years or more (Source).
Portability – Tape cartridges are small, light, and portable. They can easily be transported offsite for disaster recovery purposes or long-term archiving (Source).
Longevity – The expected shelf life for tape is 10-30 years or more if stored properly. Compare this to 3-5 years for consumer hard drives (Source).
Low Cost – The cost per GB is much lower for tape storage compared to primary disk storage. This makes it very economical for large amounts of infrequently accessed data (Source).
Drawbacks of Tape Storage
Despite the benefits, tape storage also has some disadvantages compared to other storage mediums like hard disk drives (HDDs) and solid state drives (SSDs). Some of the main drawbacks of tape storage include:
Slower access times – Retrieving data from tape is a sequential process, so it takes longer to locate and access data compared to disk storage which provides random access. Tape drives need to locate the correct tape, spool to the correct position, then read the data. This results in access times ranging from seconds to minutes for tape, compared to milliseconds for disk drives.
Capacity limits – The maximum native capacity of tape cartridges is currently around 30TB for the latest LTO-9 format, whereas disk drives can offer capacities in excess of 100TB per drive. While automated tape libraries hold multiple cartridges to provide larger overall capacity, the single cartridge capacity is still limited compared to some disk storage systems. However, tape drives use compression which can effectively double capacity.
Compression considerations – The high compression ratios touted for tape drives are beneficial for maximizing capacity, but they come with performance tradeoffs. Compression and decompression add to the data access latency. Also, some data may not compress well, reducing the realizable capacity gain. Large databases and other pre-compressed data may see minimal capacity boost from tape compression.
Sources:
Use Cases for Tape Storage
Tape storage is commonly used for backup, archiving, and long-term data retention. Its portability, capacity, and low cost make it well-suited for these use cases:
Backup: Tape is a popular medium for backup and disaster recovery. Tapes can be easily transported offsite for protection against events like fires or floods. The linear format makes restores from backup tapes relatively quick and simple. Tape’s high capacity allows storing many backups on a single cartridge.
Archiving: Organizations use tape for archiving data that must be retained for regulatory compliance or business reasons, but is not frequently accessed. This could include financial records, medical images, seismic data, and more. Tape archives are energy efficient and the media has a long shelf life.
Data retention: Tape excels at retaining data for many years. LTO tape cartridges can preserve data for 30 years or longer if properly stored. The media does not degrade like other forms of storage. Tape retention meets needs for regulatory compliance and corporate policies.
Sources:
https://www.enterprisestorageforum.com/hardware/tape-storage-market/
https://www.nextplatform.com/2020/12/17/big-blue-shines-a-light-on-the-future-of-tape-storage/
Tape Storage Capacity
Tape storage has seen incredible growth in capacity over the years. Early tape drives in the 1950s and 1960s had capacities in the megabytes or tens of megabytes. For example, the IBM 2400 series tape drives introduced in 1964 had a capacity of 7.5MB 1. Fast forward to today, and modern LTO (Linear Tape-Open) tape drives now offer compressed capacities in the tens of terabytes.
The first LTO generation launched in 2000 offered 100GB native and 200GB compressed capacities. The latest released generation, LTO-9, provides 18TB native and 45TB compressed storage per tape cartridge 2. According to projections from the LTO roadmap, LTO-10 is planned for 2024/2025 with capacity targets of 48TB native and 120TB compressed. This represents a nearly 3x increase over LTO-9 capacities
.
The massive boost in tape storage capacity over the decades has been a key driver of tape’s continued use for data backup and archiving despite competition from disk and cloud storage. Tape’s incredibly low cost per terabyte stored ($0.017/GB for LTO-8) makes it an efficient long-term storage medium.
Tape Storage Speeds
One of the key performance factors for tape storage is the native transfer rate, which refers to the speed that data can be written to or read from the tape with no compression. This provides a baseline measurement of performance.
The latest generation of tape, LTO-9, has native transfer rates up to 400 MB/s for uncompressed data according to IBM 1. When data compression is used, transfer speeds can exceed 1000 MB/s. For comparison, the previous LTO-8 generation offered native speeds up to 300 MB/s and compressed speeds up to 750 MB/s.
Other factors that affect tape performance include the drive technology, the controller, and the connection interface. Faster SAS, Fibre Channel, or PCIe interfaces enable higher transfer rates compared to older SCSI connections. The drive’s caching algorithms also impact how efficiently data is written to the tape.
Overall, modern tape drives provide very fast throughput comparable to many hard drive technologies. This makes tape suitable for large volume backups and archives when high capacity and bandwidth are required.
Managing a Tape Library
Modern tape libraries are highly automated and contain robotics to manage a large number of tape cartridges. According to Oracle, “A tape library contains tape drives, slots to hold tape cartridges, a barcode reader to identify cartridges, and a robotic picker to move cartridges between slots and drives.”
The key components in managing an automated tape library include media management and cataloging. Media management refers to activities such as adding and removing tapes from the library, monitoring media health, and recycling tapes. According to IBM, careful media rotation is crucial to evenly distribute wear on tapes.
Cataloging is the process of tracking what data is stored on each tape. Sophisticated software tracks detailed metadata about each tape cartridge and file stored in the library. This allows the system to quickly locate the correct tape when data needs to be retrieved. Proper cataloging is essential for efficiently utilizing a tape library.
New Innovations
The LTO (Linear Tape-Open) roadmap shows continued innovation in tape storage capacity and speeds. LTO-9 was released in 2020 with a native capacity of 18 TB and compressed capacity of 45 TB, doubling the capacity of the previous LTO-8 generation [1]. LTO-10 is under development with an expected native capacity of 36 TB. The LTO roadmap envisions capacities reaching 120 TB compressed in future generations through 2030 and beyond [2].
In addition to higher capacities, new innovations focus on increasing tape speeds and reliability. For example, Fujifilm and IBM recently announced a new prototype drive and medium that can achieve over 525 MB/sec transfer rates, which is faster than previous LTO generations [2]. Other companies are developing new servo and head technologies to boost performance.
Besides LTO, alternatives like Sony’s Optical Disc Archive and Oracle’s T10000D offer different capacities and formats. Overall, continuous tape storage advances ensure it remains a viable option for long-term data retention and archiving.
The Future of Tape Storage
Despite the emergence of flash memory and cloud storage, tape continues to play an important role in data center storage strategies. Tape offers unmatched reliability and cost efficiency for long-term data retention
(Why the Future of Data Storage is (Still) Magnetic Tape). For example, estimates suggest a tape cartridge stored properly can last up to 30 years, far longer than any other digital storage medium.
While disk and flash offer faster access times, tape provides much lower cost per terabyte stored. Tape is ideal for rarely accessed “cold” data that needs to be retained. The low cost and high density make tape well-suited for bulk archives (Big Blue Shines A Light On The Future Of Tape Storage).
Cloud storage is emerging as an alternative for data archiving. But tape is more cost-efficient for long term retention of massive data volumes. Tape also provides air-gapped data protection, reducing security risks. With continued improvements in capacity and access speeds, tape will continue playing a key role despite the rise of other storage technologies.
