Backup Tape Buyers Guide
What is a tape backup drive for?
For business or public sector organisations, backup, backing-up or archiving are the common terms used when referring to data that is no longer accessed on a regular basic but must be kept long-term due to commercial, compliance or regulatory reasons. Although many businesses may choose to backup live versions of their data by mirroring to off-site storage systems - either on-premise at other locations or in the public cloud, this practice is separate to the backing up of older data.
Backing-up data using HDDs and SSDs or cloud storage isn’t practical as the cost quickly spirals out of control. In addition, even the best server HDDs and SSDs only have six year warranty. In contrast, despite its slow performance, tape remains the best format for backup as it offers much lower cost per terabyte and most tapes are typically rated for up to 30 years.
In this guide we’ll look at the common types of tape technology available today and why you should consider them, so you are sure to make the best decisions when choosing a back-up or archiving solution.
What is a tape drive?
Tape storage works by way of two components - a tape drive that writes and reads information, and a magnetic tape that has the data written to it or read from it. Rather than an alternative to HDDs and SSDs technologies is it used to compliment them, providing a very specific function - backup and archiving. Tape technology usually sits at the edge of the core network connected to the HDD and SSD storage systems so that a duplicate copy of them can be made for long-term storage.
Tape is a much older technology and works differently to HDDs and SSDs in that it must be sequentially written and read - meaning you can only write to blank sections that follow already written sections and you can only read one section by reading the others before it - later generations use LTFS (Linear Tape File System) to improve access - more on that later.
Although magnetic tape media may seem old and clunky next to HDDs, SSDs and the cloud, it does have numerous advantages that make it ideal for back. Firstly, once data is written to the tape it is usually removed from the drive making it un-hackable. Even archive HDD and SSD systems, whether on-premise or in the cloud need to be connected to a network so they vulnerable. Secondly, tapes are much cheaper than cloud storage SSDs and in many cases HDDs, so prove very cost-effective for keeping a copy of critical data with minimal overhead cost and risk.
Backup tape formats
Although all tape solutions use magnets tape to record the data, much like in most areas of technology there was no one standard tape format, with the options including DDS (Digital Data Storage), AIT (Advanced Intelligent Tape) and SDLT (Super Digital Linear Tape). Over the years each of these standards had multiple generations to provide additional capacity, however only a single type remains widely in use today - LTO or Linear Tape Open, often called by the brand name Ultrium.
LTO or Ultrium technology was first invented in 2000 and has since progressed through nine generations as of 2023, with a further five in the pipeline - it is supported by major storage brands including HPE, IBM and Quantum. These generations mainly differ in the capacities of an individual tape. The original LTO-1 versions had a capacity of 100GB uncompressed or 200GB compressed, and the latest versions 18TB and 45TB respectively. Compression offers the ability to fit more data onto a tape at a ratio of either 2:1 or 2.5:1 theoretically, but the ratio will differ with the type of data being written. The below table summarises the various LTO generations.
| Format | Year Released | Native Capacity | COMPRESSED CAPACITY |
Max Speed (Native) |
Max Speed (Compressed) |
|---|---|---|---|---|---|
| LTO-1 | 2000 | 100GB | 200GB | 20MB/sec | 40MB/sec |
| LTO-2 | 2003 | 200GB | 400GB | 40MB/sec | 80MB/sec |
| LTO-3 | 2005 | 400GB | 800GB | 80MB/sec | 160MB/sec |
| LTO-4 | 2007 | 800GB | 1.6TB | 120MB/sec | 240MB/sec |
| LTO-5 | 2010 | 1.5TB | 3TB | 140MB/sec | 280MB/sec |
| LTO-6 | 2012 | 2.5TB | 6.25TB | 160MB/sec | 400MB/sec |
| LTO-7 | 2015 | 6TB | 15TB | 300MB/sec | 750MB/sec |
| LTO-8 | 2017 | 12TB | 30TB | 360MB/sec | 900MB/sec |
| LTO-9 | 2021 | 18TB | 45TB | 400MB/sec | 1.0GB/sec |
| LTO-10 | TBC | 36TB | 90TB | 1.1GB/sec | 2.7GB/sec |
| LTO-11 | TBC | 72TB | 180TB | TBC | TBC |
| LTO-12 | TBC | 144TB | 360TB | TBC | TBC |
| LTO-13 | TBC | 288TB | 720TB | TBC | TBC |
| LTO-14 | TBC | 576TB | 1.44PB | TBC | TBC |
As with most technology, it is clear to see that with each generation the capacity increases and the speeds increase too. However, it must be pointed out that backwards compatibility is not a given. A general rule is that any generation of tape drive is compatible with the two previous tape generations, but not the ones prior to this - for example an LTO-9 drive will read and write to tapes from LT-9, LTO-8 and LTO-7 standards but not from LTO-6 or earlier. This means that if you have standardised on an LTO generation you either need to keep an older drive to read the older tapes or upgrade your whole archive. For this reason, older tapes right back to the original LTO-1 versions are still available to buy, and the drives are usually not superseded instantly by the new generation either. It is also worth mentioning that it is still possible to get tapes from the defunct DDS, AIT and SDLT standards too, as much like LTO there will be significant install bases out there.
Tape drives & libraries
We’ve mentioned that the tape drive is what actually writes and read the data on the tapes, however there are several types of drive available including 5.25in internal drives, external drives and drives integrated into standard 19in rackmount chassis. All of these drive types have a single or dual tape slot where the tapes must be manually loaded and removed for each tape used. Connectivity is usually in the form of SAS 6 or 12Gb/sec interface regardless of whether the drive is standalone or rack mounted.
Internal / External LTO Tape Drive
Rackmount LTO Dual Tape Drive
Another type is a tape library - this is where the unit is larger and usually rackmounted containing either a single or dual tape drives but also multiple slots for tapes. This allows for automation and scheduling as the library appliance can change tapes from the drive(s) without any human involvement - much more useful when considering the archiving of large amounts of data from business or organisation. Tape libraries scale from 8 or 16-slots at the entry level up to over 10,000 slots at the top end - delivering many hundreds of petabytes of backup capacity.
Single Drive LTO 16-slot Tape Library
Scalable High Density LTO Tape Library
Libraries with a greater number of slots allow for many weeks or months’ worth of operation without needing to do anything, as tape capacities are often chosen to allow one tape per day to make a backup of new data. Once each tape in the library has been used the whole batch can be replaced and moved offsite for secure storage.
Tape drive features
Aside from compatibility, capacity and speed differences there are also several features that have evolved over the numerous versions - these offer additional efficiency and security.
The Linear Tape File System (LTFS) makes it easy to quickly and precisely locate and retrieve any item of data stored on an LTO Ultrium cartridge. Standard from LTO-5 onwards, it allows a portion of the tape to be partitioned for indexing, which tells the drive precisely where in the tape a file is stored. Another partition holds the actual file making it to search and retrieving data.
LTO Ultrium tape technology has the ability to encrypt data without having to invest in software or separate devices. The data is scrambled to make it unreadable until or unless it is unlocked using a key code by the intended recipient. As well as protecting data confidentiality whilet tapes are in transit, encryption also provides a reliable way to confirm a person’s authority to see the information.
Industry regulations, along with internal and industry policies, impose strict disciplines about how data should be stored, and for how long. Failure to comply can result in legal penalties, so LTO-3 and onwards supports a write-once, read-many (WORM) option that stores data in a non-rewritable format. This means that data cannot be tampered with as when a WORM data cartridge is inserted into an LTO drive, the drive will recognise it and will not allow any data on the tape to be overwritten.
Choose your backup solution
Hopefully you’ve found this guide useful in providing a complete picture as to the considerations and decisions that should go into choosing a tape backup solution for your organisation. Click below to see our range of products available.