Tape is the IT industry’s longest-lived magnetic medium and offers a number of benefits over spinning disk and flash technology.
These include capacity and cost. Once a tape system is set up, it is cheap to run and easy to expand. Tape also now works directly with file systems, making it almost as easy to use as NAS.
Tape is a very robust medium – industry advocates say it is more reliable than spinning disks.
But tape remains slow, and although capacities are increasing, even a 100TB tape archive will require manual processes or a mechanical tape library. And businesses need robust backup and archiving processes to make the most of tape’s advantages.
Benefits, limitations and developments of tape
A single LTO-8 tape holds up to 12TB of data natively, with up to 30TB after compression. This is expected to rise to 48TB with LTO-10 and potentially, 192TB with LTO-12. And, as a removable media, there is no upper capacity limit on a tape system – IT teams can just add more cartridges.
Although LTO tape systems are fairly expensive to buy – ranging from around $3,000 for a simple desktop unit to $5,000 and upwards for a rack-mount system – tapes themselves are cheap. Older-generation LTO-7 tapes cost £60-70 with 12TB LTO-8 tapes costing £90-100.
The low cost of tape cartridges makes it an economical long-term storage medium, and allows organisations to make multiple copies of their backups.
But the initial outlay is only part of the cost. The lifetime cost of tape is very low. Unlike a drive, an archived tape needs no power. And as long as tapes are stored correctly, they will not wear or deteriorate over time.
As analysts at the Enterprise Strategy Group point out, higher-capacity tapes – with more data held on fewer cartridges – simplify workflows for larger datasets, further cutting operating costs.
Another advantage of tape is that its areal density will allow for many more increases in storage density. Tape systems pack less data on the medium’s surface area than disk.
That means, according to industry body Ultrium LTO, that tape stores around one-tenth of the data per square inch that disk does. This allows tape manufacturers to continue to increase storage capacity, without changing the physical dimensions of the drive or cartridge.
Tape is also becoming faster. LTO-8 tapes can manage 360MBps data rates, or 750MBps compressed. That is fast enough for systems such as business intelligence or analytics to read archived data from tape, as well as to cut backup and recovery times.
Tape is also more flexible than it used to be. It can now provide the medium for file system-like operation, via LTFS.
Previous generations of tape systems used their own file formats and only worked with proprietary backup software, says Tony Lock at analysts Freeform Dynamics. “Before LTO, you had to recover from the existing format,” he says. “Now you don’t have to rely on old backup software.”
Use of file systems also makes it easier to integrate tape into tiered storage with disk arrays and flash.
The other main downsides of tape remain the reliance on manual or mechanical workflows, including potentially long restore times that still lag behind those of drives, and the need to manage the media carefully.
Whether these are deal-breakers will depend on how an organisation uses tape.
“You must have a very good plan for deploying a tape environment,” says Patrick Dekkers, storage specialist at Amsterdam’s University Medical Centre. “Not all data can be placed on tape. Sometimes it takes a bit more time to get data from tape instead of disks. It works best for large files that need long-term storage.”
Top five use cases for tape
1 Backup and recovery
Backup is the traditional use case for tape, predating newer formats such as LTO and LTFS. Although LTFS removes the need to use dedicated software to read tapes, backup and recovery applications are increasingly media-agnostic. This allows organisations to combine snapshots to disk with longer-term backups to tape, and also the cloud.
According to Freeform’s Lock, one advantage of tape is that it is easy to make copies. Software can write to two or more tape drives at once, allowing for a local copy and a copy for off-site storage.
2 Long-term archive
Tape works well as a data-archiving medium because of its low operating cost and reliability. With organisations capturing more data for analytics and storing historic records on disk, storage quickly becomes expensive. Tape archiving is also popular in R&D and the media and entertainment industries for storing large files.
Better data management software is also making it easier to archive to tape. IBM’s Spectrum Archive, for example, uses LTFS so that it can write data to drives or tape without additional management tools.
3 Warm archives
Faster tape systems are allowing IT teams to use tape for near-line storage or “warm” archiving for records and data. The use of tape libraries or “jukebox” subsystems, along with larger capacity tapes, have gone some way to closing the performance gap between tape and disk.
Technologies such as FLAPE – flash plus tape – should improve performance further, and suppliers such as Quantum and Spectra Logic are combining tape, disk and cloud to optimise cost and performance.
4 WORM and compliance
Long-term data retention for compliance and regulatory reasons is a growing issue for business. Tape works well in this scenario, as it can create an immutable data record. IT teams make tapes write once read many (WORM) and store them on-site, off-site, or both.
Although restoring data from tape is slower than from other media, it is low-cost. Restoring data from public cloud infrastructure typically involves data egress fees. Organisations need robust archiving systems to ensure their tape archives are compliant.
5 Security and ‘air gapping’
The use case for tape that has gained the most attention in recent months is security. To counter ransomware and ransomware-DOS (denial of service) attacks – where the victim is denied access to their data – having effective backups is critical.
The advantage of tape is that it can be stored offline, completely separated (air gapped) from the parent IT system. This allows organisations to recover their data, even when ransomware has taken out their networks.
For this to work, though, both security and off-site backup procedures must be robust. There is no point in storing incomplete data, or backing up malware.
“The challenge is making sure the information you are backing up is clean in the first place,” warns Lock. “A lot of ransomware is inactive for a long time before it is detected.”