Big data storage demand is giving a new lease on life to a storage technology which only a few years ago was thought to be destined for the landfill: the magnetic tape.
First introduced on the Univac computer in 1951, tape is the oldest storage medium in use. While tape sales have been falling since 2008, this fall the trend has reversed showing a one per cent rise last quarter and an additional three per cent increase is expected this year by the Santa Clara Consulting Group.
Take for example the Large Hadron Collider (LHC) in Geneva which spews anywhere from three and six gigabytes of data every second. CERN (The European Organization for Nuclear Research), which runs the LHC, estimates the data it stores is doubling every three years and the need to store it in a reliable medium is critical.
Magnetic tape offers four key advantages over hard disks for long-term data storage, according to Alberto Pace, head of data and storage at CERN.
Speed – While it takes about 40 seconds for an archive robot to pick the right tape and install it in the tape reader, once the reel is installed extracting data from tape is about four times as fast as reading from a hard disk.
Reliability – When a terabyte hard disk fails, usually all the data in it is lost. By contrast, when a tape snaps, it can be spliced together again. Data loss if often limited to a few hundred megabytes each year out of CERN’s 100 petabyte tape repository. However, the organization loses a few hundred terabytes each year out of the 50 petabytes of data it stores in hard disks.
No power needed – Tapes do not need power to preserve the data it holds. By contrast, temporarily stopping a rotating disk by turning of the power increases the chances that it will fail.
Security – A hacker that manages to break into the CERN data centre could delete all 50 petabytes of hard disk data in minutes. To erase the same amount of data stored on tape would take years.
Keeping data in tape is cheaper than storing it in hard disk. Gigabyte of disk storage costs 10 cents as opposed to tape which is just four cents. Data in tapes can still be read reliably after three decades but data on disks is usually good for only five years.
Despite its advantages, tape is still not a silver bullet for data storage. But it serves a certain purpose.
“Hot data” or data that needs to be accessed immediately is best stored in flash memory, according to Evangelos Eleftheriou, manager of storage technologies at IBM’s research laboratory in Zurich.
Lukewarm data or data that people need to look into frequently but not immediately is more aptly store in hard disks.
Cold data which is being stored for the long term is best kept in magnetic tapes.
About 90 per cent of an organization’s data eventually falls into the cold data category after a couple of months.
Demand for tape storage continues to grow but current magnetic tapes hold only up to six terabytes of compressed data. That is why work on tape with higher densities continues.
But increasing tape densities in just half the battle. There is an even bigger challenge, according to Eleftheriou.