Is Tape Still a Viable Option for Backup?
Historically tape has been the most used storage medium for the backup and recovery of primary data. IT professionals have used tape for archival purposes since the 1950s. Tape has been used for such a variety of storage functions, in organizations of all sizes that it has almost become a fixture in today’s networks.
Despite continued advances in data-transfer speeds, disk buffers, robotics, storage capacity and other features, when it comes to storing and accessing data, tape cannot compare to the speed, efficiency and reliability of hard disks. Then why has tape become such a widespread storage medium when tape’s performance, scalability or reliability are questionable at best? The two main reasons IT professionals have stayed with tape are cost and portability.
Nevertheless, when exploring some of the characteristics of tape, it is simple to understand why it is not the perfect media for data backups and why it tends to be such an uncooperative medium.
Tape often is touted as the media for long-term retention, but that is not really the case. To accommodate a high volume of data, modern tape cartridges such as Linear Tape-Open (LTO) have 846 meters, or approximately one-half mile length of tape. That enormous length of tape is then fitted inside a four-inch cartridge. To accomplish this, the tape has to be extremely thin, just 6.6 micrometers or 6.6 millionths of a meter. A single strand of human hair is more than 10.6 times thicker than the thickest tape.
The majority of the tape’s 6.6-micrometer thickness is made up of a plastic base. The base supports the all-important magnetic layer. The magnetic layer is where data is retained and it is literally 100 nanometers thick, in the case of an LTO tape. The tininess of a nanometer is so difficult to comprehend. On a comparative scale, if the diameter of a marble was one nanometer, then diameter of the Earth would be about one meter.
Also microscopically thin, are the tracks for recording data. The half-inch width of an LTO-6 tape has 2,176 parallel tracks, each of which is micrometers in width. Reading all of the data stored on the microscopic tracks relies on the exacting accuracy of the servo tracks, which are applied to the tape at the manufacturing level and the proper alignment of the read head with the recorded track.
Because the tracks are so thin and everything so small, even microscopic particles can interfere when reading data. Contaminants such as dust, fingerprint residue, and even material shed from the tape itself can cause dramatic effects. Physical degradation and increasing error rates are a direct result of the fragility of tape and contribute to the practical implications for long-term storage.
Writing a complete LTO-6 cartridge requires 136 passes through the drive. Each pass exposes the tape to contact with guide rollers in addition to the read/write head.
Over time, the chemical stability of the binders that hold the magnetic layer together can become degraded. Humidity and temperature variation can cause the tape to stretch or shrink, degrading the critical spacing of the servo tracks. This can cause the read heads to slip off the recorded data track.
Although keeping a tape drive clean is important, normal cleaning cartridges are abrasive and frequent use will shorten the drive’s lifespan.
All these factors contribute towards the questionable reliability of tape.
Tape drives access data sequentially. That is, the drive must move the tape forward or backward until it reaches its destination. Shoe shining or backhitching is another reason why tape drives cannot perform optimally. This action takes place if data flow to the tape drive is not fast enough. The drive will stop and rewind to the place of the last write. This not only adds wear and tear to the tape, but also slows down the backup.
4. Backward Compatibility
Current tape drives will read/write one generation back and will read-only 2 generations back. So, if you have old archived data, you will need to migrate it to a newer generation media before it can be read.
5. Shamelessly promoting our product
Idealstor changed the need for tape dependence with the introduction of reduced-cost removable SATA-based secondary disk-storage products. This dramatically alters the way businesses deploy mission-critical backup and archival environments. Specifically, removable low-cost disk storage solutions are allowing enterprises to integrate disk-to-disk backups into their data-protection systems that have relied solely on tape.
Deploying removable SATA-based secondary disk storage in a data-protection solution can resolve a variety of issues confronting backup administrators. These include shrinking backup windows, demanding restore time requirements, and the need to purchase additional tape drives or a new tape library.