Tape nearline archives consist typically of a server which is network attached (NAS) and is running software that manages the movement of data from the primary RAID to the tape archive.
They meet the archive requirements as follows:
1) Lower cost than existing primary storage
- Yes, most companies have some form of tape backup already installed so only additional software required
- Tape has a low power consumption
2) Long term retention
- Yes, tape media life is estimated at 7-10 years
- However, tape technology is not always backwards compatible
For example a tape written with LTO1 technology cannot be read with the current LTO5 drive
3) Compliance with regulations
- No, tape can be altered as tape is fundamentally re-writable media
It requires additional software to prevent alternation of information
4) Transparent access to archival information
- Yes, but not suited for random access, tape needs to spool which results in:
— A lot of tape winding also reduces reliability
–Access to files is slow due to long delays in finding the start of individual files
5) Offline management of very old information
- Yes, removability of media allows for off-lining of information,
- However, tape needs periodic re-tensing to prevent tape adhering together
- Tape vulnerable to (electro) magnetic radiation
Tape systems have been used traditionally for making data back-ups and best suited for transferring large amounts of data in a single go. They are not designed for writing or reading individual files which is typical for an archive and this reduces their reliability. Tape is in most cases rewritable and as a consequence not applicable in many professional environments where regulatory WORM (write once, read many) archiving is required.
Compatibility is also an issue for tape users as every tape format is proprietary. As the tape standards change approximately every 7-10 years, this reduces extremely its efficiency as data has to be migrated to new standards and exchange between different suppliers could be complicated.