The storage lifetime of removable media - Backup/Restore

Computer Technology Review, August, 2003 by Mary Chesher

Data storage needs are increasing exponentially for most organizations. On top of that, new regulations such as HIPAA for the medical industry, Securities and Exchange (SEC) Act Rules 17a-3 & 4 for the financial services industry, the Sarbanes-Oxley Act for public corporations, and the Homeland Security Act are all requiring a great deal of long-term record retention for both large and small businesses, as well as government agencies.

Half-inch high capacity tape and optical media are the common removable media technologies used today to meet the growing data storage and record retention requirements. Tape has been a part of backup and storage solutions since its introduction in 1953. Optical media formats were breaking ground 20 years ago, and today users can choose from a wide array of CD and DVD formats to meet their storage requirements.

One of the more frequent questions that organizations have about their removable media is how long will it last, or what is its lifetime? The lifetime of removable media is defined as the length of time that the media can be successfully written to, stored and successfully read. The life expectancy for removable media can depend on many different factors including the quality of manufacturing, the care with which it has been handled, the conditions under which it has been stored, and how much it has been used. Another factor that has the potential of affecting the media lifetime is changes in technology. In this article, we will explore in-depth how each of these factors can affect the life of removable media.

Media Manufacturing

Manufacturers of removable media typically build their media under rigorous process controls to guarantee that product specifications are met for durability and archival stability. Environmental and stress testing are two measures taken to assure that the product will withstand the test of time.

Significant research has been performed to determine the lifetime and archival stability of magnetic media. The National Media Laboratory (NML), 3M and Carnegie-Mellon University have performed joint and independent studies to assess chemical, thermal and archival stability of advanced metal particulate coatings, and results projected that magnetic media may reasonably be expected to have a lifetime of 15 to 30 years under normal usage conditions. These conclusions are based on magnetic performance only and do not take into account other factors, like handling and environmental conditions, that may affect media lifetime and archival stability.

Handling and Care of Tape Cartridges

Together with the hardware manufacturers, media manufacturers recommend the conditions under which tape cartridges should be handled, transported, stored and used, in order to ensure that the product will perform to standards over this 15- to 30-year time period. Data can be affected by environmental factors such as debris, high temperature or humidity, drastic temperature or humidity changes, and stray magnetic field sources, as well as improper handling of the cartridges by either operations personnel or by the hardware. If not properly handled, high-capacity tape cartridges are susceptible to damage due to the increased linear density, increased track density and subsequent positioning of the data and servo tracks closer to the edges of the tape.

Some basic rules for handling tape cartridges include:

* Stack or carry no more than six cartridges at a time to minimize the risk of dropping the stack

* Do not place cartridges that are dirty or damaged in a drive

* Use the finger grips, if present, to carry a single cartridge

* To prevent tape damage, do not remove leader blocks or open drive doors

* Do not touch tape surfaces, as residue from a fingerprint can create greater head-to-tape separation and result in loss of signal (data)

* Respond to drive messages for cleaning as directed, and only use cleaning cartridges recommended by the hardware provider

* Assure that drives are maintained and serviced per the hardware manufacturer's specifications.

Dropped Cartridges

If a half-inch tape cartridge is dropped, there is always a possibility that the media inside may have been damaged. Even if there is no visible evidence of damage on the outside of the cartridge, the cartridge's life may be shortened. Tape-edge damage or misalignment of internal components, such as hub(s) and tape pack(s), may occur. This damage may not present itself initially, but may develop over time. For this reason, it is recommended that a procedure for retiring dropped cartridges be developed.

Transportation and Storage of Tape Cartridges

Proper packaging of cartridges for shipping is imperative to guarantee the life of the cartridge and the integrity of the data contained on it. Cartridges shipped with inadequate packaging could be damaged, which may result in data loss or reduced cartridge life.

The packaging itself should be strong enough to withstand shipping damage, not allow for cartridges to hit or rub against each other, minimize the internal forces within the package, not contaminate the cartridges, and be able to be used for repeated shipments without degradation of the packaging materials.