Dynamic magnetic information storage or retrieval – Miscellaneous
Reexamination Certificate
2002-12-11
2003-07-01
Renner, Craig A. (Department: 2652)
Dynamic magnetic information storage or retrieval
Miscellaneous
C360S132000, C242S347100, C242S348200
Reexamination Certificate
active
06587307
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This invention relates to a method for protecting data storage media by controlling the internal cartridge environment.
1. Technical Field
This invention relates to an environmentally controlled cartridge for protecting data storage media therein and to a method for controlling the internal cartridge environment.
2. Background Art
Many organizations have long term data storage requirements. Typically, these requirements are addressed by storing important data on media such as magnetic tapes. As those skilled in the art will recognize, however, functional lifetimes of magnetic tape as well as other types of data storage media (disk, tape, optical, magnetic, etc.) are highly sensitive to environmental conditions and, in particular, humidity, airborne pollutants and particulates.
The lifetime of data storage media is generally defined as the length of time it may be archived until data can no longer be read back at the originally specified performance levels. For example, properly manufactured metal particle (MP) tapes operated and stored under controlled conditions can have a life expectancy exceeding 50 years. Such conditions require, however, low controlled humidity on the order of 20-30%. With moderate humidity (50%), the functional lifetime of an MP tape can be reduced to two years. But with elevated humidity (80%) the lifetime can be reduced to one month or less. Typical failure modes include hydrolytic degradation of the binder (“sticky tape”), reductions in binder adhesion, irreversible substrate shrinkage and loss of magnetic remanence or coercivity (signal loss).
In a further example,
FIG. 6
illustrates the relationship between humidity and temperature and the resultant effects on the stability and life of Metal Evaporated (ME) tapes. As shown therein, with temperatures in the approximate range of 16° C to 32° C, humidity strongly influences the lifetime of the media. With an elevated specific humidity (i.e. >0.013), tape instability is experienced. With a moderate level of specific humidity (i.e. 0.08>x>0.013), the optimum operating environment is achieved. Where the specific humidity levels are less than 0.08, high tape wear and low output is experienced. Metal Evaporated (ME) type media has an optimal environmental operating zone requiring a moderate humidity from 40-70% (specific humidity, 0.08>x>0.013).
In the case of the specific humidity requirements of magnetic tapes, the primary options for users to ensure long term data integrity and reliable tape operation have heretofore been to use environmentally controlled tape storage vaults, frequent replacement of tapes or migration of data to new media types. Regardless of the approach, preservation of stored data requires regular media sampling and migration procedures. It is not unusual for large data storage users to perform data migration and/or tape replacement every 3-5 years to insure the integrity of their data; such procedures are costly and can be disruptive to operations.
Humidity is also known to affect magnetic disk media operation as well. For example, the tribology between the head and disk is significantly affected by the relative humidity of the disk/head environment. In broad terms, a very low relative humidity results in poor start-stop tribology and therefore poor reliability. On the other hand, excessive relative humidity contributes to excessive sticking force, when the head is stationary on the disk. Excessive sticking force results in possibly damage to head or suspension components. These problems have motivated the development of environmental control schemes for fixed disk (sealed) magnetic disk drives.
Examples of magnetic disk drive environmental controls are shown in U.S. Pat. No. 4,620,248 issued to Gitzendanner and U.S. Pat. No. 4,863,499 issued to Osendorf. In these patents, the environment of a sealed magnetic disk drive is humidity controlled by utilizing a desiccant. The ingestion of airborne contaminants and particulates during the disk drive's temperature and elevation cycling is minimized by incorporating filter and getter functions into a breather assembly. Unlike the disk media within a sealed disk drive, data storage media such as magnetic tape is exposed to the outside environment during every use. Although this media is housed within a cartridge, the cartridge is opened to permit the drive's access to the media. In addition, the cartridge due to its design does not environmentally protect the tape when removed from the drive.
Consequently, a need has a developed for a method of controlling the internal environment of the cartridge.
DISCLOSURE OF INVENTION
It is an object of the present invention to provide a method to control the humidity levels inside a cartridge for an extended period of time by selectively exposing a charged desiccant to data storage media in response to the insertion and removal of the cartridge from a drive.
It is yet another object of the invention to provide a method to maintain an internal cartridge environment free of chemical and other pollutants.
It is still another object of the invention to provide a method to increase the lifetime of desiccant inside a variety of cartridges.
It is yet another object of the invention to provide a method to selectively expose media to desiccant that is stored within the cartridge.
A method is provided to control the inside environment of a cartridge for protecting data storage media therein from a contaminant in the outside environment. As those skilled in the art will recognize, the contaminant may be either a chemical pollutant, particulate, humidity or any combination thereof. This method includes: providing a closed cartridge with a first chamber for the data storage media and with a second chamber for material to control the contaminants in the inside environment in addition to openable closures for respectively selectively opening and closing the first chamber to the ambient and the second chamber to the first chamber; opening at least one closure for connecting the first chamber to the ambient environment while accessing the data storage media; and opening at least one other closure when the one closure is closed to decontaminate the inside environment of any contaminant which entered the first chamber at least when the first chamber was open to the ambient.
A method of protecting data storage media is also provided. A closed cartridge has a first chamber for storing the data storage media, a second chamber for storing material to control an inside environment of the cartridge, at least one first openable structure for selectively opening and closing the first chamber to the ambient environment, and at least one second openable structure for selectively opening and closing the first chamber to the second chamber. The at least one second openable structure is opened when the at least one first openable structure is closed to decontaminate the inside environment.
A method of controlling an inside environment of a cartridge for protecting data storage media therein from a contaminant from an outside, ambient environment is also provided. A closed cartridge has a first chamber for storing the data storage media and a second chamber in selective communication with the first chamber, The second chamber stores material to control an environment of the first chamber. At least one first openable structure selectively opens and closes the first chamber to the ambient. At least one second openable structure selectively opens and closes the second chamber to the first chamber. The at least one second openable structure is opened to allow the environment of the first chamber to communicate with the material inside the second chamber when the at least one first openable structure is closed.
As those skilled in the art will recognize, the embodiments of this invention can vary depending upon the specific requirements of the data storage media, and the drive that operates upon the media. Accordingly, the particular size, shape and form of the cartridge, i
Leonhardt Michael L.
Raymond Robert M.
Brooks & Kushman P.C.
Renner Craig A.
Storage Technology Corporation
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