Browse Prior Art Database

Buy-what-you-need and When-you-need-it Data Cartridge Disclosure Number: IPCOM000015243D
Original Publication Date: 2001-Sep-01
Included in the Prior Art Database: 2003-Jun-20

Publishing Venue



Figure 1 shows the preferred embodiment of our invention. A data cartridge load request 10 is received by a human user, a library with a robotic picker, or an automatic cartridge loader (ACL). An NVRAM (NonVolatile Random Access Memory) chip which holds the directory contents of the data cartridge is read 12 via any of several different methods, including (a) the grippers of the robotic picker or the ACL having an interface for reading the NVRAM, or (b) the user, the robotic picker, or the ACL holding the NVRAM against a stationary interface. Specific information about this NVRAM is found in US patent 6,172,833. Then, the contents of the NVRAM are processed by either the host, control unit, or I/O device itself in step 14 , to include both reading the directory contents of the data cartridge and gathering the available capacity in that data cartridge, which may be less than the total capacity if the user only purchased a portion of the total capacity. Step 14 flows in parallel to steps 30 and 16 . In step 16 , the media is positioned for I/O. This includes mounting the data cartridge and seeking to the I/O region of the cartridge. In step 30 , the query is made as to whether there is any write workload in the I/O queue. If there is not, the process flows from step 30 to step 42 , where the I/O is performed once the media is positioned in step 16 . If there is write workload in step 30 , the process flows to step 32 , where the information in the NVRAM chip is used to sum the sizes of all of the files stored in the data cartridge. Then, in step 34 , the available capacity is calculated by subtracting the used capacity from the user purchased capacity. The process flows to step 36 , where the write workload size is compared against the available capacity calculated in step 34 . If the write size is less than the available capacity, the process flows to step 42 , where the I/O is performed. If the write size is not less than the available capacity, then the process flows to step 38 where the user purchases additional available capacity which was held in reserve in the data cartridge. The user does this via the internet, email, or over the telephone. After purchasing the additional capacity, the user is given a password which is unique to the data cartridge and used to update the NVRAM in step 40 with the additional capacity purchased. The process then flows from step 40 to step 36 where the size of the write workload is again compared against the available capacity. Once the write workload will fit on the data cartridge, the process flows to step 42 where the I/O is performed. Once the I/O is completed in step 42 , the process flows to step 44 where the cartridge is dismounted and the NVRAM is updated with the new directory contents of the data cartridge. Then the process flows to step 50 and exits. This invention is preferably used for lowering the entry price for tape cartridges, where the user buys only a portion of the tape cartridge and then increases the capacity when that capacity is needed. However, this invention could equally be applied to multi-layer DVD (Digital Versatile Disk), magneto-optical, phase-change, holographic, floppy disk, or hard disk removable cartridges, and hard disk drives themselves. The user is able to “unlock” additional capacity in the cartridge by purchasing that capacity when needed. Such unlocking with a password could be done for a population of cartridges in a large account or glass house. This permits product differentiation without physically having different sized products, which is especially valuable in the tape industry. Alternatives to storing the data in a dedicated NVRAM chip include use of the