Method and apparatus for recording compressed data on DAT media

Claim 1

A method of operating a data system including a standard format tape drive to enhance the storage capacity of magnetic media used therewith beyond the capacity of the magnetic media when formatted in said standard format in which record groups each have a fixed, predetermined number of frames of fixed data size, the method comprising the steps of: operating a standard format tape drive to exchange data in media record groups with a buffer, each such media record group including frames of fixed data size; operating a data utilization device to exchange data in standard format record groups with the buffer, each such standard format record group including a fixed, predetermined number of frames of data of said fixed data size; operating a data record group compression device associated with the buffer to form compressed record groups from standard format record groups transferred to the buffer from the data utilization device, each compressed record group being associated with a particular standard record group and including frames of data of said fixed data size; substituting a compressed record group for the standard format record group associated therewith to form a media record group when the data in said standard record group is to be written to the tape drive if the number of frames of data in the compressed record group is less than said fixed, predetermined number; operating a data record group decompression device associated with the buffer to form standard record groups from compressed record groups transferred to the buffer from the tape drive; and substituting a standard record group so formed for the compressed record group associated therewith when the data in the compressed record group is to be read by the data utilization device.

Claim 2

A method of operating a data system including a standard format tape drive to enhance the storage capacity of magnetic media used therewith beyond the capacity of the magnetic media when formatted in said standard format in which record groups each have a fixed, predetermined number of frames of fixed data size, the method comprising the steps of: operating a standard format tape drive to exchange data in media record groups with a buffer, each such media record group including frames of fixed data size; operating a data utilization device to exchange data in standard format record groups with the buffer, each such standard format record group including a fixed, predetermined number of frames of data of said fixed data size; operating a data record group compression device associated with the buffer to form compressed record groups from standard format record groups transferred to the buffer from the data utilization device, each compressed record group being associated with a particular standard record group and including frames of data of said fixed data size; substituting a compressed record group for the standard format record group associated therewith to form a media record group when the data in said standard record group is to be written to the tape drive if the number of frames of data in the compressed record group is less than said fixed, predetermined number; operating a data record group decompression device associated with the buffer to form standard record groups from compressed record groups transferred to the buffer from the tape drive; and substituting a standard record group so formed for the compressed record group associated therewith when the data in the compressed record group is to be read by the data utilization device.