Method for extraction of a variable length record from fixed length sectors on a disk drive and for reblocking remaining records in a disk track

A memory media for enabling a host processor which employs variable length (VL) records to communicate with disk storage means which employs fixed length (FL) sectors for storage of said VL records, said memory media comprising:

• a) means for controlling a processor to derive a first control data structure for an update VL record, said first control data structure including information describing segments of said update VL record;
• b) means for enabling a disk controller to determine a disk track that includes a FL sector wherein am old VL record commences that corresponds to said update VL record;
• c) means for enabling a disk drive coupled to said disk controller to read each FL sector in said disk track and to enable said processor to create a control data structure which includes information describing each VL record stored in said disk track;
• d) means for causing said processor to substitute in a control data structure for said old VL record that corresponds to said update VL record, information regarding update data from said first control data structure;
• and
• e) means for controlling said disk controller and said disk drive to record in said disk track, data indicated by each control data structure determined by said means c) and d).

A method for enabling a reading of a variable length (VL) record that is stored in multiple fixed length (FL) sectors on a disk drive, to commence at any FL sector which includes a portion of said Vl record, said method comprising the steps of:

• (a) including in each said multiple FL sectors, field descriptors which describe each portion of a VL record that is stored therein;
• (b) deriving a control data block for at least one said VL record;
• (c) commencing to read FL sectors from said disk drive at a FL sector that includes an intermediate field descriptor other than a first field descriptor which occurs at a beginning of a VL record, and employing information from said intermediate field descriptor to identify a corresponding control data block;
• and
• (d) later, during a rotation of said disk drive, employing information from one or more FL sectors to enter data into said corresponding control data block, up to and including a FL sector which includes said intermediate field descriptor.