Dynamically changing a buffer flush threshold of a tape drive based on historical transaction size

A computer program product for dynamically changing a buffer threshold in a tape drive, the computer program product comprising a non-transitory computer readable storage medium having program code embodied therewith, the program code readable/executable by a processor to:

• collect tape drive writing information while receiving data from a host, the tape drive writing information comprising:
• a transaction size (S) indicating an amount of data received by the tape drive and stored in a drive buffer between receiving synchronization (sync) commands;
• and
• a host transfer rate (H) indicating a speed at which data is received by the tape drive;
• determine that the drive buffer is emptied of data;
• calculate a write size (s) indicating an amount of data from the transaction size (S) left to be written to a tape by the tape drive prior to a next anticipated sync command;
• set the buffer threshold (b) to a smaller value when the transaction size (S) is less than a size (B) of the buffer, the buffer threshold (b) indicating an amount of data stored in the drive buffer that triggers a back hitch that precedes writing data from the drive buffer to the tape;
• set the buffer threshold (b) to the smaller value when an absolute difference between the transaction size (S) and the write size (s) is greater than or equal to the buffer size (B);
• and
• set the buffer threshold (b) to a larger value when the transaction size (S) is not less than the buffer size (B) and/or the absolute difference between the transaction size (S) and the write size (s) is less than the buffer size (B).

A method for dynamically changing a buffer threshold in a tape drive, the method comprising:

• collecting tape drive writing information while receiving data from a host, the tape drive writing information comprising:
• a transaction size (S) indicating an amount of data received by the tape drive and stored in a drive buffer between receiving synchronization (sync) commands;
• and
• a host transfer rate (H) indicating a speed at which data is received by the tape drive;
• determining that the drive buffer is emptied of data;
• calculating a write size (s) indicating an amount of data from the transaction size (S) left to be written to a tape prior to a next anticipated sync command;
• setting a buffer threshold (b) to a smaller value when the transaction size (S) is less than a size (B) of the buffer, the buffer threshold (b) indicating an amount of data stored in the drive buffer that triggers a back hitch that precedes writing data from the drive buffer to the tape;
• setting the buffer threshold (b) to the smaller value when an absolute difference between the transaction size (S) and the write size (s) is greater than or equal to the buffer size (B);
• and
• setting the buffer threshold (b) to a larger value when the transaction size (S) is not less than the buffer size (B) and/or the absolute difference between the transaction size (S) and the write size (s) is less than the buffer size (B).