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

摘要

According to one embodiment, a method for dynamically changing a buffer threshold in a tape drive includes determining that a drive buffer is emptied of data, calculating a write size indicating an amount of data from a transaction size left to be written to a tape prior to a next anticipated sync command, setting a buffer threshold that triggers a back hitch to a smaller value when the transaction size is less than a buffer size, setting the buffer threshold to the smaller value when an absolute difference between the transaction size and the write size is greater than or equal to the buffer size, and setting the buffer threshold to a larger value when the transaction size is not less than the buffer size and/or the absolute difference between the transaction size and the write size is less than the buffer size.

主权项

1. A tape drive, comprising a drive buffer, a processor, and logic integrated with and/or executable by the processor, the logic being configured to cause the 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 the drive buffer between receiving synchronization (sync) commands; anda 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 prior to a next anticipated sync command; set 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; 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).