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US 7,710,681 B2Granted
Optimizing tape speed for a sync operation
AssigneeInternational Business Machines Corporation
InventorsHiroshi Itagaki, James Mitchell Karp, Takashi Katagiri
Life of this patent
Estimating the term…
Abstract
Provided are techniques for determining a tape speed for a next sync operation. A sync command is received. An average transaction size and an average host transfer rate of a set of previous sync operations are calculated. The tape speed for the next sync operation is determined using the average transaction size, the average host transfer rate, and a backhitch time. Data is written to a tape cartridge using the determined tape speed.
Claims30
A computer-implemented method for determining a tape speed for a next sync operation, comprising:
- receiving a sync command that writes data in a tape drive data buffer onto a tape cartridge while a backhitch is being performed;
- calculating an average transaction size and an average host transfer rate of a set of previous sync operations;
- determining the tape speed for the next sync operation using the average transaction size, the average host transfer rate, and a backhitch time by calculating:
- T(i)=Backhitch_Time(i)+Average_Transaction_Size/Media_Transfer_Rate(i),
- wherein the Media_Transfer_Rate(i) is determined based on a density of a tape;
- and
- writing data to a tape cartridge using the determined tape speed.
4 more elements
A computer-implemented method for determining a tape speed for a sync operation, comprising:
- calculating a first variable “S” that represents an expected time to transfer data from a first source to a tape drive;
- calculating a second variable “T” that represents an expected time of a sync operation, wherein the second variable is dependent on a current tape speed and a third variable “i” that represents another tape speed by calculating:
- T(i)=Backhitch_Timed)+Average_Transaction_Size/Media_Transfer_Rated(i),
- wherein the Backhitch_Timed) is dependent on the current tape speed and the third variable “i”, and wherein the Media_Transfer_Rate is dependent on the third variable “i”;
- in response to determining that a value of the first variable is greater than a value of the second variable,
- determining whether there is a slower speed available that is slower than a value of the third variable;
- and
- in response to determining that there is no slower speed, outputting the value of the third variable as the tape speed for the sync operation.
5 more elements
A computer-implemented method for determining a tape speed for a sync operation, comprising:
- calculating a first variable “S” that represents an expected time to transfer data from a first source to a tape drive;
- calculating a second variable “T” that represents an expected time of a sync operation, wherein the second variable is dependent on a current tape speed and a third variable “i” that represents another tape speed, wherein calculating the second variable comprises:
- generating a backhitch time that is dependent on the current tape speed and the third variable, wherein generating the backhitch time comprises calculating:
- Current_Tape_Speed/A+√{square root over ((2*(Y−Z)/A))}+i/A
- where A represents an acceleration, Y represents a position to which deceleration occurs, and Z represents a position to which there is a backward move;
- and
- dividing an average transaction size by a media transfer rate, wherein the media transfer rate is dependent on the third variable “i”;
- and
- in response to determining that a value of the first variable is greater than a value of the second variable,
- determining whether there is a slower speed available that is slower than a value of the third variable;
- and
- in response to determining that there is no slower speed, outputting the value of the third variable as the tape speed for the sync operation.
9 more elements
A computer program product comprising a computer-readable medium including a computer readable program, wherein the computer readable program when executed on a computer causes the computer to:
- receive a sync command that writes data in a tape drive data buffer onto a tape cartridge while a backhitch is being performed;
- calculate an average transaction size and an average host transfer rate of a set of previous sync operations;
- determine the tape speed for the sync operation using the average transaction size, the average host transfer rate, and a backhitch time by calculating:
- T(i)=Backhitch_Time(i)+Average_Transaction_Size/Media_Transfer_Rate(i),
- wherein the Media_Transfer_Rate(i) is determined based on a density of a tape;
- and
- write data to a tape cartridge using the determined tape speed.
4 more elements
A computer program product comprising a computer-readable medium including a computer readable program, wherein the computer readable program when executed on a computer causes the computer to:
- calculate a first variable “S” that represents an expected time to transfer data from a first source to a tape drive;
- calculate a second variable “T” that represents an expected time of a sync operation, wherein the second variable is dependent on a current tape speed and a third variable “i” that represents another tape speed by calculating:
- T(i)=Backhitch_Time(i)+Average_Transaction_Size/Media_Transfer_Rate(i),
- wherein the Backhitch_Time(i) is dependent on the current tape speed and the third variable “i”, and wherein the Media_Transfer_Rate is dependent on the third variable “i”;
- and
- in response to determining that a value of the first variable is greater than a value of the second variable,
- determine whether there is a slower speed available that is slower than a value of the third variable;
- and
- in response to determining that there is no slower speed, output the value of the third variable as the tape speed for the sync operation.
6 more elements
A computer program product comprising a computer-readable medium including a computer readable program, wherein the computer readable program when executed on a computer causes the computer to:
- calculate a first variable “S” that represents an expected time to transfer data from a first source to a tape drive;
- calculate a second variable “T” that represents an expected time of a sync operation, wherein the second variable is dependent on a current tape speed and a third variable “i” that represents another tape speed, wherein calculating the second variable comprises:
- generating a backhitch time that is dependent on the current tape speed and the third variable, wherein generating the backhitch time comprises calculating:
- Current_Tape_Speed/A+√{square root over ((2*(Y−Z)/A))}i/A
- where A represents an acceleration, Y represents a position to which deceleration occurs, and Z represents a position to which there is a backward move;
- and
- dividing an average transaction size by a media transfer rate, wherein the media transfer rate is dependent on the third variable “i”;
- and
- in response to determining that a value of the first variable is greater than a value of the second variable,
- determine whether there is a slower speed available that is slower than a value of the third variable;
- and
- in response to determining that there is no slower speed, output the value of the third variable as the tape speed for the sync operation.
9 more elements
A system for determining a tape speed for a sync operation, comprising:
- hardware logic capable of performing operations, the operations comprising:
- receiving a sync command that writes data in a tape drive data buffer onto a tape cartridge while a backhitch is being performed;
- calculating an average transaction size and an average host transfer rate of a set of previous sync operations;
- determining the tape speed for the sync operation using the average transaction size, the average host transfer rate, and a backhitch time by calculating:
- T(i)=Backhitch_Time(i)+Average_Transaction_Size/Media_Transfer_Rate(i),
- wherein the Media_Transfer_Rate(i) is determined based on a density of a tape;
- and
- writing data to a tape cartridge using the determined tape speed.
5 more elements
A system for determining a tape speed for a sync operation, comprising:
- hardware logic capable of performing operations, the operations comprising:
- calculating a first variable “S” that represents an expected time to transfer data from a first source to a tape drive;
- calculating a second variable “T” that represents an expected time of a sync operation, wherein the second variable is dependent on a current tape speed and a third variable “i” that represents another tape speed by calculating:
- T(i)=Backhitch_Timed(i)+Average_Transaction_Size/Media_Transfer_Rate(i),
- wherein the Backhitch_Time(i) is dependent on the current tape speed and the third variable “i”, and wherein the Media_Transfer_Rate is dependent on the third variable “i”;
- and
- in response to determining that a value of the first variable is greater than a value of the second variable,
- determining whether there is a slower speed available that is slower than a value of the third variable;
- and
- in response to determining that there is no slower speed, outputting the value of the third variable as the tape speed for the sync operation.
7 more elements
A system for determining a tape speed for a sync operation, comprising:
- hardware logic capable of performing operations, the operations comprising:
- calculating a first variable “S” that represents an expected time to transfer data from a first source to a tape drive;
- calculating a second variable “T” that represents an expected time of a sync operation, wherein the second variable is dependent on a current tape speed and a third variable “i” that represents another tape speed, wherein operations for calculating the second variable comprises:
- generating a backhitch time that is dependent on the current tape speed and the third variable, wherein operations for generating the backhitch time further comprises calculating:
- Current_Tape_Speed/A+√{square root over ((2*(Y−Z)/A))}+i/A
- where A represents an acceleration, Y represents a position to which deceleration occurs, and Z represents a position to which there is a backward move and
- dividing an average transaction size by a media transfer rate, wherein the media transfer rate is dependent on the third variable “i” and
- in response to determining that a value of the first variable is greater than a value of the second variable,
- determining whether there is a slower speed available that is slower than a value of the third variable;
- and
- in response to determining that there is no slower speed, outputting the value of the third variable as the tape speed for the sync operation.
8 more elements
Dependencies are inferred from the claim text.