MULTI-HOST CONCURRENT WRITING TO MAGNETIC TAPE

• US 20100299477A1
• Filed: 05/20/2009
• Published: 11/25/2010
• Est. Priority Date: 05/20/2009
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Brume, Shawn O., Knibloe, Christine R., Jangaba, Fahnmusa C., Swanson, David L.
• Granted Patent: US 8,250,299 B2
• Time in Patent Office: Days
• US Class Current: 711/111
• CPC Class Codes: G06F 3/0613 in relation to throughput
• CPC Class Codes: G06F 3/0658 Controller construction arrangements
• CPC Class Codes: G06F 3/0682 Tape device

Abstract

According to one embodiment, a method for storing data on a magnetic tape comprises receiving data from two different hosts and simultaneously writing the data from the hosts to the magnetic tape using multiple transducers. In another approach, a method for storing data on a magnetic tape comprises receiving requests to establish a concurrent reservation from multiple hosts and allocating a unique stripe in a wrap to each of the hosts that sent the requests, wherein the wrap is a collection of data tracks to be written simultaneously in one direction of tape movement by multiple transducers of a tape head, and the wrap is logically divided into the stripes. Also, the method includes receiving data from the hosts and simultaneously writing the data from the hosts to the magnetic tape using the multiple transducers. Other systems and methods concerning storing data on magnetic tapes are described as well.

Claims

1. A method for storing data on a magnetic tape, the method comprising:

receiving data from two different hosts; and

simultaneously writing the data from the hosts to the magnetic tape using multiple transducers.

2. The method as recited in claim 1, further comprising storing an indication that data from multiple hosts has been simultaneously written to the magnetic tape.

3. The method as recited in claim 1, wherein data is received from each of the hosts at a respective incoming data rate, and further comprising selecting a data write rate that about matches a faster of the incoming data rates from the hosts.

4. The method as recited in claim 3, wherein a dataset spacing of the data corresponding to the host having a slower of the incoming data rates is relaxed.

5. The method as recited in claim 1, wherein data is received from each of the hosts at a respective incoming data rate, and further comprising selecting a data write rate that about matches a slower of the incoming data rates from the hosts.

6. The method as recited in claim 5, further comprising requesting a temporary suspension of data transfer from the host having the faster of the incoming data rates.

7. The method as recited in claim 1, wherein data is received from each of the hosts at a respective incoming data rate, and further comprising selecting a data write rate that is between a faster and a slower of the incoming data rates from the hosts.

8. The method as recited in claim 7, wherein a dataset spacing of the data corresponding to the host having a slower of the incoming data rates is relaxed.

9. The method as recited in claim 1, wherein a collection of data tracks written simultaneously in one direction of tape movement by the multiple transducers is a wrap, wherein the wrap is logically divided into two stripes, each stripe being allocated to one of the hosts, each stripe being associated with a plurality of the transducers, wherein the data corresponding to each host is simultaneously written to the stripe allocated to each respective host.

10. The method as recited in claim 9, further comprising receiving a request to establish a concurrent reservation from one of the hosts, and further comprising allocating one of the stripes in the wrap to the host that sent the request.

11. The method as recited in claim 1, further comprising storing an indication that data from multiple hosts has been simultaneously written to the magnetic tape, wherein data is received from each of the hosts at a respective incoming data rate, and further comprising selecting a data write rate based on the incoming data rates from the hosts, wherein a collection of data tracks written simultaneously in one direction of tape movement by the multiple transducers is a wrap, wherein the wrap is logically divided into two stripes, each stripe being allocated to one of the hosts, each stripe being associated with a plurality of the transducers, wherein the data corresponding to each host is simultaneously written to the stripe allocated to each respective host.

12. A method for storing data on a magnetic tape, the method comprising:

receiving requests to establish a concurrent reservation from multiple hosts;

allocating a unique stripe in a wrap to each of the hosts that sent the requests, wherein the wrap is a collection of data tracks to be written simultaneously in one direction of tape movement by multiple transducers of a tape head, wherein the wrap is logically divided into the stripes;

receiving data from the hosts; and

simultaneously writing the data from the hosts to the magnetic tape using the multiple transducers.

13. A system for storing data on a magnetic tape, the system comprising:

a magnetic head having multiple transducers;

a drive mechanism for passing a magnetic tape over the head;

a controller in communication with the head;

inputs for receiving data from two different hosts; and

logic for simultaneously writing the data from the hosts to the magnetic tape using the multiple transducers.

14. The system as recited in claim 13, further comprising logic for storing an indication that data from multiple hosts has been simultaneously written to the magnetic tape.

15. The system as recited in claim 13, wherein data is received from each of the hosts at a respective incoming data rate, and further comprising logic for selecting a data write rate that about matches a faster of the incoming data rates from the hosts.

16. The system as recited in claim 15, wherein a dataset spacing of the data corresponding to the host having a slower of the incoming data rates is relaxed.

17. The system as recited in claim 13, wherein data is received from each of the hosts at a respective incoming data rate, and further comprising logic for selecting a data write rate that about matches a slower of the incoming data rates from the hosts.

18. The system as recited in claim 17, wherein a temporary suspension of data transfer is requested from the host having the faster of the incoming data rates.

19. The system as recited in claim 13, wherein data is received from each of the hosts at a respective incoming data rate, and further comprising logic for selecting a data write rate that is between a faster and a slower of the incoming data rates from the hosts.

20. The system as recited in claim 19, wherein a dataset spacing of the data corresponding to the host having a slower of the incoming data rates is relaxed.

21. The system as recited in claim 13, wherein a collection of data tracks written simultaneously in one direction of tape movement by the multiple transducers is a wrap, wherein the wrap is logically divided into two stripes, each stripe being allocated to one of the hosts, each stripe being associated with a plurality of the transducers, wherein the data corresponding to each host is simultaneously written to the stripes allocated to each respective host.

22. The system as recited in claim 21, further comprising receiving a request to establish a concurrent reservation from one of the hosts, and further comprising allocating one of the stripes in the wrap to the host that sent the request.

23. The system as recited in claim 13, further comprising logic for storing an indication that data from multiple hosts has been simultaneously written to the magnetic tape, wherein data is received from each of the hosts at a respective incoming data rate, and further comprising logic for selecting a data write rate based on the incoming data rates from the hosts, wherein a collection of data tracks written simultaneously in one direction of tape movement by the multiple transducers is a wrap, wherein the wrap is logically divided into two stripes, each stripe being allocated to one of the hosts, each stripe being associated with a plurality of the transducers, wherein the data corresponding to each host is simultaneously written to the stripe allocated to each respective host.

24. A magnetic tape cartridge comprising a magnetic tape having stored thereon data that was received from two different hosts and written to the magnetic tape simultaneously.

25. The magnetic tape cartridge as recited in claim 24, further comprising a computer-readable indication that data from multiple hosts has been simultaneously written to the magnetic tape.

26. The magnetic tape cartridge as recited in claim 24, wherein the data from the two different hosts is present on the magnetic tape in stripes, wherein each stripe includes multiple, simultaneously-written data tracks.

27. The magnetic tape cartridge as recited in claim 26, wherein at least one of the data tracks of a first of the stripes lies on the magnetic tape between data tracks of a second of the stripes written concurrently therewith.

28. A magnetic tape cartridge comprising a magnetic tape being formatted for multiple-host concurrent writing, wherein the cartridge includes an indication that the tape is formatted for multiple-host concurrent writing.

29. The magnetic tape cartridge as recited in claim 28, wherein the indication is written on the magnetic tape.

30. The magnetic tape cartridge as recited in claim 28, wherein the indication is stored in a nonvolatile memory coupled to the cartridge.