Data relay device, storage device, and response delay monitoring method

• US 20080155358A1
• Filed: 10/18/2007
• Published: 06/26/2008
• Est. Priority Date: 12/26/2006
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Arataki, Nina, Ohyama, Sadayuki
• Granted Patent: US 7,873,880 B2
• Time in Patent Office: Days
• US Class Current: 714/47
• CPC Class Codes: G06F 11/0727 in a storage system, e.g. in a DASD or network based storage system drivers for digital recording or reproducing units G06F3/06; circuits for error detection or correction within digital recording or reproducing units G11B20/18; for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS], H04L67/1097
• CPC Class Codes: G06F 11/0757 by exceeding a time limit, i.e. time-out, e.g. watchdogs

Abstract

A data relay device relays a read request from a source device to a destination device and relays data corresponding to the read request from the destination device to the source device. The data relay device monitors elapsed time from a time point at which a read request is relayed to the destination device. When the elapsed time reaches warning time or error time, the data relay device sends a warning message or an error message to the source device.

Claims

1. A data relay device that relays a read request from a source device to a destination device and relays data corresponding to the read request from the destination device to the source device, the data relay device comprising:

a relay unit that receives a read request from the source device and relays the read request to the destination device;

a counting unit that counts elapsed time from a time point at which the relay unit relays the read request to the destination device;

a monitoring unit that monitors whether the elapsed time has reached a threshold; and

an informing unit that informs the source device that the elapsed time has reached the threshold upon result of monitoring by the monitoring unit indicating that the elapsed time has reached the threshold.

2. The data relay device according to claim 1, further comprising a receiving unit that receives data from the destination device in response to a read request, wherein

the counting unit suspends counting of the elapsed time for the read request.

3. The data relay device according to claim 1, wherein the threshold is shorter than a period of time judged as a time-out error in the source device.

4. The data relay device according to claim 1, wherein the monitoring unit monitors whether the elapsed time has reached an error time of time that is same as the time when error occurs in the source device.

5. The data relay device according to claim 1, further comprising a storing unit that separately stores therein a read request with elapsed time that has reached the threshold and a read request with elapsed time that has not reached the threshold.

6. The data relay device according to claim 5, wherein the storing unit stores therein identification information for identifying the read request with elapsed time that has reached the threshold, flag information indicating whether data is received in response to the read request, time required for the source device to receive the data, and a type of delay corresponding to amount of delay in an associated manner.

7. The data relay device according to claim 1, further comprising a managing unit that manages identification information for identifying the read request, elapsed time, and flag information indicating whether there is any data in response to the read request.

8. The data relay device according to claim 1, further comprising an interrupting unit that interrupts relay of data received in response to the read request when the elapsed time reaches the threshold that is equivalent to a period of time judged as a time-out error in the source device.

9. The data relay device according to claim 8, wherein the interrupting unit discards the data when the elapsed time reaches the threshold.

10. A storage device that stores, in a storing medium, user data that is read by a host computer, the storage device comprising:

a plurality of channel adapters each of which capable of outputting a read request to read user data from the storing medium based on a command from the host computer;

a switch that receives a read request from a first channel adapter from among the channel adapters and relays the read request; and

a cache controller that receives the read request from the switch, reads user data corresponding to the read request from the storing medium, and sends the user data to the first channel adapter through the switch, wherein the switch includes

a relay unit that receives the read request from the first channel adapter and relays the read request to the cache controller;

a counting unit that counts elapsed time from a time point at which the relay unit relays the read request to the cache controller up to a time point at which data is received from the cache controller in response to the read request;

a monitoring unit that monitors whether the elapsed time has reached a threshold; and

an informing unit that informs the first channel adapter that the elapsed time has reached the threshold upon result of monitoring by the monitoring unit indicating that the elapsed time has reached the threshold.

11. A method of monitoring a delay in a response by a data relay device that relays a read request from a source device to a destination device and relays data corresponding to the read request from the destination device to the source device, the method comprising:

receiving a read request from the source device and relaying the read request to the destination device;

counting elapsed time from a time point at which the read request is relayed to the destination device;

monitoring whether the elapsed time has reached a threshold; and

informing the source device that the elapsed time has reached the threshold when it is determined at the monitoring that the elapsed time has reached the threshold.

12. The method according to claim 11, further comprising:

receiving data from the destination device in response to a read request; and

suspends counting of the elapsed time for the read request.

13. The method according to claim 11, wherein the threshold is shorter than a period of time judged as a time-out error in the source device.

14. The method according to claim 11, wherein the monitoring includes monitoring whether the elapsed time has reached an error time of time that is same as the time when error occurs in the source device.

15. The method according to claim 11, further comprising separately storing in a storing unit a read request with elapsed time that has reached the threshold and a read request with elapsed time that has not reached the threshold.

16. The method according to claim 15, wherein the storing includes storing in the storing unit identification information for identifying the read request with elapsed time that has reached the threshold, flag information indicating whether data is received in response to the read request, time required for the source device to receive the data, and a type of delay corresponding to amount of delay in an associated manner.

17. The method according to claim 11, further comprising managing identification information for identifying the read request, elapsed time, and flag information indicating whether there is any data in response to the read request.

18. The method according to claim 11, further comprising interrupting relay of data received in response to the read request when the elapsed time reaches the threshold that is equivalent to a period of time judged as a time-out error in the source device.

19. The method according to claim 18, wherein the interrupting includes discarding the data when the elapsed time reaches the threshold.