Method for efficient delivery of clustered data via adaptive TCP connection migration
View Patent ↗The present invention relates generally to a method for efficient I/O handling in a cluster-based architecture. According to one aspect, the invention enables efficient scheduling of TCP connection migrations within a cluster. According to another aspect, the invention enables I/Os performed as TCP handoff operations to coexist on the same TCP/IP connection with I/Os performed as remote operations.
1. A method comprising:
receiving a network connection at a first node of a storage cluster;
receiving a first I/O request at the first node via the connection;
processing the first I/O request at the first node;
receiving a second I/O request at the first node via the connection;
forwarding the second I/O request to a second node of the storage cluster;
processing the second I/O request at the second node while maintaining the network connection at the first node; and
migrating the connection to the second node after completing the processing of the first I/O request at the first node and after forwarding the second I/O request to the second node.
2. A method according to claim 1 , further comprising:
logging statistics corresponding to the first and second I/O requests; and
determining when to migrate the connection to the second node based on an evaluation of the statistics.
3. A method according to claim 1 , further comprising:
maintaining a directory of data associated with the storage cluster; and
identifying the second node using the directory.
4. A method according to claim 1 , wherein the step of migrating the connection is performed transparently to a client associated with the connection.
5. A method according to claim 1 , wherein the connection uses TCP.
6. A method according to claim 4 , wherein the connection uses TCP.
7. A method according to claim 1 , further comprising sending a reply to the first I/O request from the first node before migrating the connection.
8. A method according to claim 7 , further comprising sending a reply to the second I/O request from the second node after migrating the connection.
9. A method comprising:
receiving a network connection at a first node of a storage cluster;
receiving a first I/O request at the first node via the connection;
processing the first I/O request at the first node;
receiving a second I/O request at the first node via the connection;
determining whether to handoff the second I/O request to a second node of the storage cluster;
if the determination is to handoff the second I/O request:
processing the second I/O request at the second node, and
migrating the connection to the second node after completing the processing of the first I/O request at the first node and after forwarding the second I/O request to the second node;
if the determination is to not handoff the second I/O request:
processing the second I/O request at the second node, and
forwarding results of processing the second I/O request to the first node.
10. A method according to claim 9 , further comprising:
maintaining a directory of data associated with the storage cluster; and
identifying the second node using the directory.
11. A method according to claim 9 , wherein the step of migrating the connection is performed transparently to a client associated with the connection.
12. A method according to claim 9 , wherein the connection uses TCP.
13. A method according to claim 11 , wherein the connection uses TCP.
14. A storage apparatus comprising:
a first node that receives a network connection and a first I/O request via the connection;
a second node that processes a second I/O request received at the first node while maintaining the network connection at the first node; and
a handoff mechanism that migrates the connection to the second node after processing of the first I/O request at the first node is completed and after processing of the second I/O request at the second node has started.
15. An apparatus according to claim 14 , further comprising:
statistics corresponding to the processing of the first and second I/O requests,
wherein the handoff mechanism uses the statistics to determine when to migrate the connection to the second node.
16. An apparatus according to claim 14 , further comprising:
a directory of data associated with the storage cluster,
wherein the second node is identified using the directory.
17. An apparatus according to claim 14 , wherein the handoff mechanism is adapted to migrate the connection transparently to a client associated with the connection.
18. An apparatus according to claim 14 , wherein the connection uses TCP.
19. An apparatus according to claim 17 , wherein the connection uses TCP.
20. An apparatus according to claim 14 , wherein the handoff mechanism is further adapted to determine whether to handoff the second I/O request to a second node of the storage cluster, and wherein if the determination is to handoff the second I/O request:
the handoff mechanism causes the second I/O request to be processed at the second node, and migrates the connection to the second node after processing of the first I/O request at the first node is completed and after processing of the second I/O request at the second node has started;
and wherein if the determination is to not handoff the second I/O request:
the handoff mechanism causes the second I/O request to be processed at the second node, and further causes results of processing the second I/O request to be forwarded to the first node.