Multi-node replication systems, devices and methods

• US 20080288811A1
• Filed: 10/05/2007
• Published: 11/20/2008
• Est. Priority Date: 05/17/2007
• Status: Active Grant

• Current Assignee: Micro Focus Software, Inc. (Open Text Corporation)
• Original Assignee: Novell Incorporated (Open Text Corporation)
• Inventors: Sudhakar, Gosukonda Naga Venkata Satya
• Granted Patent: US 8,346,719 B2
• Time in Patent Office: Days
• US Class Current: 714/4
• CPC Class Codes: G06F 11/2097 maintaining the standby controller/processing unit updated initialisation or re-synchronisation thereof G06F11/1658 and subgroups
• CPC Class Codes: G06F 16/10 File systems; File servers

Abstract

Replication techniques are presented. According to an embodiment of a method, a node of a replicated storage network is assigned to be an owner of a data block to issue write memory block commands. The network includes at least two nodes including the node assigned to be the owner. If a read memory block command is received to read the data block, a read_lock is issued for the data block, the data block is read, and the read_lock for the data block is released. If a write memory block command is received to write new data to the data block, a write_lock is issued for the data block, the data block is written and a version associated with the data block is incremented, and the write_lock for the data block is released.

Claims

1. A method, comprising:

assigning a node of a replicated storage network to be an owner of a data block to issue write memory block commands, the network including at least two nodes including the node assigned to be the owner;

if a read memory block command is received to read the data block, issuing a read_lock for the data block, reading the data block, and releasing the read_lock for the data block; and

if a write memory block command is received to write new data to the data block, issuing a write_lock for the data block, writing the data block and incrementing a version associated with the data block, and releasing the write_lock for the data block.

2. The method of claim 1, wherein the replicated storage network includes a plurality of data blocks, and assigning a node includes mapping the plurality of data blocks across all nodes in the network.

3. The method of claim 1, wherein:

the replicated storage network includes a plurality of data blocks, each data block being identified by a unique block number;

each node of the network is identified by a unique node number; and

assigning a node includes dividing the block number of the data block by the number of nodes in the network and identifying a resulting remainder value; and

assigning a node with a node number that corresponds to the remainder value to be the owner of the data block.

4. The method of claim 1, wherein:

the replicated storage network includes a plurality of data blocks, each data block being identified by a unique block number;

each node of the network is identified by a unique node number; and

assigning a node includes using a mapping function that maps a given block number to a node.

5. The method of claim 1, wherein issuing a read_lock includes issuing a read_lock specific to the data block, and issuing a write_lock includes issuing a write_lock specific to the data block.

6. The method of claim 5, wherein issuing the write_lock includes issuing a distributed write_lock for the network.

7. The method of claim 1, wherein assigning the node includes comparing a number of times a node acts as an owner node to a number of times other nodes act as an owner node to generate a comparison result;

and adjusting assigned ownerships to distribute ownership activity among network nodes using the comparison result.

8. A method of replicating data in a storage network having at least two nodes, comprising:

assigning nodes of the network to be owners of data blocks to issue write memory block commands, each data block being owned by one node;

performing a local write of a first data block to an owner node for the first data block, including performing a first process at the owner node and performing a second process at the non-owner nodes in the network;

wherein the first process at the owner node includes;

issuing a write_lock request for the first data block to all nodes in the network;

copying old data for the first data block to a memory location, and issuing a write command to non-owner nodes in the network to write new data for the first data block;

waiting for the acknowledgment from each non-owner node indicating that the non-owner node has written the new data for the first data block;

writing the new data for the first data block to the owner node, and incrementing a version associated with the first data block;

issuing a write_unlock request for the first data block to all nodes on the network; and

performing a write_unlock for the first data block on the owner node; and

wherein the second process at non-owner nodes includes;

receiving the write_lock request for the first data block from the owner node for the first data block;

performing a write_lock for the first data block, and copying old data for the first data block into memory;

writing the new data for the first data block, and incrementing a version number associated with the first data block;

sending the acknowledgment to the owner node; and

performing a write_unlock for the first data block.

9. The method of claim 8, wherein the first process at the owner node further comprises:

determining if a network error occurred prior to writing the new data for the first data block to the owner node;

writing the new data for the first data block to the owner node if a network error did not occur; and

if a network error occurred, performing corrective action.

10. The method of claim 9, wherein, if a network error occurred prior to writing the new data for the first data block to the owner node, the first process at the owner node further comprises:

determining if the owner node is active or passive after performing corrective action;

aborting the local write of the first data block to the owner node if the owner node is passive after performing corrective action; and

writing the new data for the first data block to the owner node if the owner node is active after performing the corrective action.

11. The method of claim 10, further comprising making the owner node passive after a network error if the owner node is part of a cluster of nodes that remain in communication with each other that is less than half of the nodes of a replication network before the network error.

12. The method of claim 10, wherein determining if the owner node is active or passive includes an administrator determining if the owner node is active or passive.

13. The method of claim 8, wherein the first process at the owner node further comprises:

determining if a network error occurred after writing the new data for the first data block to the owner node;

performing the write_unlock for the first data block on the owner node if a network error did not occur; and

if a network error occurred, performing corrective action.

14. The method of claim 13, wherein, if a network error occurred after writing the new data for the first data block to the owner node, the first process at the owner node further comprises determining if the owner node is active or passive after performing corrective action;

if the owner node is passive after performing corrective action, writing saved old data back to the first data block and decrementing the version number associated with the first data block; and

if the owner node is active after performing the corrective action, performing the write_unlock for the first data block on the owner node.

15. The method of claim 8, wherein the second process at the non-owner nodes further comprises:

determining if a network error occurred after writing the new data for the first data block; and

if a network error occurred, performing corrective action.

16. The method of claim 15, wherein, if a network error occurred after writing the new data for the first data block, the second process at the non-owner nodes further comprises:

determining if the owner node is active or passive after performing corrective action; and

if the owner node is passive after performing corrective action, writing saved old data back to the first data block and decrementing the version number associated with the first data block.

17. The method of claim 8, further comprising performing a third process to locally write a second data block to one of the non-owner nodes of the second data block, including:

issuing a write_lock for the second data block and copying old data for the second data block into local memory;

sending new data for the second data block to the owner node of the second data block;

if write request is received from the owner node for the second data block, writing the new data for the second data block, and incrementing a version number associated with the second data block, and performing a write_unlock for the second data block.

18. The method of claim 17, wherein the third process further comprises determining if the owner node sent competing data to write the second data block before the write request is received from the owner node, and writing the competing data to the second data block if the owner node sent competing data before the write request is received from the owner node.

19. The method of claim 17, wherein the third process further comprises:

determining if a network error occurred after writing the new data for the second data block; and

if a network error occurred, performing corrective action.

20. The method of claim 19, wherein, if a network error occurred after writing the new data for the second data block, the third process further comprises:

determining if the one of the non-owner nodes is active or passive after performing corrective action;

if the one of the non-owner nodes is passive after performing corrective action, writing saved old data back to the first data block and decrementing the version number associated with the first data block; and

if the one of the non-owner nodes is active after performing corrective action, resending the second data block to a new owner of the second data block.

21. The method of claim 19, wherein, if a network error occurred after writing the new data for the second data block, the third process further comprises performing a write_unlock if a network failure did not occur.

22. A system, comprising:

a memory storage device, including replicated storage having a plurality of data blocks stored therein and a version associated with each of the data blocks; and

a replication manager to communicate with the memory storage device, the replication manager to communicate with other network nodes in a multi-node replicated storage network through a network link interface, wherein the replication manager is adapted to;

issue read memory block commands and write memory block commands for data blocks in the replicated storage owned by the replication manager;

issue a read lock, read the data block, and release the read lock; and

issue a write lock, write the data block and increment a version associated with the data block, and release the write lock.

23. The system of claim 22, wherein the replication manager is adapted to issue a read_lock specific to the data block and issue a distributed write_lock for the network.

24. A multi-node replicated storage network, comprising:

at least two network nodes, each network node including;

a memory storage device, including replicated storage having a plurality of data blocks stored therein and a version associated with each of the data blocks;

a network link interface; and

a replication manager to communicate with other network nodes using the network link interface, and the replication manager to communicate with the memory storage device;

wherein the replication managers for the at least two network nodes are adapted to;

determine node ownership for data blocks to issue write memory block commands, each data block being owned by one node; and

write a first data block using a first process at an owner node for the first data block and using a second process at non-owner nodes.

25. The network of claim 24, wherein the first process at the owner node for the first data block includes:

issuing a write_lock request for the first data block to all nodes in the network;

copying old data for the first data block to memory, and issuing a write command to non-owner nodes in the network to write new data for the first data block;

waiting for the acknowledgment from each non-owner node indicating that the non-owner node has written the new data for the first data block;

writing the new data for the first data block to the owner node, and incrementing a version associated with the first data block;

issuing a write_unlock request for the first data block to all nodes on the network; and

performing a write_unlock for the first data block on the owner node.

26. The network of claim 25, wherein the second process at non-owner nodes for the first data block includes:

receiving the write_lock request for the first data block from the owner node for the first data block;

performing a write_lock for the first data block, and copying old data for the first data block into memory;

writing the new data for the first data block, and incrementing a version number associated with the first data block;

sending an acknowledgment to the owner node; and

performing a write_unlock for the first data block.

27. The network of claim 26, wherein:

the first process at the owner node includes;

determining if a network error occurred prior to writing the new data for the first data block to the owner node;

writing the new data for the first data block to the owner node if a network error did not occur; and

if a network error occurred, performing corrective action.

the second process at the non-owner nodes includes;

determining if a network error occurred after writing the new data for the first data block; and

if a network error occurred, performing corrective action.

28. The network of claim 24, wherein the replication managers for the at least two network nodes are adapted to locally write a second data block to non-owner nodes of the second data block using a third process, including:

issuing a write_lock for the second data block and copying old data for the second data block into local memory;

sending new data for the second data block to the owner node of the second data block; and

if write request is received from the owner node for the second data block, writing the new data for the second data block, and incrementing a version number associated with the second data block, and performing a write_unlock for the second data block.