COHERENT STORAGE NETWORK

• US 20110231615A1
• Filed: 12/29/2010
• Published: 09/22/2011
• Est. Priority Date: 03/19/2010
• Status: Active Grant

• Current Assignee: NetApp, Inc.
• Original Assignee: NetApp, Inc.
• Inventors: Ober, Robert E.
• Granted Patent: US 8,868,846 B2
• Time in Patent Office: Days
• US Class Current: 711/142
• CPC Class Codes: G06F 12/0868 Data transfer between cache memory and other subsystems, e.g. storage devices or host systems
• CPC Class Codes: G06F 2212/264 Remote server
• CPC Class Codes: H04L 49/90 Buffering arrangements
• CPC Class Codes: H04L 49/9073 Early interruption upon arrival of a fraction of a packet
• CPC Class Codes: H04L 67/1097 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]
• CPC Class Codes: H04L 67/289 Intermediate processing functionally located close to the data consumer application, e.g. in same machine, in same home or in same sub-network
• CPC Class Codes: H04L 67/568 Storing data temporarily at an intermediate stage, e.g. caching

Abstract

Disclosed is a coherent storage system. A network interface device (NIC) receives network storage commands from a host. The NIC may cache the data to/from the storage commands in a solid-state disk. The NIC may respond to future network storage command by supplying the data from the solid-state disk rather than initiating a network transaction. Other NIC'"'"'s on other hosts may also cache network storage data. These NICs may respond to transactions from the first NIC by supplying data, or changing the state of data in their caches.

Claims

1. A method of maintaining storage data coherency across a network, comprising:

receiving, from a first host, a first read from network storage command associated with a first block of data;

in response to the first read from network storage command, determining whether said first block of data requested by said first read from network storage command is cached by a second host;

in response to determining said first block of data is cached by said second host, causing said second host to write said first block of data; and

,

receiving at said first host, said first block of data.

3. The method of claim 1, wherein said second host writes said first block of data to a storage server holding a copy of said first block of data.

4. The method of claim 1, wherein said second host writes said first block of data to said first host.

5. The method of claim 1, further comprising:

storing a master copy of said first data block in a storage server adapted to receive, from said first host, said first read from network storage command associated with said first block of data.

6. The method of claim 1, further comprising:

updating a master copy of said first data block in a storage server adapted to receive, from said second host, said first block of data written by said second host.

7. The method of claim 1, wherein determining whether said first block of data requested by said first read from network storage command is cached by said second host uses a MESI protocol.

8. A method of maintaining storage data coherency across a storage area network, comprising:

receiving, from a first host, at a master storage server, via said storage area network, a first request to change a first MESI state of a block of data;

sending, to a second host, by the master storage server, via said storage area network, a second request that causes the second host to change a second MESI of said block of data in a cache associated with said second host; and

,

supplying, to said first host, by said master storage server, via said storage area network, said block of data and a third MESI state associated with said block of data.

9. The method of claim 8, further comprising:

sending, to a second host, by the master storage server, via said storage area network, a third request that causes the second host to send a second block of data in said cache associated with said second host to said master storage server.

10. A coherent network interface device, comprising:

a first interface configured to receive a first block storage command from a host, said first block storage command associated with a first data block;

a second interface configured to send said first block storage command to a master storage server via a network, and to receive said first data block data and a first MESI state associated with said first data block from said storage server;

a cache memory controller configured to store said first data block data and said first MESI state a cache memory and to retrieve said first data block data from said cache memory in response to a second block storage command and said first MESI state.

11. The network interface device of claim 10, wherein said second interface is configured to send iSCSI commands.

12. The network interface device of claim 10, wherein said second interface is configured to send fiber channel (FC) commands.

13. The network interface device of claim 10, wherein said second interface is configured to send fiber channel over Ethernet (FCoE) commands.

14. The network interface device of claim 10, wherein said first interface is configured to receive PCI commands and said second interface is configured to send block storage commands over an internet protocol (IP) network.

15. The network interface device of claim 10, wherein said cache memory controller is further configured to overwrite said first MESI state in said cache memory in response to a command from said master storage server.