Method and apparatus for transparent distributed network-attached storage with web cache communication protocol/anycast and file handle redundancy

• US 7,254,636 B1
• Filed: 03/14/2003
• Issued: 08/07/2007
• Est. Priority Date: 03/14/2003
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: O'Toole, James W. Jr., Bornstein, David M.
• Primary Examiner(s): Najjar; Saleh
• Assistant Examiner(s): Bates; Kevin T
• Application Number:
  US10/388,785
• Time in Patent Office: 1,607 Days
• Field of Search: 709/203, 709/217, 709/228, 709/230, 707/8, 707/10
• US Class Current: 709/230
• CPC Class Codes: G06F 16/10 File systems; File servers
• CPC Class Codes: Y10S 707/99938 Concurrency, e.g. lock management in shared database

Abstract

A distributed network-attached storage network provides content distribution using conventional file transfer protocols such as NFS and CIFS. A filer proxy accepts a client request and translates the client request to a file transfer protocol accepted at the file system having the file requested in the client request. The filer proxy generates a file handle for the file containing redundant filer proxy information to be used for failover to a backup filer proxy in the event of a network error or failure of an original filer proxy. The file handle also contains information for network security purposes such as detection of forged file handles.

Claims

1. In a first filer proxy, a method for handling a client request, comprising the steps of:

peering with a router in a computer network to provide a path directed to a filesystem attached to said computer network, said filesystem having a network address;

receiving a client request from a client for a file in said filesystem, said client request including said network address;

determining in response to said client request an accepted file transfer protocol for said network address; and

forwarding said client request using said accepted file transfer protocol to a destination based on said network address;

wherein said determining step further comprises the steps of;

determining a client request file transfer protocol of said client request; and

determining a requester identity;

wherein the method further comprises the step of;

creating a file handle to represent an open file opened in response to said client request, said file handle including said client request file transfer protocol and said requestor identity;

wherein creating the file handle further comprises;

including within the file handle an object identification number temporarily assigned to the file opened in response to said client request;

including within the file handle a network location of the file opened in response to said client request, the network location of the file identifying the location within the computer network where the file is stored;

including within the file handle a first filer proxy identification number and a second filer proxy identification number, the first filer proxy identification number identifying the first filer proxy, and the second filer proxy identification number identifying a second filer proxy;

including within the file handle a generation count of the file opened in response to said client request;

including within the file handle a verifying code; and

including within the file handle a client identification number.

2. The method of claim 1 wherein said peering step further comprises advertising to a router in said computer network that the first filer proxy is a low-cost route to said filesystem.

3. The method of claim 1 wherein said peering step further comprises instructing a router in said computer network, using Web Cache Communication Protocol, to forward requests for said filesystem to the first filer proxy.

4. The method of claim 3 wherein said router is part of a service group of routers in said computer network and said instructing step further comprises the steps of:

sending notification to a service group address which provides information to all routers in said service group, said notification including router configuration for said routers in said service group and filer proxy configuration for the first filer proxy;

receiving from said routers in said service group a list of filer proxy addresses configured in said service group; and

,

providing a policy to said service group for routers in said service group to follow in redirecting data packets in said computer network.

5. The method of claim 1 wherein said path is directed to an anycast address for a range of network addresses.

6. The method of claim 1 wherein said path is directed to an anycast address for a partition group connected to said computer network.

7. The method of claim 1 wherein said filesystem is part of a network-attached storage system.

8. The method of claim 1 wherein said determining step further comprises looking up said accepted file transfer protocol in a table of network addresses and associated file transfer protocols.

9. The method of claim 1 wherein said determining step further comprises looking up said accepted file transfer protocol in table of mount points with associated file protocols.

10. The method of claim 1 further comprising the step of determining, before forwarding said client request to said network address, whether said client request should be handled by a second filer proxy and if so, forwarding said client request to said second filer proxy instead of to said network address.

11. The method of claim 10 further comprising the step of forwarding said client request to a second filer proxy if said network address is not found in a table of addresses in the first filer proxy.

12. The method of claim 1 further comprising the steps of:

maintaining in a table said file handle associated with a connection control state for said open file; and

forwarding said file handle to said client to use for operations on said open file.

13. The method of claim 12 wherein said file handle further includes a hash count, said client identification number and said hash count for verifying said file handle.

14. The method of claim 12 wherein said file handle includes an i-node of said file.

15. The method of claim 12 wherein said file handle further includes a mount point of said file and a hash count for verifying said file handle.

16. The method of claim 1 further comprising the step of holding a lock on a file opened in response to said client request, to enable concurrent usage of the file among clients.

17. The method of claim 16 further comprising storing said file lock in association with a file handle of the file.

18. The method of claim 1, further comprising the steps of:

synchronizing a file opened in response to said client request by determining if changes have been made to the file since a prior synchronization; and

if changes have been made to the file since said prior synchronization, replacing said file with a new file incorporating said changes.

19. The method of claim 1, further comprising the steps of:

in the second filer proxy,

after the first filer proxy fails to respond to a second client request for an operation on said file, receiving said second client request, said second client request including said file handle;

reading information from said file handle; and

acting on said second client request in response to said information.

20. The method of claim 19, further comprising the steps of:

in said second filer proxy,

detecting that the first filer proxy is operational; and

,

forwarding said second client request to the first filer proxy.

21. The method of claim 19, further comprising the steps of:

in said second filer proxy,

detecting that the first filer proxy is operational;

requesting in response to said second file request, a file handle entry from the first filer proxy; and

receiving from the first filer proxy said file handle entry.

22. The method of claim 21, wherein said file handle entry includes a lock state and compressed file differences for said file.

23. The method of claim 19, wherein the step of acting on said second request further comprises the steps of:

in the second filer proxy,

detecting that the first filer proxy is inoperational;

determining whether the second file request is a read operation, and

if so, proceeding with a read operation on said file.

24. The method of claim 19, wherein the step of acting on said second request, further comprising the steps of:

in the second filer proxy,

detecting that the first filer proxy is inoperational;

determining whether said second file request is a write operation; and

if so, then determining whether said file has file locks;

if so, then taking ownership of said file locks; and

proceeding with said write operation.

25. The method of claim 24 further comprising the steps of:

in the first filer proxy,

duplicating file lock information into said file handle; and

in said second filer proxy,

said step of determining file locks further comprises the step of reading said file lock information from said file handle.

26. The method of claim 24, further comprising the steps of:

in the first filer proxy,

duplicating file lock information into a backup table at a master filer;

and

in the second filer proxy,

reading said file lock information from said master filer backup table.

27. The method of claim 24, wherein said step of determining file locks per client further comprises the step of:

in the first filer proxy,

duplicating file lock information for said client into a backup table at a master controller;

and

in the second filer proxy,

reading said file lock information from said master controller backup table.

28. The method of claim 24, wherein said step of determining file locks per proxy per partition group further comprises the steps of:

in the first filer proxy,

duplicating file lock information in said file handle; and

in the master filer,

making a file handle/control state entry for said open file for a second filer proxy.

29. The method of claim 1, further comprising the steps of:

in the second filer proxy,

after the first filer proxy fails to respond to a second client request for an operation on said file, receiving said second client request, said second client request including said file handle;

generating an error message; and

forwarding said error message to the client.

30. A filer proxy, comprising:

at least one communications interface for receiving a client request and for transmitting data in response to said client request;

a protocol stack connected to said at least one communications interface, said protocol stack to determine an accepted file transfer protocol at a filesystem specified in said client request;

a file operation controller connected to said protocol stack to forward said client request to said filesystem in said accepted file transfer protocol through said at least one communications interface; and

a file handle and connection state table connected to said file operation controller, said file handle and connection state table to hold a file handle of an open file opened in response to said client request in association with a connection state of said open file;

wherein the file handle includes;

an object identification number temporarily assigned to the file opened in response to said client request;

a network location of the file opened in response to said client request, the network location of the file identifying the location within the computer network where the file is stored;

a first filer proxy identification number and a second filer proxy identification number, the first filer proxy identification number identifying the filer proxy, and the second filer proxy identification number identifying a second filer proxy;

a generation count of the file opened in response to said client request;

a verifying code; and

a client identification number.

31. The filer proxy of claim 30, wherein said protocol stack further comprises:

at least one file transfer protocol module to determine an incoming file transfer protocol of said client request, to determine said accepted file transfer protocol, and to translate said client request to a format of said accepted file transfer protocol.

32. The filer proxy of claim 31, wherein said protocol stack further comprises:

a Network File System module to determine whether said client request is in Network File System format and to translate said client request to Network File System format if said filesystem accepts data in Network File System format; and

a Common Internet File System module to determine whether said client request is in Common Internet File System format and to translate said client request to Common Internet File System format if said filesystem accepts data in Common Internet File System format.

33. The filer proxy of claim 30, wherein the protocol stack further comprises:

a table of filesystem addresses and associated accepted file transfer protocols for said protocol stack to use to determine said accepted file transfer protocol for said filesystem specified in said client request.

34. The filer proxy of claim 30, further comprising:

a lock and concurrency controller connected to said file operation controller and said file handle and connection state table to control operations to said open file and to maintain concurrency of said open file with said file in said filesystem.

35. The filer proxy of claim 30, further comprising:

a redundancy/dispatch logic module to determine whether said received client request should be handled in the filer proxy and to forward said client request to the second filer proxy if not.

36. The filer proxy of claim 30, further comprising:

a file cache controller connected to said file operation controller, said file cache controller to control caching of said open file in a local storage module connected to the filer proxy.

37. The filer proxy of claim 36, further comprising:

a file synchronizer logic module connected to said file cache controller and to a lock and concurrency controller, said file synchronizer logic module to take inputs from said file cache controller and said lock and concurrency controller to synchronize said open file to said file in said filesystem.

38. A master filer, comprising:

a memory; and

a controller coupled to said memory, said controller configured to;

manage filesystems attached to a computer network,

manage filer proxies attached to said computer network, and

manage open files from said filesystems,

the master filer to receive a client request forwarded from a filer proxy, the client request transferred to the master filer in a file transfer protocol, the master filer to open a requested file and to provide information to said filer proxy with which to generate a file handle containing redundant proxy information, the file transfer protocol being determined by the filer proxy;

wherein the file handle includes;

an object identification number temporarily assigned to the requested file;

a network location of the requested file, the network location of the file identifying the location within the computer network where the file is stored;

a first filer proxy identification number and a second filer proxy identification number;

a generation count of the requested file;

a verifying code; and

a client identification number.

39. The master filer of claim 38 further comprising a local cache coupled to the master filer.

40. The master filer of claim 38 further comprising a table of mount points and associated filesystems.

41. The master filer of claim 38 further comprising a table of filer proxies and supported mount points.

42. The master filer of claim 38 further comprising a table of locked files and associated file handles.

43. A distributed network-attached storage network, comprising:

at least one network-attached storage system attached to the network;

a master filer attached to the network, the master filer to manage said at least one network-attached storage system;

a first filer proxy attached to the network, said first filer proxy to translate a client request to a file protocol accepted by a filesystem in said at least one network-attached storage system said file system to generate with said master filer a file handle for a file opened in response to said client request, the file handle having redundant file proxying information; and

a second filer proxy attached to said network, said second filer proxy capable of proxying said file using said redundant file proxying information in said file handle in the event that said first filer proxy is unable to continue proxying said file;

wherein the file handle includes;

an object identification number temporarily assigned to the file opened in response to said client request;

a network location of the file opened in response to said client request, the network location of the file identifying the location within the computer network where the file is stored;

a first filer proxy identification number and a second filer proxy identification number, the first filer proxy identification number identifying the first filer proxy, and the second filer proxy identification number identifying the second filer proxy;

a generation count of the file opened in response to said client request;

a verifying code; and

a client identification number.

44. A computer program product having a computer-readable medium including computer program logic encoded thereon that, when performed on a computer system directs the computer system to perform the method of:

providing a path to a first filer proxy through a computer network, said path directed to a filesystem attached to said computer network, said filesystem having a network address;

receiving a client request from a client for a file in said filesystem, said client request including said network address;

determining in response to said client request an accepted file transfer protocol for said network address; and

forwarding said client request using said accepted file transfer protocol to a destination based on said network address;

wherein said determining step further comprises the steps of;

determining a client request file transfer protocol of said client request; and

determining a requester identity;

wherein the method performed on the computer system further comprises the step of;

creating a file handle to represent an open file opened in response to said client request, said file handle including said client request file transfer protocol and said requester identity;

wherein creating the file handle further comprises;

including within the file handle an object identification number temporarily assigned to the file opened in response to said client request;

including within the file handle a network location of the file opened in response to said client request, the network location of the file identifying the location within the computer network where the file is stored;

including within the file handle a first filer proxy identification number and a second filer proxy identification number, the first filer proxy identification number identifying the first filer proxy, and the second filer proxy identification number identifying a second filer proxy;

including within the file handle a generation count of the file opened in response to said client request;

including within the file handle a verifying code; and

including within the file handle a client identification number.