US 7,734,733 B1Granted

WAFS disconnected-mode read-write access

AssigneePacketeer, Inc.

InventorsHrishikesh A. Vidwans, Suresh Gopalakrishnan, Shirish H. Phatak, Murali Rangarajan

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Abstract

The present invention, in particular embodiments, provides methods, apparatuses and systems directed to providing a Wide Area File System that is robust against network connectivity issues. In particular implementations, the present invention provides a WAFS disconnected-mode read-write access that provides for a more seamless user experience against WAN or other network connectivity failures. Specific embodiments provide for management, at a network device such as an EFG node, of file objects previously opened during a connected state with a remote file server appliance, creation of new file objects during a disconnected state and re-synchronization of those file objects (data and meta-data) when a connection becomes available.

Claims20

Dependent claims

An apparatus comprising

a memory,
one or more network interfaces,
one or more processors;
and
logic encoded in one or more computer readable media, the logic comprising computer executable instructions operative to cause the one or more processors to implement:
a connection state machine operative to
monitor connectivity to one or more remote file server cache nodes;
maintain state indications of the connectivity to one or more remote file server cache nodes;
a wide area file system module operative to
emulate a file server to one or more client nodes;
access, responsive to requests of the one or more client nodes, file objects and obtain corresponding leases from one or more remote file server cache nodes;
store the file objects received from the one or more remote file server cache nodes in a local cache for access by the one or more client nodes;
maintain a mapping of file objects stored in a local cache to corresponding remote file server cache nodes;
forward requests for file system operations from the one or more client nodes to corresponding remote file server cache nodes;
wherein the wide area file system module is further operative to:
responsive to a loss of connectivity to a first remote file server cache node,
perform file system operations requested by the one or more client nodes locally in the local cache;
track the file system operations in one or more data structures;
and
responsive to regaining connectivity to the first remote file server cache node, synchronize the file system operations tracked in the one or more data structures with the first remote file server cache node.

17 more elements

A method for use in a network device operative to process requests, pertaining to remotely-stored file objects, between a local user and a remote file server appliance operative to retrieve and store the remotely-stored file objects, the network device further operative to request and maintain write-leases on one or more of the remotely-stored file objects, the method comprising:

detecting a connectivity loss to the remote file server appliance;
transitioning from a connected state to an un-connected state upon detection of the connectivity loss;
while in the un-connected state:
creating a committed object list (“COL”) based on file objects with open write leases;
initializing an un-committed object list (“UOL”);
receiving a file object command;
and
selectively adding or removing a file object entry to the COL or UOL based on the received command and write lease status of the associated file object;
detecting restoration of connectivity to the remote file server appliance;
transitioning from the un-connected state to a re-integration state upon detection of the restoration;
while in the re-integration state:
processing entries in the COL and UOL;
and
transitioning to the connected state once the COL and UOL entries have been processed.

11 more elements

A network device operative to process requests, pertaining to remotely-stored file objects, between a local user and a remote file server appliance operative to retrieve and store the remotely-stored file objects, the network device further operative to request and maintain write-leases on one or more of the remotely-stored file objects, the network device comprising:

one or more network interfaces;
one or more processors;
a memory;
an WAN connection state machine, stored in the memory, including instructions operable to cause the one or more processors and the network device to:
detect a connectivity loss to the remote file server appliance;
transition from a connected state to art un-connected state upon detection of the connectivity loss;
while in the un-connected state:
create a committed object list (“COL”) based on file objects with open write leases;
initialize an un-committed object list (“UOL”);
receive a file object command;
and
selectively add or remove a file object entry to the COL or UOL based on the received command and write lease status of the associated file object;
detecting restoration of connectivity to the remote file server appliance;
transition from the un-connected state to a re-integration state upon detection of the restoration;
while in the re-integration state:
process entries in the COL and UOL;
and
transition to the connected state once the COL and UOL entries have been processed.

15 more elements

Dependencies are inferred from the claim text.