On Demand File Virtualization for Server Configuration Management with Limited Interruption

1 . In a storage network having one or more storage servers and having a distributed file system (DFS) server that exports a global namespace consisting of file objects exported by the storage servers in the storage network, and wherein clients of the storage network always consult the DFS server for the identification of a storage server that exports an unknown file object before accessing, and wherein clients of the storage network may choose to access a known file object directly from its storage server without consulting the DFS server for its accuracy, a method of inserting a file virtualization appliance for maintaining consistency of the namespace during namespace reconfiguration, the method comprising:

configuring a global namespace of the virtualization appliance to match a global namespace exported by the distributed filesystem server; and

updating the distributed filesystem server to redirect client requests associated with the global namespace to the virtualization appliance.

2 . A method according to claim 1 , further comprising:

after updating the distributed filesystem server, ensuring that no clients are directly accessing the file servers; and

thereafter sending an administrative alert to indicate that insertion of the virtualization appliance is complete.

3 . A method according to claim 2 , wherein ensuring that no clients are directly accessing the file servers comprises:

identifying active client sessions running on the file servers; and

ensuring that the active client sessions include only active client sessions associated with the virtualization appliance.

4 . A method according to claim 3 , wherein the virtualization appliance is associated with a plurality of IP addresses, and wherein ensuring that the active client sessions include only active client sessions associated with the virtualization appliance comprises ensuring that the active client sessions include only active client sessions associated with any or all of the plurality of IP addresses.

5 . A method according to claim 2 , wherein ensuring that no clients are directly accessing the file servers comprises:

sending a session close command to a file server in order to terminate an active client session unrelated to the virtualization appliance.

6 . A method according to claim 2 , wherein ensuring that no clients are directly accessing the file servers comprises:

monitoring activity associated with active client sessions; and

sending an administrative alert presenting an administrator with an option to close the active client sessions.

7 . A method according to claim 2 , wherein ensuring that no clients are directly accessing the file servers comprises:

sending an alert to a client associated with an active client session requesting that the client close the active client session.

8 . A method according to claim 2 , further comprising:

automatically reconfiguring a switch to create a VLAN for the virtualization appliance.

9 . A method according to claim 1 , wherein the distributed filesystem server is configured to follow the Distributed File System standard.

10 . A method according to claim 1 , wherein connecting a virtualization appliance to the storage network includes:

connecting a first switch to a second switch, wherein the first switch is connected to at least one file server;

connecting the virtualization appliance to the first switch;

connecting the virtualization appliance to the second switch; and

for each file server connected the first switch, disconnecting the file server from the first switch and connecting the file server to the second switch.

11 . A method for removing a virtualization appliance logically positioned between client devices and file servers in a storage network having a distributed filesystem server, the method comprising:

sending a global namespace from the virtualization appliance to the distributed filesystem server; and

configuring the virtualization appliance to not respond to any new client connection requests received by the virtualization appliance.

12 . A method according to claim 11 , further comprising:

disconnecting the virtualization appliance from the storage network after a predetermined final timeout period.

13 . A method according to claim 11 , further comprising:

for any client request associated with an active client session received by the virtualization appliance during a predetermined time window, closing the client session.

14 . A method according to claim 13 , wherein the predetermined time window is between the end of a first timeout period and the predetermined final timeout period.

15 . A method according to claim 11 , wherein the distributed filesystem server is configured to follow the Distributed File System standard.