Abstract: A method for a file server to support snapshots in a storage area network (SAN) providing a plurality of clients with concurrent direct I/O access to a file system in the SAN, in which the SAN uses an access protocol for file system access. The method includes operating the file server to: start to maintain, at a time T1, a time T1 snapshot volume of a live volume of data in the file system; receive, from a client C1 at a time subsequent to T1, an update access request for a portion of a file that includes data stored in access unit B1 of the live volume subsequent to time T1; and responsive to the update access request, allocate, to the time T1 snapshot volume, a new access unit B2 corresponding to access unit B1, and copy data stored in access unit B1 to access unit B2.

Abstract: A method for storing updatable user data using a cluster of application servers includes: storing updateable user data across a plurality of the application servers, wherein each application server manages an associated local storage device on which resides a local file system for storage of the user data and for metadata pertaining thereto; receiving a point-in-time copy (PTC) request from a client; freezing the local file systems of the plurality of clustered application servers; creating a PTC of the metadata of each frozen local file system; and unfreezing the local file systems of the plurality of clustered application servers.

Abstract: A method for a file server to support snapshots in a storage area network (SAN) providing a plurality of clients with concurrent direct I/O access to a file system in the SAN, in which the SAN uses an access protocol for file system access. The method includes operating the file server to: start to maintain, at a time T1, a time T1 snapshot volume of a live volume of data in the file system; receive, from a client C1 at a time subsequent to T1, an update access request for a portion of a file that includes data stored in access unit B1 of the live volume subsequent to time T1; and responsive to the update access request, allocate, to the time T1 snapshot volume, a new access unit B2 corresponding to access unit B1, and copy data stored in access unit B1 to access unit B2.