Abstract: A system, method and computer readable medium for providing a standby file system with snapshot feature is disclosed. A first snapshot of a primary file system is generated. Next, a standby file system restores the first snapshot of the primary file system in the standby file system and a snapshot of the standby file system is taken. Then, a second snapshot of the primary file system is taken and a data set capturing the differences between the first snapshot of the primary file system and a previous data set of the primary file system is generated. Subsequently, the data set is applied to the standby file system. Upon unavailability of the primary file system, the standby file system is initialized as the new primary file system. Upon recovery of the old primary file system, the old primary file system is initialized as a new standby file system.

Abstract: Concurrent access to data is managed through concurrency control techniques. Various types of techniques are employed to manage the access, including locking-based techniques and non-locking-based techniques. A dynamic switch from one type of concurrency control technique (e.g., a locking-based technique) to a different type of concurrency control technique (e.g., a non-locking-based technique) is enabled. This switching is based on access patterns and/or application requirements for each file. The switching allows enhanced performance for both coarse-grain sharing and fine-grain sharing of data.

Abstract: A system, method and computer readable medium for providing a standby file system with snapshot feature is disclosed. A first snapshot of a primary file system is generated. Next, a standby file system restores the first snapshot of the primary file system in the standby file system and a snapshot of the standby file system is taken. Then, a second snapshot of the primary file system is taken and a data set capturing the differences between the first snapshot of the primary file system and a previous data set of the primary file system is generated. Subsequently, the data set is applied to the standby file system. Upon unavailability of the primary file system, the standby file system is initialized as the new primary file system. Upon recovery of the old primary file system, the old primary file system is initialized as a new standby file system.

Abstract: One or more conflicting tokens are revoked using a revocation capability that eliminates the need for the holders of the conflicting tokens to communicate with the token server. Instead, information used to revoke the one or more conflicting tokens is provided by the token holders to a requester of a token that is in conflict with the conflicting tokens. The requester then forwards this information to the token server in a message already being sent to the server. Thus, additional messages between the requester and the token server are not needed.

Abstract: Asynchronous messages are used to prefetch and/or relinquish tokens used in providing locking of shared resources. A message is sent to prefetch one or more tokens, and prior to receiving a reply for the message, another message (e.g., an acquire) is sent for at least one of those tokens. Similarly, a message is sent indicating a voluntary relinquish of one or more tokens and without having acknowledgment that the relinquish request was processed, a further message (e.g., an acquire) is sent for at least one of the tokens. Multiple tokens may be acquired and/or relinquished in a single message to the token server. This reduces message delays and overall message traffic.

Abstract: The amount of memory being utilized to store token state information is monitored. In response to the monitoring, one or more actions are taken. For instance, if the monitoring indicates that too much memory is being used to store token state information, then one or more actions are performed to reclaim memory and/or obtain additional memory elsewhere. These actions may include informing one or more clients to reduce their cache sizes, thereby relinquishing tokens; reducing or eliminating one or more byte range token trees; and/or migrating the token server from one node to another node. If the monitoring indicates that additional memory can be used for storing token state information, then one or more client nodes are informed that their cache sizes can be increased.

Abstract: A computer system manages files shared by first and second heterogeneous clients. The first client exhibits a first protocol such as SMB and the second client exhibits a second, different protocol such as NFS. A first protocol converter receives requests from the first client to create, read and update the files, and converts the requests to corresponding requests exhibiting a common protocol. A second protocol converter receives requests from the second client to create, read and update the files, and converts the requests to corresponding requests exhibiting the common protocol. A file manager is common to both clients and both protocol converters, receives the converted requests exhibiting the common protocol and executes the requests in a name space and data area which are both common to the first and second clients. The name space stores names of the files and the data area stores the files.

Abstract: An editing system for use in a virtual machine environment in which two virtual machines having corresponding virtual storage areas are operatively related to one another. The editing system allows a first virtual machine to print, display, modify and otherwise control and process information stored in a second virtual machine storage area.