Abstract: Tools and techniques for determining conditions of conferences are described herein. These tools may provide machine-readable storage media that contain machine-readable instructions that, when executed by the machine, cause the machine to calculate a global conference parameter that represents a rate at which several different conferences are processed. The machine may also calculate individual conference parameters representing a duration of time spent in processing the conferences considered individually.

Abstract: Internally, a production file system and each of its related snapshot file systems have a common file system identifier (fid?) and a unique respective file system identifier (fsid?). Externally, the production file system and each of its related snapshot file systems has a common file system identifier (fsid) and a unique respective file identifier (fid). For example, the “fsid” and “fid” for the production and snapshot file systems are interchanged between a client-server protocol layer and a logical volume layer in a file server. Moreover, the file handle for an object indicates whether an object is in either a production file system that is not configured to have related snapshots, a production file system that is configured to have related snapshots, or a snapshot file system. When the object is in a snapshot file system, the file handle also indicates the related production file system.

Abstract: Accordingly a method and interface allows an attribute data base used by an Information Manager to be quickly populated and accurately maintained. A single Bulk Attribute Retrieval Request triggers the primary storage device to collect object attribute information. The method allows for selective collection of objects and attributes by providing filters and attribute lists in the Requests. The Request may be used to provide an incremental scan with appropriate time stamp filtering. In addition, the size of the results can be controlled by the IM by eliminating attributes that are not of interest to the IM. The Request is advantageously issued over a FileMover interface, which is an HTTP connection, and encoded in XML, allowing the IM to easily customize the Request as desired.

Abstract: Consistency errors may arise during replication of diverse data storage objects from servers in a data network. For preventing consistency errors, a server is programmed for responding to a request for a report of whether or not the server can replicate the dataset without causing a consistency error. Such a report is useful for replicating a consistency group of objects from more than one server. Preparation for replication can be begun at each of the servers, and if any of the servers fail to report that replication can be done without causing a consistency error, the preparation can be aborted so that write access by applications will not be disrupted while the potential problem is diagnosed and eliminated.

Abstract: Metadata management in a file server or storage network is delegated from a primary data processor to a secondary data processor in order to reduce data traffic between the primary data processor and the secondary data processor. The primary data processor retains responsibility for managing locks upon objects in the file system that it owns, and also retains responsibility for allocation of free blocks and inodes of the file system. By leasing free blocks and inodes to the secondary and granting locks to the secondary, the secondary can perform the other metadata management tasks such as appending blocks to a file, truncating a file, creating a file, and deleting a file.

Abstract: In a network attached cached disk storage system, data is transmitted over the network in data packets having a data length that is much smaller than the logical block size for reading or writing to disk storage. To avoid copying of data from network port buffers to the cache memory, the cache blocks of the cache memory are organized as linked lists of list elements, which can be used as network port input or output buffers. For TCP data packets, for example, each list element has a data slot for storing up to 1,500 bytes, and a field indicating the number of bytes stored in the data slot.

Abstract: Read-only and read-write snapshot copies of a production file in a Unix-based file system are organized as a version set of file inodes and shared file blocks. Version pointers and branch pointers link the inodes. Initially the production file can have all its blocks preallocated or it can be a sparse file having only an inode and its last data block. A protocol is provided for creating read-only and read-write snapshots, deleting snapshots, restoring the production file with a specified snapshot, refreshing a specified snapshot, and naming the snapshots. Block pointers are marked with a flag indicating whether or not the pointed-to block is owned by the parent inode. A non-owner marking is inherited by all of the block's descendants. The block ownership controls the copying of indirect blocks when writing to the production file, and also controls deallocation and passing of blocks when deleting a read-only snapshot.

Abstract: A write interface in a file server provides permission management for concurrent access to data blocks of a file, ensures correct use and update of indirect blocks in a tree of the file, preallocates file blocks when the file is extended, solves access conflicts for concurrent reads and writes to the same block, and permits the use of pipelined processors. For example, a write operation includes obtaining a per file allocation mutex (mutually exclusive lock), preallocating a metadata block, releasing the allocation mutex, issuing an asynchronous write request for writing to the file, waiting for the asynchronous write request to complete, obtaining the allocation mutex, committing the preallocated metadata block, and releasing the allocation mutex. Since no locks are held during the writing of data to the on-disk storage and this data write takes the majority of the time, the method enhances concurrency while maintaining data integrity.

Abstract: To avoid the need for storing a tree quota identifier attribute for every file in a quota tree, a tree quota identifier is included in the file handle returned by the file server to a client in response to a directory lookup request. The file server discovers that the file is in a quota tree when searching along a path specified by the file pathname and finding a directory having a tree quota identifier. The file server responds to a client request for changing the storage resources used by the file by inspecting the file handle and upon finding the tree quota identifier in the file handle, using the tree quota identifier to index a tree quota database to find usage and limits for the tree quota. The file server checks the limits against any increase in the storage resources for the file, and updates the usage.

Abstract: A storage object such as a virtual disk drive or a raw logical volume is contained in a UNIX compatible file so that the file containing the storage object can be exported using the NFS or CIFS protocol and shared among UNIX and MS Windows clients or servers. The storage object can be replicated and backed up using conventional file replication and backup facilities without disruption of client access to the storage object. For client access to data of the storage object, a software driver accesses the file containing the storage object. For example, a software driver called a virtual SCSI termination is used to access a file containing a virtual SCSI disk drive. Standard storage services use the iSCSI protocol to access the virtual SCSI termination. An IP replication or snapshot copy facility may access the file containing the virtual SCSI disk drive using a higher-level protocol.

Abstract: In a network attached cached disk storage system, data is transmitted over the network in data packets having a data length that is much smaller than the logical block size for reading or writing to disk storage. To avoid copying of data from network port buffers to the cache memory, the cache blocks of the cache memory are organized as linked lists of list elements, which can be used as network port input or output buffers. For TCP data packets, for example, each list element has a data slot for storing up to 1,500 bytes, and a field indicating the number of bytes stored in the data slot.

Abstract: Internally, a production file system and each of its related snapshot file systems have a common file system identifier (fid′) and a unique respective file system identifier (fsid′). Externally, the production file system and each of its related snapshot file systems has a common file system identifier (fsid) and a unique respective file identifier (fid). For example, the “fsid” and “fid” for the production and snapshot file systems are interchanged between a client-server protocol layer and a logical volume layer in a file server. Moreover, the file handle for an object indicates whether an object is in either a production file system that is not configured to have related snapshots, a production file system that is configured to have related snapshots, or a snapshot file system. When the object is in a snapshot file system, the file handle also indicates the related production file system.

Abstract: Metadata management in a file server or storage network is delegated from a primary data processor to a secondary data processor in order to reduce data traffic between the primary data processor and the secondary data processor. The primary data processor retains responsibility for managing locks upon objects in the file system that it owns, and also retains responsibility for allocation of free blocks and inodes of the file system. By leasing free blocks and inodes to the secondary and granting locks to the secondary, the secondary can perform the other metadata management tasks such as appending blocks to a file, truncating a file, creating a file, and deleting a file.

Abstract: A file server provides transaction processing capabilities previously supplied by the operating system of a host computer. On-disk file system metadata is changed only at commit time, and a transaction log protects the transition. The disk state can only be a consistent state, resulting from a commit operation. All disk-block reservation and pre-allocation mapping are in the memory, and after a crash, they are automatically discarded. The file server therefore relieves the client of processing burden and also reduces network traffic. In addition, the file server can more efficiently perform the transaction processing capabilities and reduce the frequency of access to storage by judicious allocation of file system blocks and transfer of file system blocks between file system objects, cache memory, and the transaction log. The differentiation between preallocation states and allocation states of in-memory file system blocks also permits application programs to more efficiently transfer data between files.