Abstract: A system and method are disclosed for providing data transfer between a source machine and a target machine. In one embodiment of the present invention, a method and system for transferring data comprises performing a first operation wherein the first operation copies a first file from a first memory to a second memory, and a second file from the first memory to the second memory, wherein the first file is copied substantially concurrently with the copying of the second file, and wherein the first operation results in a first copied file and a second copied file in the second memory; and performing a second operation wherein the second operation updates the first copied file and the second copied file in a predetermined order.

Abstract: A computer network remote data mirroring system writes update data both to a local data device and to a local, chronologically sequenced journal storage area, or writelog device. A graphical user interface enables a user to create and configure throttles, which are user-defined tests and actions evaluated by the primary mirror daemon to regulate network bandwidth, CPU, and writelog device utilization during data update mirroring. Network bandwidth throttling enables a predetermined portion of the network bandwidth to be assigned to remote data mirroring based on user-selected criteria. CPU throttling enables a user to control the amount of time the local data storage unit will wait prior to returning control to applications after an update. Writelog device throttling prevents a memory overflow condition by dynamically assigning memory to the writelog device by chaining writelog device extensions to the writelog device.

Abstract: A method and system for mirroring and archiving mass storage. A primary mass storage and a secondary mass storage are synchronized to contain the same data. Thereafter, a primary system tracks changes made to the primary mass storage. These changes are consolidated periodically into update files, the consolidations representing changes made to the primary mass storage during a time interval that ends when the primary mass storage is in a logically consistent state. These update files contain only those changes necessary to represent the modified state of the primary mass storage at the time of the update. The primary system then transfers the update files to a secondary system to bring the secondary mass storage current with the primary mass storage. The consolidation minimizes the amount of information that must be transferred and therefore allows for a relatively low band width communication channel.

Abstract: A method for providing rapid recovery from a network file server failure through the use of a backup computer system. The backup computer system runs a special mass storage access program that communicates with a mass storage emulator program on the network file server, making the disks or other mass storage devices on the backup computer system appear like they were disks on the file server computer. By mirroring data by writing to both the mass storage of the file server and through the mass storage emulator and mass storage access program to the disks on the backup computer, a copy of the data on the file server computer is made. Optionally, selected portions of the data read through the mass storage emulator program can be altered before being returned as the result of the read operation on the file server. In the event of failure of the file server computer, the backup computer can replace the file server, using the copy of the file server's data stored on its disks.

Abstract: Obtaining mirrored data so that the original data can be recovered after failure without transmitting the entire mirrored data between computers. A write request at a primary computer is stored in a delay buffer and a copy is transmitted to a backup computer, where it is stored in a delta queue. The backup computer executes the copy of the write request to the mirrored data and transmits an acknowledgement to the primary computer that the copy of the write request has been received. In response to the acknowledgement, the primary computer executes the write request stored in the delay buffer. The computers send to each other subsequent acknowledgements of the write request execution, enabling the computers to delete the write requests. If the primary computer fails, the primary computer can recover the original data by receiving only the copies of write requests that remain stored in the delta queue.

Abstract: A computer network remote data mirroring system writes update data both to a local data device and to a local, chronologically sequenced journal storage area, or writelog device. A primary mirror daemon on a local computer system monitors the writelog device for data updates and feeds the data over a network in the same order in which it is stored to a receiving remote mirror daemon on a remote computer system, which in turn commits the data updates to a mirror device. A graphical user interface enables a user to create and configure throttles. Throttles are user-defined tests and actions evaluated by the primary mirror daemon to regulate network bandwidth, CPU, and writelog device utilization during data update mirroring. Network bandwidth throttling enables a predetermined portion of the network bandwidth to be assigned to remote data mirroring based on user-selected criteria.

Abstract: A method and system for mirroring and archiving mass storage. A primary mass storage and a secondary mass storage are synchronized to contain the same data. Thereafter, a primary system tracks changes made to the primary mass storage. These changes are consolidated periodically into update files, the consolidations representing changes made to the primary mass storage during a time interval that ends when the primary mass storage is in a logically consistent state. These update files contain only those changes necessary to represent the modified state of the primary mass storage at the time of the update. The primary system then transfers the update files to a secondary system to bring the secondary mass storage current with the primary mass storage. The consolidation minimizes the amount of information that must be transferred and therefore allows for a relatively low band width communication channel.

Abstract: A primary computer system and a backup computer system each have an associated memory. For each write request, a copy of the request is forwarded to a delay buffer and memory queue associated with the primary computer system, and a copy is forwarded to a memory queue of the backup computer system. The backup computer system transmits an acknowledgement signal to the primary computer system when the backup computer system receives its copy of the request. The write request in the delay buffer of the primary computer system is executed in the primary memory only upon receipt of this acknowledgement signal. Thus, the backup computer system knows of every request executed in the primary memory. The write request is executed in the backup memory at any time after the backup computer system receives the write request.

Abstract: A computer network remote data mirroring system writes update data both to a local data device and to a local, chronologically sequenced journal storage area, or writelog device. If the local computer system crashes, upon recovery or re-boot of the local computer system, the two most current updates in the writelog device are written to the local data device to assure that the data stored on the local data device is current. Additional memory or disk space is dynamically assigned to the writelog device to prevent a memory overflow condition. The computer network remote data mirroring system can be structured to provide logical groups of local data device/writelog device pairs. A primary mirror daemon on a local computer system monitors the writelog device for data updates and feeds the data over a network in the same order in which it is stored to a receiving remote mirror daemon on a remote computer system, which in turn commits the data updates to a mirror device.

Abstract: A system and method for providing substantially concurrent mirroring of files across a network. A data file is selected for mirroring on a local computer system and one or more remote computer systems are designated to store a back-up copy of the selected data file. As changes to the selected data file occur, change information is captured by a mirroring driver, which is attached to the file system driver, and then forwarded from the local computer system across the network to the remote computer system or systems. Each remote computer system then updates the back-up copy of the data file.

Abstract: A method and apparatus for a server fail-over system is provided. The fail-over system includes a plurality of servers for providing a plurality of services. Each server may provide more than one service. The plurality of servers includes a first server for providing a first service, the system further including a client for consuming the plurality of services, including the first service. A network connects the client to the plurality of servers. If the first server fails to provide the first service, the first service fails over to a second server of the plurality of servers, the second server of the plurality of servers being the highest priority server for providing the first service in the event of failure of the first server.

Abstract: An acceleration device for enhancing the speed of synchronous writes in a computer system includes a novel control subsystem, in one embodiment a device driver, and stable storage having an access time on the same order of magnitude as the access time of the main memory in the computer system. In one embodiment, the novel device driver is interposed in the operating system of the computer between the proprietary kernel and one or more peripheral storage unit device drivers. The novel device driver intercepts I/O commands, for example, synchronous write commands, from the operating system that are intended for one of the peripheral storage unit device drivers and subsequently copies the data specified in the write command from main memory of the computer to the stable storage of the acceleration device. The stable storage is operated as a cache and upon one of a set of predetermined conditions being satisfied, selected data stored in the stable storage are transferred, i.e.

Abstract: An acceleration device for enhancing the speed of synchronous writes in a computer system includes a novel control means, in one embodiment a device driver, and stable storage having an access time on the same order of magnitude as the access time of the main memory in the computer system. In one embodiment, the novel device driver is interposed in the operating system of the computer between the proprietary kernel and one or more peripheral storage unit device drivers. The novel device driver intercepts I/O commands, for example, synchronous write commands, from the operating system that are intended for one of the peripheral storage unit device drivers and subsequently copies the data specified in the write command from main memory of the computer to the stable storage of the acceleration device. The stable storage is operated as a cache and upon one of a set of predetermined conditions being satisfied, selected data stored in the stable storage are transferred, i.e.