Abstract: A method and apparatus for reconstructing lost data from a failed disk drive in a disk array. The disk drive array formed into at least one parity group including data extents divided into data segments and parity segments that are generated from the data segments. The method includes providing access to the array, identifying a failed drive and failed parity group associated with the failed drive, and retrieving the parity segments from operative drives in a parity group containing the failed drive in an instance data is being read from the failed parity group. Parity information is reconstructed for the failed disk drive from the parity segments on the operative disk drives, and data segments of the extent associated with the failed disk drive is reconstructed from the reconstructed parity information, and the parity segments and data segments on the operative disk drives of the failed parity group.

Abstract: A queuing architecture and method for scheduling disk drive access requests in a video server. The queuing architecture employs a controlled admission policy that determines how a new user is assigned to a specific disk drive in a disk drive array. The queuing architecture includes, for each disk drive, a first queue for requests from users currently receiving information from the server, and a second queue for all other disk access requests, as well as a queue selector selecting a particular first queue or second queue for enqueuing a request based on the controlled admission policy. The controlled admission policy defines a critical time period such that if a new user request can be fulfilled without causing a steady-state access request for a particular disk drive to miss a time deadline, the new user request is enqueued in the second queue of the particular disk drive; otherwise, the controlled admission policy enqueues the new user request in a second queue of another disk drive.

Abstract: A method for streaming content striped in RAID 5 format from an array of disk drives to subscribers to minimize disruptive service from a disk drive failure. The method includes accessing content data on an extent-by-extent basis from a plurality of disk drives in an array and streams the content data to the subscribers on an extent-by-extent basis, sequentially, from the plurality of disk drives. Upon detection of an actual disk drive failure the method transitions to a stream regeneration mode of operation, which includes reading the content data substantially simultaneously from all extents in a parity group and regenerating a failed portion of the content data from a failed extent in the parity group corresponding to the failed disk drive. The content data in the parity group is streamed to the subscribers, extent-by-extent, immediately following the regenerating of the content data from the failed extent in the parity group.

Abstract: A method and apparatus for recovering data from a failed disk drive in a disk drive array. The method and apparatus includes storing data on an array of disk drives by dividing extents of data into data segments and defining a parity group including at least one data segment from a plurality of data segments from different extents. Parity segments are generated from the data segments in the parity group and stored in the parity group. Furthermore, a second parity segment is generated from the parity segments and storied with the parity group. The method and apparatus then outputs data in realtime to users in a normal disk access mode from parity groups without the failed disk drive, and outputs recovered data in realtime to the users in a parity correction mode from the parity group containing the failed disk drive.

Abstract: A queuing architecture and method for scheduling disk drive access requests in a video server. The queuing architecture employs a controlled admission policy that determines how a new user is assigned to a specific disk drive in a disk drive array. The queuing architecture includes, for each disk drive, a first queue for requests from users currently receiving information from the server, and a second queue for all other disk access requests, as well as a queue selector selecting a particular first queue or second queue for enqueuing a request based on the controlled admission policy. The controlled admission policy defines a critical time period such that if a new user request can be fulfilled without causing a steady-state access request for a particular disk drive to miss a time deadline, the new user request is enqueued in the second queue of the particular disk drive; otherwise, the controlled admission policy enqueues the new user request in a second queue of another disk drive.

Abstract: A queuing architecture and method for scheduling disk drive access requests in a video server. The queuing architecture employs a controlled admission policy that determines how a new user is assigned to a specific disk drive in a disk drive array. The queuing architecture includes, for each disk drive, a first queue for requests from users currently receiving information from the server, and a second queue for all other disk access requests, as well as a queue selector selecting a particular first queue or second queue for enqueuing a request based on the controlled admission policy. The controlled admission policy defines a critical time period such that if a new user request can be fulfilled without causing a steady-state access request for a particular disk drive to miss a time deadline, the new user request is enqueued in the second queue of the particular disk drive; otherwise, the controlled admission policy enqueues the new user request in a second queue of another disk drive.

Abstract: A method and apparatus for recovering data from a failed disk drive in a disk drive array. The method and apparatus includes storing data on an array of disk drives by dividing extents of data into data segments and defining a parity group including at least one data segment from a plurality of data segments from different extents. Parity segments are generated from the data segments in the parity group and stored in the parity group. Furthermore, a second parity segment is generated from the parity segments and storied with the parity group. The method and apparatus then outputs data in realtime to users in a normal disk access mode from parity groups without the failed disk drive, and outputs recovered data in realtime to the users in a parity correction mode from the parity group containing the failed disk drive.

Abstract: A method for streaming content striped in RAID 5 format from an array of disk drives to subscribers to minimize disruptive service from a disk drive failure. The method includes accessing content data on an extent-by-extent basis from a plurality of disk drives in an array and streams the content data to the subscribers on an extent-by-extent basis, sequentially, from the plurality of disk drives. Upon detection of an actual disk drive failure the method transitions to a stream regeneration mode of operation, which includes reading the content data substantially simultaneously from all extents in a parity group and regenerating a failed portion of the content data from a failed extent in the parity group corresponding to the failed disk drive. The content data in the parity group is streamed to the subscribers, extent-by-extent, immediately following the regenerating of the content data from the failed extent in the parity group.

Abstract: A queuing architecture and method for scheduling disk drive access requests in a video server. The queuing architecture employs a controlled admission policy that determines how a new user is assigned to a specific disk drive in a disk drive array.

Abstract: A method of accessing an array of storage devices comprising the steps of analyzing a data request from a user to determine the optimal storage device from which data should be retrieved, assigning the user to a first group of users that will access the optimal storage device in a first time period, retrieving data to fulfill the data request from the optimal storage device, and buffering the data in a buffer. Thereafter, the method assigns the user to a second group of users that will be supplied data from the buffer in a second time period, and then retrieving the data from the buffer and transmitting the data to the user to fulfill the data request.