Abstract: Method and apparatus for locating data on disk storage, wherein multiple instances of data can be stored at different locations to satisfy different use requirements such as read access, write access, and data security. The method allows a data storage system, such as a file system, to provide both read optimized and write optimized performance on disk storage of different types (e.g., sizes and speed).

Abstract: Allocation process that allows erasure coded data to be stored on any of a plurality of disk drives, in a pool of drives, so that the allocation is not tied to a fixed group of drives. Still further, the encoded data can be generated by any of multiple different erasure coding algorithms, where again storage of the encoded data is not restricted to a single group of drives based on the erasure algorithm being utilized to encode the data. In another embodiment, the encoded data can be “stacked” (aligned) on select drives to reduce the number of head seeks required to access the data. As a result of these improvements, the system can dynamically determine which one of multiple erasure coding algorithms to utilize for a given incoming data block, without being tied to one particular algorithm and one particular group of storage devices as in the prior art.

Abstract: Allocation process that allows erasure coded data to be stored on any of a plurality of disk drives, in a pool of drives, so that the allocation is not tied to a fixed group of drives. Still further, the encoded data can be generated by any of multiple different erasure coding algorithms, where again storage of the encoded data is not restricted to a single group of drives based on the erasure algorithm being utilized to encode the data. In another embodiment, the encoded data can be “stacked” (aligned) on select drives to reduce the number of head seeks required to access the data. As a result of these improvements, the system can dynamically determine which one of multiple erasure coding algorithms to utilize for a given incoming data block, without being tied to one particular algorithm and one particular group of storage devices as in the prior art.

Abstract: Method and apparatus for locating data on disk storage, wherein multiple instances of data can be stored at different locations to satisfy different use requirements such as read access, write access, and data security. The method allows a data storage system, such as a file system, to provide both read optimized and write optimized performance on disk storage of different types (e.g., sizes and speed).

Abstract: Described is a technique for asynchronous event notification in a data storage system. Lower level software, such as a device driver or other software application generating events, reports the occurrence of an event to an event handler. The event handler implements an event reporting policy which may include event consolidation. The event handler reports the events to an event dispatcher which notifies event subscribers of the occurrence of events in accordance with registration information of each subscriber. The event handler may execute in kernel mode or user mode depending on the particular execution mode of lower level software initially reporting the occurrence of events. There may be a hierarchical arrangement of multiple event dispatchers in connection with event reporting. Event dispatchers may implement data sharing of registration information.