Abstract: A hybrid quorum/consensus and primary-backup fault-tolerance model in an object-based distributed data storage system. When a primary manager fails, a hierarchy of network entities is established in which a group of realm managers first authorizes a failure-handling event through quorum/consensus and a backup manager (for the failing primary manager) then executes the decision of the quorum of realm managers. The realm managers, operating by consensus, determine whether (a) the primary manager can indeed be asserted to be down, and (b) whether there is a quorum of realm managers in agreement on this decision. If both are true, a master realm manager instructs the backup manager to proceed to execute the necessary steps to become the primary manager and function as the primary until the original primary manager is brought back into service. The hybrid fault-tolerance approach handles both single unit failures and network partitions in a unified way, without creating a single cluster out of the fault domain.

Abstract: A data storage methodology wherein a hashing algorithm is applied to break a directory object experiencing frequent concurrent accesses from a number of client or manager applications into a predetermined number of hash component objects and a hash master object that manages the component objects. The hash master object and the hash components, together, constitute a hash directory, which replaces the original non-hashed directory object. Each hash component object contains a portion of the entries contained in the original directory object. Each hash component is managed by only one file manager. The entries in the original directory object are distributed among the hash component objects using a predefined hashing algorithm. The creation of hash components and the hash master allows more than one client application or file manager to concurrently write corresponding hash components without the need for access coordination on each access.

Abstract: A system and method to perform a system-wide file system image without time smear in a distributed object-based data storage system. A realm manager is elected as an image master using the Distributed Consensus Algorithm to execute image-taking. All pending write capabilities are invalidated prior to taking the system-wide file system image so as to quiesce the realm and prepare the storage system for the system-wide image. Once the system is quiesced, the image master instructs each storage manager in the system to clone each live object group contained therein without explicitly cloning any objects contained in such object group. In one embodiment, a file manager copies an object in the system before a write operation is performed on that object after the image is taken. Neither the cloning operation nor the copying operation update any directory objects in the system. At run time, a client application may use a mapping scheme to access objects contained in the system-wide image.

Abstract: A hybrid quorum/consensus and primary-backup fault-tolerance model in an object-based distributed data storage system. When a primary manager fails, a hierarchy of network entities is established in which a group of realm managers first authorizes a failure-handling event through quorum/consensus and a backup manager (for the failing primary manager) then executes the decision of the quorum of realm managers. The realm managers, operating by consensus, determine whether (a) the primary manager can indeed be asserted to be down, and (b) whether there is a quorum of realm managers in agreement on this decision. If both are true, a master realm manager instructs the backup manager to proceed to execute the necessary steps to become the primary manager and function as the primary until the original primary manager is brought back into service. The hybrid fault-tolerance approach handles both single unit failures and network partitions in a unified way, without creating a single cluster out of the fault domain.

Abstract: A system and method to perform a system-wide file system image without time smear in a distributed object-based data storage system. A realm manager is elected as an image master using the Distributed Consensus Algorithm to execute image-taking. All pending write capabilities are invalidated prior to taking the system-wide file system image so as to quiesce the realm and prepare the storage system for the system-wide image. Once the system is quiesced, the image master instructs each storage manager in the system to clone each live object group contained therein without explicitly cloning any objects contained in such object group. In one embodiment, a file manager copies an object in the system before a write operation is performed on that object after the image is taken. Neither the cloning operation nor the copying operation update any directory objects in the system. At run time, a client application may use a mapping scheme to access objects contained in the system-wide image.

Abstract: A data storage methodology wherein a hashing algorithm is applied to break a directory object experiencing frequent concurrent accesses from a number of client or manager applications into a predetermined number of hash component objects and a hash master object that manages the component objects. The hash master object and the hash components, together, constitute a hash directory, which replaces the original non-hashed directory object. Each hash component object contains a portion of the entries contained in the original directory object. Each hash component is managed by only one file manager. The entries in the original directory object are distributed among the hash component objects using a predefined hashing algorithm. The creation of hash components and the hash master allows more than one client application or file manager to concurrently write corresponding hash components without the need for access coordination on each access.