Abstract:
Systems, apparatuses, methods, and computer-readable storage mediums for performing lease-based fencing using a time-limited lease window. During the time-limited lease window, writes to a shared storage medium are permitted, while writes are denied for expired leases. When a successful heartbeat is generated for a primary storage controller, the lease window is extended for the primary storage controller from the time of a previous heartbeat. Accordingly, a prolonged stall between successive heartbeats by the primary storage controller will result in the newly extended lease being expired at the time it is granted. This scheme prevents a split brain scenario from occurring when a secondary storage controller takes over as the new primary storage controller in response to detecting the stall.
Abstract:
Preventing duplicate entries of identical data in a storage device, including: receiving a write request to write data to the storage device; calculating one or more signatures for the data associated with the write request; determining whether any of the calculated signatures match a calculated signature contained in a recently read signature buffer, each entry in the recently read signature buffer associating a calculated signature for data that has been read with an address of a storage location within the storage device where the data is stored; and responsive to determining that one of the calculated signatures matches a calculated signature contained in the recently read signature buffer, determining whether the data associated with the calculated signature is a duplicate of data stored at a particular address that is associated with the calculated signature contained in the recently read signature buffer.
Abstract:
Systems, methods, and computer readable storage mediums for optimistically managing compressed data in a storage system. When possible, multiple input blocks are compressed into a buffer and stored in a single physical block on a storage device. The metadata of the multiple input blocks can be managed separately. A fingerprint of the compressed buffer can be generated and used as an index to the single physical block. Alternatively, fingerprints of the uncompressed input blocks can be generated, and reference counts can be maintained to track the number of input blocks which reference the compressed buffer.
Abstract:
Preventing duplicate entries of identical data in a storage device, including: receiving a write request to write data to the storage device; calculating one or more signatures for the data associated with the write request; determining whether any of the calculated signatures match a calculated signature contained in a recently read signature buffer, each entry in the recently read signature buffer associating a calculated signature for data that has been read with an address of a storage location within the storage device where the data is stored; and responsive to determining that one of the calculated signatures matches a calculated signature contained in the recently read signature buffer, determining whether the data associated with the calculated signature is a duplicate of data stored at a particular address that is associated with the calculated signature contained in the recently read signature buffer.
Abstract:
Preventing duplicate entries of identical data in a storage device, including: receiving a write request to write data to the storage device; calculating one or more signatures for the data associated with the write request; determining whether any of the calculated signatures match a calculated signature contained in a recently read signature buffer, each entry in the recently read signature buffer associating a calculated signature for data that has been read with an address of a storage location within the storage device where the data is stored; and responsive to determining that one of the calculated signatures matches a calculated signature contained in the recently read signature buffer, determining whether the data associated with the calculated signature is a duplicate of data stored at a particular address that is associated with the calculated signature contained in the recently read signature buffer.
Abstract:
Systems, apparatuses, methods, and computer-readable storage mediums for performing lease-based fencing using a time-limited lease window. During the time-limited lease window, writes to a shared storage medium are permitted, while writes are denied for expired leases. When a successful heartbeat is generated for a primary storage controller, the lease window is extended for the primary storage controller from the time of a previous heartbeat. Accordingly, a prolonged stall between successive heartbeats by the primary storage controller will result in the newly extended lease being expired at the time it is granted. This scheme prevents a split brain scenario from occurring when a secondary storage controller takes over as the new primary storage controller in response to detecting the stall.