Abstract:
A low-overhead merge technique enables restart of a merge operation with minimal logging of state information relating to progress of the merge operation by a volume layer of a storage input/output (I/O) stack executing on one or more nodes of a cluster. The technique enables restart of the merge operation by ensuring that metadata, i.e., metadata pages, generated during the merge operation is not subject to de-duplication by providing a unique value in each metadata page that distinguishes the page, i.e., renders the page distinct or “unique”, from other metadata pages in an extent store. In addition, the technique ensures that a reference count on each metadata page is a value denoting a lack of de-duplication. To that end, the extent store layer is configured to not increment the reference count for a metadata page if, during the merge operation, the page is identical (and thus subject to deduplication) to an existing metadata page in the extent store.
Abstract:
A low-overhead merge technique enables restart of a merge operation with minimal logging of state information relating to progress of the merge operation by a volume layer of a storage input/output (I/O) stack executing on one or more nodes of a cluster. The technique enables restart of the merge operation by ensuring that metadata, i.e., metadata pages, generated during the merge operation is not subject to de-duplication by providing a unique value in each metadata page that distinguishes the page, i.e., renders the page distinct or “unique”, from other metadata pages in an extent store. In addition, the technique ensures that a reference count on each metadata page is a value denoting a lack of de-duplication. To that end, the extent store layer is configured to not increment the reference count for a metadata page if, during the merge operation, the page is identical (and thus subject to deduplication) to an existing metadata page in the extent store.
Abstract:
One or more techniques and/or computing devices are provided for cross-platform replication. For example, a replication relationship may be established between a first storage endpoint and a second storage endpoint, where at least one of the storage endpoints, such as the first storage endpoint, lacks or has incompatible functionality to perform and manage replication because the storage endpoints have different storage platforms that store data differently, use different control operations and interfaces, etc. Accordingly, replication destination workflow, replication source workflow, and/or a proxy representing the first storage endpoint may be implemented at the second storage endpoint comprising the replication functionality. In this way, replication, such as snapshot replication, may be implemented between the storage endpoints by the second storage endpoint using the replication destination workflow, the replication source workflow, and/or the proxy that either locally executes tasks or routes tasks to the first storage endpoint such as for data access.
Abstract:
A N-way merge technique efficiently updates metadata in accordance with a N-way merge operation managed by a volume layer of a storage input/output (I/O) stack executing on one or more nodes of a cluster. The metadata is embodied as mappings from logical block addresses (LBAs) of a logical unit (LUN) accessible by a host to durable extent keys, and is organized as a multi-level dense tree. The mappings are organized such that a higher level of the dense tree contains more recent mappings than a next lower level, i.e., the level immediately below. The N-way merge operation is an efficient (i.e., optimized) way of updating the volume metadata mappings of the dense tree by merging the mapping content of all three levels in a single iteration, as opposed to merging the content of the first level with the content of the second level in a first iteration of a two-way merge operation and then merging the results of the first iteration with the content of the third level in a second iteration of the operation.