Abstract: A method for file system reorganization in the presence of inline compression includes obtaining a virtual block pointer for an original compressed segment to be reorganized, the original compressed segment comprising compressed allocation units of data stored in a storage system, wherein the virtual block pointer comprises an extent list identifying the compressed allocation units in the original compressed segment and a pointer to where the original compressed segment is stored; copying only the referenced compressed allocation units in the original compressed segment to a new compressed segment in a substantially contiguous manner; updating the extent list to identify the referenced compressed allocation units in the new compressed segment, and the pointer to where the new compressed segment is stored; and freeing the original compressed segment.

Abstract: Techniques for limiting storage consumed by a file system without shrinking a volume upon which the file system is deployed. The techniques are employed in a clustered environment including multiple NAS nodes, each having access to block storage including multiple storage devices. By deploying the file system on a volume of a NAS node within the clustered environment, setting the value of the FS user size to be equal to the FS volume size, and if, at a later time, it is desired to reduce the file system size, setting the value of the FS user size to a lesser value than the FS volume size, IO requests received at the NAS node can be satisfied within the logical limit of the lesser value of the FS user size without shrinking the local volume, allowing the file system size to be reduced without requiring close coordination with the block storage.

Abstract: Logging changes to file system metadata using a single log hold per cached block of metadata. A metadata log including log entries is maintained in persistent storage, and each log entry in the metadata log contains metadata modified by a corresponding file system request. A single log hold is stored for each block of cached metadata. The single log hold for a given block of cached metadata indicates a file system request that modifies the metadata contained in the block, and that corresponds to a log entry located the closest, of all log entries corresponding to file system requests that modify metadata contained in the block, to a head of the metadata log.

Abstract: Techniques for limiting storage consumed by a file system without shrinking a volume upon which the file system is deployed. The techniques are employed in a clustered environment including multiple NAS nodes, each having access to block storage including multiple storage devices. By deploying the file system on a volume of a NAS node within the clustered environment, setting the value of the FS user size to be equal to the FS volume size, and if, at a later time, it is desired to reduce the file system size, setting the value of the FS user size to a lesser value than the FS volume size, IO requests received at the NAS node can be satisfied within the logical limit of the lesser value of the FS user size without shrinking the local volume, allowing the file system size to be reduced without requiring close coordination with the block storage.

Abstract: A replication process using snapshots to maintain information regarding changes made to a production data set following a point in time. In some embodiments, the production data set may be a file system and the snapshot may store information relating to changes made to both previously-allocated and newly-allocated data blocks. When a change is made to a previously-allocated data block, the original contents for the data block may be copied to a save volume prior to being overwritten by the new data, while for a newly-allocated data block no data may be copied to the save volume. An entry may also be created in a map identifying each changed data block. A replication process may then read the block map to identify data blocks storing new data to should be replicated to a replication data set, such that the replication data set remains a copy of the production data set.