Abstract: Techniques are provided for resynchronizing a synchronous replication relationship. Asynchronous incremental transfers are performed to replicate data of a storage object to a replicated storage object. Incoming write requests, targeting the storage object, are logged into a dirty region log during a last asynchronous incremental transfer. Metadata operations, executed on the storage object, are logged into a metadata log during the last asynchronous incremental transfer. Sequence numbers are assigned to the metadata operations based upon an order of execution. The metadata operations are replicated to the replicated storage object for execution according to the sequence numbers, and the dirty regions are replicated to the replicated storage object in response to the metadata operations having been replicated to the replicated storage object.

Abstract: Techniques are provided for persistent hole reservation. For example, hole reservation flags of operations targeting a first storage object of a first node are replicated into replication operations targeting a second storage object of a second node during a transition operation to transition the first storage object and the second storage object from an asynchronous replication state to a synchronous replication state. In another example, the second storage object is grown to a size of a replication punch hole operation that failed due to targeting a file block number greater than an end of size of the second storage object.

Abstract: Techniques are provided for dependency aware parallel splitting of operations. For example, a count of pending data operations being executed by a first node and replicated in parallel to a second node are tracked. A metadata operation is executed at the first node based upon the count being less than a threshold (e.g., the count being zero). A first list of affected inodes modified by the metadata operation is identified. A dependency of the metadata operation with respect to pending metadata operations replicated to the second node is determined. The metadata operation is dispatched to the second node based upon the dependency indicating that the metadata operation is independent of the pending metadata operations.

Abstract: In one embodiment, a method comprises maintaining state information regarding a data synchronous replication status for a storage object of a primary storage cluster and a replicated storage object of a secondary storage cluster. The method includes temporarily disallowing input/output (I/O) operations for the storage object when the storage object of the primary storage cluster has a failure, which causes an internal state as out of sync for the storage object while maintaining an external state as in sync for external entities. The method performs persistent inflight tracking and reconciliation of I/O operations with a first Op log of the primary storage cluster and a second Op log of the secondary storage cluster and performs a resynchronization between the storage object and the replicated storage object based on the persistent inflight tracking and reconciliation of I/O operations.

Abstract: Systems and methods are described for performing persistent inflight tracking of operations (Ops) within a cross-site storage solution. According to one embodiment, a method comprises maintaining state information regarding a data synchronous replication status for a first storage object of a primary storage cluster and a second storage object of a secondary storage cluster. The state information facilitates automatic triggering of resynchronization for data replication between the first storage object and the second storage object. The method includes performing persistent inflight tracking of I/O operations with a first Op log of the primary storage cluster and a second Op log of the secondary storage cluster, establishing and comparing Op ranges for the first and second Op logs, and determining a relation between the Op range of the first Op log and the Op range of the second Op log to prevent divergence of Ops in the first and second Op logs and to support parallel split of the Ops.

Abstract: Techniques are provided for resynchronizing a synchronous replication relationship. Asynchronous incremental transfers are performed to replicate data of a storage object to a replicated storage object. Incoming write requests, targeting the storage object, are logged into a dirty region log during a last asynchronous incremental transfer. Metadata operations, executed on the storage object, are logged into a metadata log during the last asynchronous incremental transfer. Sequence numbers are assigned to the metadata operations based upon an order of execution. The metadata operations are replicated to the replicated storage object for execution according to the sequence numbers, and the dirty regions are replicated to the replicated storage object in response to the metadata operations having been replicated to the replicated storage object.

Abstract: Techniques are provided for resynchronizing a synchronous replication relationship. Asynchronous incremental transfers are performed to replicate data of a storage object to a replicated storage object. Incoming write requests, targeting the storage object, are logged into a dirty region log during a last asynchronous incremental transfer. Metadata operations, executed on the storage object, are logged into a metadata log during the last asynchronous incremental transfer. Sequence numbers are assigned to the metadata operations based upon an order of execution. The metadata operations are replicated to the replicated storage object for execution according to the sequence numbers, and the dirty regions are replicated to the replicated storage object in response to the metadata operations having been replicated to the replicated storage object.

Abstract: Techniques are provided for persistent hole reservation. For example, hole reservation flags of operations targeting a first storage object of a first node are replicated into replication operations targeting a second storage object of a second node during a transition operation to transition the first storage object and the second storage object from an asynchronous replication state to a synchronous replication state. In another example, the second storage object is grown to a size of a replication punch hole operation that failed due to targeting a file block number greater than an end of size of the second storage object.

Abstract: Techniques are provided for replay of metadata and data operations. During initial execution of operations, identifiers of objects modified by the execution of each operation are identified and stored in association with the operations. When the operations are to be replayed (e.g., executed again, such as part of a replication operation or as part of flushing content from a cache to persistent storage), the identifiers are evaluated to determine which operations are independent with respect to one another and which operations are dependent with respect to one another. In this way, independent operations are executed in parallel and dependent operations are executed serially with respect to the operations from the dependent operations depend.

Abstract: Techniques are provided for maintaining timestamp parity during a transition replay phase to a synchronous state. During a transition logging phase where metadata operations executed by a primary node are logged into a metadata log and regions modified by data operations executed by the primary node are tracked within a dirty region log, a close stream operation to close a stream associated with a basefile of the primary node is identified. A determination is made as to whether the dirty region log comprises an entry for the stream indicating that a write data operation previously modified the stream. In an example, in response to the dirty region log comprising the entry, an indicator is set to specify that the stream was deleted by the close stream operation. In another example, a modify timestamp of the basefile is logged into the metadata log for subsequent replication to the secondary node.

Abstract: Techniques are provided for replay of metadata and data operations. During initial execution of operations, identifiers of objects modified by the execution of each operation are identified and stored in association with the operations. When the operations are to be replayed (e.g., executed again, such as part of a replication operation or as part of flushing content from a cache to persistent storage), the identifiers are evaluated to determine which operations are independent with respect to one another and which operations are dependent with respect to one another. In this way, independent operations are executed in parallel and dependent operations are executed serially with respect to the operations from the dependent operations depend.

Abstract: Techniques are provided for maintaining timestamp parity during a transition replay phase to a synchronous state. During a transition logging phase where metadata operations executed by a primary node are logged into a metadata log and regions modified by data operations executed by the primary node are tracked within a dirty region log, a close stream operation to close a stream associated with a basefile of the primary node is identified. A determination is made as to whether the dirty region log comprises an entry for the stream indicating that a write data operation previously modified the stream. In an example, in response to the dirty region log comprising the entry, an indicator is set to specify that the stream was deleted by the close stream operation. In another example, a modify timestamp of the basefile is logged into the metadata log for subsequent replication to the secondary node.

Abstract: Techniques are provided for inofile management and access control list file handle parity. For example, operations targeting a first storage object of a first node are replicated to a second storage object of a second node. A size of an inofile maintained by the second node is increased if an inode number to be allocated by the replication operation is greater than a current size of the inofile. Access control list file handle parity is achieved by maintaining parity between inode number and generation number pairings of the first node and the second node.

Abstract: Techniques are provided for timestamp consistency. An operation targeting a first storage object having a synchronous replication relationship with a second storage object is intercepted. A timestamp is assigned to the operation. A replication operation is created as a replication of the operation. The same timestamp is assigned to the replication operation. The operation is implemented upon the first storage object and the replication operation is implemented upon the second storage object.

Abstract: Techniques are provided for dependency aware parallel splitting of operations. For example, a first operation and a second operation may be replicated in parallel from a first device to a second device if the operations only target a single common inode that is an access control list inode referenced by the operations. An operation that dereferences the access control list inode can be replicated in parallel with other operations if the operation does not have the potential to delete the access control list inode from the second device. In another example, operations may be replicated to the second device in parallel if the operations only affect a single common parent directory inode and where timestamps are only moved forward in time at the second device.

Abstract: A request is received to retrieve at least a portion of a file from a compressed data archived image stored in a backup storage device. The compressed data archived image comprises a backup of a file system having a number of directories and a number of files. The compressed data archived image comprises a file that includes a compression of the number of files. An address of the at least the portion of the file within the compressed data archived image is determined. The at least the portion of the file is retrieved at the address in the compressed data archived image, without decompressing the compressed data archived image.

Abstract: Techniques are provided for freeing and utilizing unused inodes. For example, an operation, targeting a first storage object of a first node having a replication relationship with a second storage object of a second node, is intercepted. A replication operation is created as a replication of the operation. The operation is implemented upon the first storage object and the replication operation is implemented upon the second storage object. A determination is made that the replication operation uses an inode no longer used by storage objects of the second node. The inode targeted by the replication operation is freed and utilized based upon the inode being a leaf inode. If the inode is a stream directory inode, then data streams of the stream directory inode are moved under a new private inode and the stream directory inode is released.

Abstract: Techniques are provided for inofile management and access control list file handle parity. For example, operations targeting a first storage object of a first node are replicated to a second storage object of a second node. A size of an inofile maintained by the second node is increased if an inode number to be allocated by the replication operation is greater than a current size of the inofile. Access control list file handle parity is achieved by maintaining parity between inode number and generation number pairings of the first node and the second node.

Abstract: Techniques are provided for timestamp consistency. An operation targeting a first storage object having a synchronous replication relationship with a second storage object is intercepted. A timestamp is assigned to the operation. A replication operation is created as a replication of the operation. The same timestamp is assigned to the replication operation. The operation is implemented upon the first storage object and the replication operation is implemented upon the second storage object.

Abstract: Techniques are provided for dependency aware parallel splitting of operations. For example, a first operation and a second operation may be replicated in parallel from a first device to a second device if the operations only target a single common inode that is an access control list inode referenced by the operations. An operation that dereferences the access control list inode can be replicated in parallel with other operations if the operation does not have the potential to delete the access control list inode from the second device. In another example, operations may be replicated to the second device in parallel if the operations only affect a single common parent directory inode and where timestamps are only moved forward in time at the second device.