Abstract: Multi-site distributed storage systems and computer-implemented methods are described for improving a resumption time of input/output (I/O) operations during a common snapshot process for storage objects. A computer-implemented method comprises performing a baseline transfer from at least one storage object of a first storage node to at least one replicated storage object of a second storage node, starting the common snapshot process including stop processing of I/O operations, performing a snapshot create operation on the primary storage site for the at least one storage object of the first storage node, resuming processing of I/O operations, and assigning a new universal unique identifier (UUID) to the at least one storage object of the second storage node after resuming processing of I/O operations with the new UUID to identify when file system contents are different than the baseline transfer.

Abstract: Multi-site distributed storage systems and computer-implemented methods are described for improving a resumption time of input/output (I/O) operations during a common snapshot procedure for storage objects. A computer-implemented method includes initiating a snap create handler operation for a storage object of a batch of storage objects having a plurality of replicated datasets with each replicated dataset having a synchronous replication relationship between at least one storage object of the first storage node and at least one replicated storage object of the second storage node, determining whether a consistency point is currently in progress or not, and providing a hint to accelerate a currently in progress consistency point when the consistency point is currently in progress.

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: In one embodiment, a method comprises maintaining state information regarding a data replication status for a storage object of the storage node of a primary storage cluster with the storage object being replicated to a replicated storage object of a secondary storage cluster, temporarily disallowing input/output (I/O) operations when the storage object has a connection loss or failure. The method further includes initiating a resynchronization between the storage object and the replicated storage object including initiating asynchronous persistent inflight tracking and replay of any missing I/O operations that are missing from one of a first Op log of the primary storage cluster and a second Op log of the secondary storage cluster, and allowing new I/O operations to be handled with the storage object of the primary storage cluster without waiting for completion of the asynchronous persistent inflight tracking and replay at the secondary storage cluster.

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: 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: In one embodiment, a method comprises maintaining state information regarding a data replication status for a storage object of the storage node of a primary storage cluster with the storage object being replicated to a replicated storage object of a secondary storage cluster, temporarily disallowing input/output (I/O) operations when the storage object has a connection loss or failure. The method further includes initiating a resynchronization between the storage object and the replicated storage object including initiating asynchronous persistent inflight tracking and replay of any missing I/O operations that are missing from one of a first Op log of the primary storage cluster and a second Op log of the secondary storage cluster, and allowing new I/O operations to be handled with the storage object of the primary storage cluster without waiting for completion of the asynchronous persistent inflight tracking and replay at the secondary storage cluster.

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 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 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 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 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: Techniques are provided for handling misaligned holes and writes beyond end of files during a quick reconciliation process. During quick reconciliation, a read operation is performed to read data from a first storage object and is replicated to a second storage object. If the data read from the first storage object comprises misaligned holes, then a different range of data is read from the first storage object so that aligned holes are read and replicated to the second storage object. If the read operation targets a region beyond an end of the first storage object, then the second storage object is truncated to a size of the first storage object.

Abstract: Techniques are provided for selectively allowing or blocking services from utilizing snapshots. A splitter intercepts and assigns timestamps to operations for execution upon files of a file system. If a snapshot is created while there are no pending operation, then the snapshot is tagged to indicate that the snapshot was created while there were no pending operations, and the snapshot is considered a tagged snapshot. Otherwise, the snapshot is not tagged, and is considered an untagged snapshot. Storage services (e.g., backup applications, lifecycle management applications, applications that consider timestamps of files, etc.) are allowed to utilize tagged snapshots and are blocked from utilizes untagged snapshots in order to maintain consistency.

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: 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 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 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: Techniques are provided for serializing replication operations. A plurality of operations are implemented upon a first storage object and are replicated as a plurality of replication operations. An order with which the plurality of replication operation are to be executed upon a second storage object is determined. Execution of the plurality of replication operations upon the second storage object is serialized according to the order.

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.