Abstract: Techniques are provided for storage tier verification checks. A determination is made that a mount operation of an aggregate of a set of volumes stored within a multi-tier storage environment has completed. A first metafile and a second metafile are maintained to track information related to the storage of objects of a volume of the aggregate within a remote object store that is a tier of the multi-tier storage environment. A distributed verification is performed between the first metafile and the second metafile to identify an inconsistency. Accordingly, the first metafile and the second metafile are reconciled to address the inconsistency so that storage information within the first metafile and the second metafile are consistent.

Abstract: Methods and systems for co-locating journaling and data storage are provided. Separate journal and volume partitions may be maintained within each logical storage unit (e.g., Logical Unit Number (LUN)) of a distributed storage system. Journaling of metadata associated with write requests received from one or more clients may be distributed by identifying a destination logical storage unit to which data associated with a given write request is to be stored and causing the data and metadata to be persisted to disk by journaling the metadata and the data to respective portions of an active log within the journal partition of the destination logical storage unit. By using the same logical storage unit for both journaling of write requests and writing the data associated with such write requests, the bottleneck due to there being only a single device or storage unit handling all metadata for all write requests can be avoided.

Abstract: Techniques are provided for multi-tier write allocation. A storage system may store data within a multi-tier storage environment comprising a first storage tier (e.g., storage devices maintained by the storage system), a second storage tier (e.g., a remote object store provided by a third party storage provider), and/or other storage tiers. A determination is made that data (e.g., data of a write request received by the storage system) is to be stored within the second storage tier. The data is stored into a staging area of the first storage tier. A second storage tier location identifier, for referencing the data according to a format utilized by the second storage tier, is assigned to the data and provided to a file system hosting the data. The data is then destaged from the staging area into the second storage tier, such as within an object stored within the remote object store.

Abstract: Systems and methods for performing a zero-copy volume move between nodes of a distributed storage system are provided. In one example, an approach for performing a zero-copy volume move is proposed in which volume data may be maintained in place within a storage pod and need not be copied to move a given volume between the source node and the destination node. In one embodiment, metadata (e.g., a top-most physical volume block number (PVBN) of a node tree representing the volume at issue) of a write-anywhere file system is copied from the source node to the destination node. Since the storage pod is associated with a global PVBN space that is visible and accessible to all nodes of the distributed storage system, as a result of copying the top-mode PVBN of the volume to the destination node, anything below the top-most PVBN will automatically be visible to the destination node.

Abstract: Techniques are provided for failing over an aggregate from one file system instance to a different file system instance of a distributed scale-out storage system. The aggregate may be stored within distributed storage that is accessible to a plurality of file system instances of the distributed scale-out storage system. When the aggregate is failed over from a first file system instance to a second file system instance, the first file system instance may still have a valid read lease that allows the first file system instance to serve client I/O, directed to the aggregate, using a cache. In order to prevent the first file system instance from serving stale data from the cache before the read lease expires, state machines and a set of control data are used to ensure that the second file system instance attaches to the aggregate only after the read lease has expired.

Abstract: Techniques are provided for multi-tier write allocation. A storage system may store data within a multi-tier storage environment comprising a first storage tier (e.g., storage devices maintained by the storage system), a second storage tier (e.g., a remote object store provided by a third party storage provider), and/or other storage tiers. A determination is made that data (e.g., data of a write request received by the storage system) is to be stored within the second storage tier. The data is stored into a staging area of the first storage tier. A second storage tier location identifier, for referencing the data according to a format utilized by the second storage tier, is assigned to the data and provided to a file system hosting the data. The data is then destaged from the staging area into the second storage tier, such as within an object stored within the remote object store.

Abstract: Techniques are provided for storage tier verification checks. A determination is made that a mount operation of an aggregate of a set of volumes stored within a multi-tier storage environment has completed. A first metafile and a second metafile are maintained to track information related to the storage of objects of a volume of the aggregate within a remote object store that is a tier of the multi-tier storage environment. A distributed verification is performed between the first metafile and the second metafile to identify an inconsistency. Accordingly, the first metafile and the second metafile are reconciled to address the inconsistency so that storage information within the first metafile and the second metafile are consistent.

Abstract: Techniques are provided for journal replay optimization. A distributed storage architecture can implement a journal within memory for logging write operations into log records. Latency of executing the write operations is improved because the write operations can be responded back to clients as complete once logged within the journal without having to store the data to higher latency disk storage. If there is a failure, then a replay process is performed to replay the write operations logged within the journal in order to bring a file system up-to-date. The time to complete the replay of the write operations is significantly reduced by caching metadata (e.g., indirect blocks, checksums, buftree identifiers, file block numbers, and consistency point counts) directly into log records. Replay can quickly access this metadata for replaying the write operations because the metadata does not need to be retrieved from the higher latency disk storage into memory.

Abstract: Techniques are provided for failing over an aggregate from one file system instance to a different file system instance of a distributed scale-out storage system. The aggregate may be stored within distributed storage that is accessible to a plurality of file system instances of the distributed scale-out storage system. When the aggregate is failed over from a first file system instance to a second file system instance, the first file system instance may still have a valid read lease that allows the first file system instance to serve client I/O, directed to the aggregate, using a cache. In order to prevent the first file system instance from serving stale data from the cache before the read lease expires, state machines and a set of control data are used to ensure that the second file system instance attaches to the aggregate only after the read lease has expired.

Abstract: Techniques are provided for remote object store error handling. A storage system may store data within one or more tiers of storage, such as a local storage tier (e.g., solid state storage and disks maintained by the storage system), a remote object store (e.g., storage provided by a third party storage provider), and/or other storage tiers. Because the remote object store may not provide the same data consistency and guarantees that the storage system provides for clients such as through the local storage tier, additional validation is provided by the storage system for the remote object store. For example, when data is put into an object of the remote object store, a verification get operation is performed to read and validate information within a header of the object. Other verifications and checks are performed such as using a locally stored metafile to detect corrupt or lost metadata and/or objects.

Abstract: Methods and systems for co-locating journaling and data storage are provided. Separate journal and volume partitions may be maintained within each logical storage unit (e.g., Logical Unit Number (LUN)) of a distributed storage system. Journaling of metadata associated with write requests received from one or more clients may be distributed by identifying a destination logical storage unit to which data associated with a given write request is to be stored and causing the data and metadata to be persisted to disk by journaling the metadata and the data to respective portions of an active log within the journal partition of the destination logical storage unit. By using the same logical storage unit for both journaling of write requests and writing the data associated with such write requests, the bottleneck due to there being only a single device or storage unit handling all metadata for all write requests can be avoided.

Abstract: Techniques are provided for key-value store and file system integration to optimize key value store operations. A key-value store is integrated within a file system of a node. A log structured merge tree of the key-value store may be populated with a key corresponding to a content hash of a value data item stored separate from the key. A random distribution search may be performed upon a sorted log of the log structured merge tree to identify the key for accessing the value data item. A starting location for the random distribution search is derived from key information, a log size of the sorted log, and/or a keyspace size of a keyspace associated with the key.

Abstract: Techniques are provided for multi-tier write allocation. A storage system may store data within a multi-tier storage environment comprising a first storage tier (e.g., storage devices maintained by the storage system), a second storage tier (e.g., a remote object store provided by a third party storage provider), and/or other storage tiers. A determination is made that data (e.g., data of a write request received by the storage system) is to be stored within the second storage tier. The data is stored into a staging area of the first storage tier. A second storage tier location identifier, for referencing the data according to a format utilized by the second storage tier, is assigned to the data and provided to a file system hosting the data. The data is then destaged from the staging area into the second storage tier, such as within an object stored within the remote object store.

Abstract: Techniques are provided for journal replay optimization. A distributed storage architecture can implement a journal within memory for logging write operations into log records. Latency of executing the write operations is improved because the write operations can be responded back to clients as complete once logged within the journal without having to store the data to higher latency disk storage. If there is a failure, then a replay process is performed to replay the write operations logged within the journal in order to bring a file system up-to-date. The time to complete the replay of the write operations is significantly reduced by caching metadata (e.g., indirect blocks, checksums, buftree identifiers, file block numbers, and consistency point counts) directly into log records. Replay can quickly access this metadata for replaying the write operations because the metadata does not need to be retrieved from the higher latency disk storage into memory.

Abstract: Techniques are provided for storage tier verification checks. A determination is made that a mount operation of an aggregate of a set of volumes stored within a multi-tier storage environment has completed. A first metafile and a second metafile are maintained to track information related to the storage of objects of a volume of the aggregate within a remote object store that is a tier of the multi-tier storage environment. A distributed verification is performed between the first metafile and the second metafile to identify an inconsistency. Accordingly, the first metafile and the second metafile are reconciled to address the inconsistency so that storage information within the first metafile and the second metafile are consistent.

Abstract: A method and system for co-locating journaling and data storage based on write requests. A write request that includes metadata and data is received from a client. A logical storage unit for storing the metadata and the data is identified. The logical storage unit is divided into a journal partition and a volume partition. The journal partition includes a first log and a second log. Which of the first log and the second log is an active log and which of the first log and the second log is an inactive log are identified. The metadata is recorded in a first location in the active log and the data is recorded in a second location in the active log during a single I/O operation. A reply is sent to the client after the metadata and the data are recorded in the journal partition.

Abstract: A method and system for co-locating journaling and data storage based on write requests. A write request that includes metadata and data is received from a client. A logical storage unit for storing the metadata and the data is identified. The logical storage unit is divided into a journal partition and a volume partition. The journal partition includes a first log and a second log. Which of the first log and the second log is an active log and which of the first log and the second log is an inactive log are identified. The metadata is recorded in a first location in the active log and the data is recorded in a second location in the active log during a single I/O operation. A reply is sent to the client after the metadata and the data are recorded in the journal partition.

Abstract: Techniques are provided for journal replay optimization. A distributed storage architecture can implement a journal within memory for logging write operations into log records. Latency of executing the write operations is improved because the write operations can be responded back to clients as complete once logged within the journal without having to store the data to higher latency disk storage. If there is a failure, then a replay process is performed to replay the write operations logged within the journal in order to bring a file system up-to-date. The time to complete the replay of the write operations is significantly reduced by caching metadata (e.g., indirect blocks, checksums, buftree identifiers, file block numbers, and consistency point counts) directly into log records. Replay can quickly access this metadata for replaying the write operations because the metadata does not need to be retrieved from the higher latency disk storage into memory.

Abstract: Techniques are provided for key-value store and file system integration to optimize key value store operations. A key-value store is integrated within a file system of a node. A log structured merge tree of the key-value store may be populated with a key corresponding to a content hash of a value data item stored separate from the key. A random distribution search may be performed upon a sorted log of the log structured merge tree to identify the key for accessing the value data item. A starting location for the random distribution search is derived from key information, a log size of the sorted log, and/or a keyspace size of a keyspace associated with the key.

Abstract: Techniques are provided for multi-tier write allocation. A storage system may store data within a multi-tier storage environment comprising a first storage tier (e.g., storage devices maintained by the storage system), a second storage tier (e.g., a remote object store provided by a third party storage provider), and/or other storage tiers. A determination is made that data (e.g., data of a write request received by the storage system) is to be stored within the second storage tier. The data is stored into a staging area of the first storage tier. A second storage tier location identifier, for referencing the data according to a format utilized by the second storage tier, is assigned to the data and provided to a file system hosting the data. The data is then destaged from the staging area into the second storage tier, such as within an object stored within the remote object store.