Abstract: Implementations for dropped write detection and correction are described. An example method includes receiving a write command comprising data and associated metadata; increasing a value of a monotonic counter; generating updated metadata by adding the counter value to the metadata; atomically writing (a) the data and a first instance of the updated metadata to a first storage device, and (b) a second instance of the updated metadata to a second storage device; receiving a read request for the data; reading the first instance of the updated metadata from the first storage device; reading the second instance of the updated metadata from a second storage device; comparing the instances of metadata and the counter values within each instance of metadata; determining whether the first counter value matches the second counter value; and determining whether a dropped write has occurred based on whether the first counter values matches the second counter value.

Abstract: Techniques for providing high-performance buffer caches for transactional input/output (I/O) systems are disclosed. The techniques include obtaining a first logical creation time of a resource to be acquired by the first transaction during a pre-commit phase of a first transaction with an I/O system. When the first logical creation time exceeds a latest logical creation time from a set of resources previously acquired by the first transaction, the first logical creation time of the resource is compared with an earliest logical termination time from the set of resources. When the first logical creation time of the resource exceeds the earliest logical termination time from the set of resources, a conflict between the resource and the set of resources is detected, and a restart of the first transaction is triggered.

Abstract: Techniques for providing high-performance writable snapshots in data storage systems are disclosed. The techniques include storing a set of snapshots containing changes to a data set over time in a set of allocation units containing a series of contiguous blocks. A set of metadata blocks in the allocation units is used to track a state of data stored in the series of contiguous blocks. Ownership of the allocation units by the snapshots is also tracked in a set of allocation unit mappings between the allocation units and a set of snapshot identifiers representing the snapshots. The allocation unit mappings and metadata blocks are then used to execute writes to the data set and free blocks in the snapshots.

Abstract: Techniques for providing high-performance buffer caches for transactional input/output (I/O) systems are disclosed. The techniques include obtaining a first logical creation time of a resource to be acquired by the first transaction during a pre-commit phase of a first transaction with an I/O system. When the first logical creation time exceeds a latest logical creation time from a set of resources previously acquired by the first transaction, the first logical creation time of the resource is compared with an earliest logical termination time from the set of resources. When the first logical creation time of the resource exceeds the earliest logical termination time from the set of resources, a conflict between the resource and the set of resources is detected, and a restart of the first transaction is triggered.

Abstract: Techniques for providing high-performance buffer caches for transactional input/output (I/O) systems are disclosed. The techniques include obtaining a first logical creation time of a resource to be acquired by the first transaction during a pre-commit phase of a first transaction with an I/O system. When the first logical creation time exceeds a latest logical creation time from a set of resources previously acquired by the first transaction, the first logical creation time of the resource is compared with an earliest logical termination time from the set of resources. When the first logical creation time of the resource exceeds the earliest logical termination time from the set of resources, a conflict between the resource and the set of resources is detected, and a restart of the first transaction is triggered.

Abstract: Techniques for providing high-performance buffer caches for transactional input/output (I/O) systems are disclosed. The techniques include obtaining a first logical creation time of a resource to be acquired by the first transaction during a pre-commit phase of a first transaction with an I/O system. When the first logical creation time exceeds a latest logical creation time from a set of resources previously acquired by the first transaction, the first logical creation time of the resource is compared with an earliest logical termination time from the set of resources. When the first logical creation time of the resource exceeds the earliest logical termination time from the set of resources, a conflict between the resource and the set of resources is detected, and a restart of the first transaction is triggered.

Abstract: Techniques for providing high-performance writable snapshots in data storage systems are disclosed. The techniques include storing a set of snapshots containing changes to a data set over time in a set of allocation units containing a series of contiguous blocks. A set of metadata blocks in the allocation units is used to track a state of data stored in the series of contiguous blocks. Ownership of the allocation units by the snapshots is also tracked in a set of allocation unit mappings between the allocation units and a set of snapshot identifiers representing the snapshots. The allocation unit mappings and metadata blocks are then used to execute writes to the data set and free blocks in the snapshots.

Abstract: Techniques for providing high-performance writable snapshots in data storage systems are disclosed. The techniques include storing a set of snapshots containing changes to a data set over time in a set of allocation units containing a series of contiguous blocks. A set of metadata blocks in the allocation units is used to track a state of data stored in the series of contiguous blocks. Ownership of the allocation units by the snapshots is also tracked in a set of allocation unit mappings between the allocation units and a set of snapshot identifiers representing the snapshots. The allocation unit mappings and metadata blocks are then used to execute writes to the data set and free blocks in the snapshots.

Abstract: Techniques for providing high-performance buffer caches for transactional input/output (I/O) systems are disclosed. The techniques include obtaining a first logical creation time of a resource to be acquired by the first transaction during a pre-commit phase of a first transaction with an I/O system. When the first logical creation time exceeds a latest logical creation time from a set of resources previously acquired by the first transaction, the first logical creation time of the resource is compared with an earliest logical termination time from the set of resources. When the first logical creation time of the resource exceeds the earliest logical termination time from the set of resources, a conflict between the resource and the set of resources is detected, and a restart of the first transaction is triggered.

Abstract: Techniques for providing high-performance writable snapshots in data storage systems are disclosed. The techniques include storing a set of snapshots containing changes to a data set over time in a set of allocation units containing a series of contiguous blocks. A set of metadata blocks in the allocation units is used to track a state of data stored in the series of contiguous blocks. Ownership of the allocation units by the snapshots is also tracked in a set of allocation unit mappings between the allocation units and a set of snapshot identifiers representing the snapshots. The allocation unit mappings and metadata blocks are then used to execute writes to the data set and free blocks in the snapshots.

Abstract: The invention relates to a multiple QoS file system and methods of processing files at different QoS according to rules. The invention allocates multiple VLUNs at different qualities of service to the multiQoS file system. Using the rules, the file system chooses an initial QoS for a file when created. Thereafter, the file system moves files to different QoS using rules. Users of the file system see a single unified space of files, while administrators place files on storage with the new cost and performance according to attributes of the files. A multiQoS file system enhances the descriptive information for each file to contain the chosen QoS for the file.

Abstract: The invention relates to a multiple QoS file system and methods of processing files at different QoS. The file system allocates VLUNs and using rules chooses an initial QoS for a file when created and moves files to different QoS using rules. Users see a single unified space of files, while administrators place files on storage according to file attributes. A file system enhances the descriptive information for each file to contain the chosen QoS for the file. The invention classifies volumes (e.g., file systems or LUNs) according to application requirements and allocates space for volumes. An IT administrator configures volumes specifying size, type and priority. The host schedules I/O requests in priority queues using the volume definition to match applications and reduce seek time between volumes of different priorities. The data storage system therefore places data on the performance band of a storage device that best supports needs.

Abstract: The invention relates to a multiple QoS file system and methods of processing files at different QoS. The file system allocates VLUNs and using rules chooses an initial QoS for a file when created and moves files to different QoS using rules. Users see a single unified space of files, while administrators place files on storage according to file attributes. A file system enhances the descriptive information for each file to contain the chosen QoS for the file. The invention classifies volumes (e.g., file systems or LUNs) according to application requirements and allocates space for volumes. An IT administrator configures volumes specifying size, type and priority. The host schedules I/O requests in priority queues using the volume definition to match applications and reduce seek time between volumes of different priorities. The data storage system therefore places data on the performance band of a storage device that best supports needs.

Abstract: The invention relates to a multiple QoS file system and methods of processing files at different QoS according to rules. The invention allocates multiple VLUNs at different qualities of service to the multiQoS file system. Using the rules, the file system chooses an initial QoS for a file when created. Thereafter, the file system moves files to different QoS using rules. Users of the file system see a single unified space of files, while administrators place files on storage with the new cost and performance according to attributes of the files. A multiQoS file system enhances the descriptive information for each file to contain the chosen QoS for the file.

Abstract: The invention relates to a multiple QoS file system and methods of processing files at different QoS according to rules. The invention allocates multiple VLUNs at different qualities of service to the multiQoS file system. Using the rules, the file system chooses an initial QoS for a file when created. Thereafter, the file system moves files to different QoS using rules. Users of the file system see a single unified space of files, while administration place files on storage with the new cost and performance according to attributes of the files. A multiQoS file system enhances the descriptive information for each file to contain the chosen QoS for the file.

Abstract: The invention relates to a multiple QoS file system and methods of processing files at different QoS according to rules. The invention allocates multiple VLUNs at different qualities of service to the multiQoS file system. Using the rules, the file system chooses an initial QoS for a file when created. Thereafter, the file system moves files to different QoS using rules. Users of the file system see a single unified space of files, while administrators place files on storage with the new cost and performance according to attributes of the files. A multiQoS file system enhances the descriptive information for each file to contain the chosen QoS for the file.