Abstract: A storage system writes an object across zones of a set of zones (“zone set”). Each zone of a zone set is contributed from an independently accessible storage medium. To create a zone set, the storage system arbitrarily selects disks to contribute a zone for membership in the zone set. This results in a fairly even distribution of zone sets throughout the storage system, which increases fault tolerance of the storage system. Although disk selection for zone set membership is arbitrary, the arbitrary selection can be from a pool of disks that satisfy one or more criteria (e.g., health or activity based criteria). In addition, weights can be assigned to disks to influence the arbitrary selection. Although manipulating the arbitrary selection with weights or by reducing the pool of disks reduces the arbitrariness, this evenly distributes zone sets while accounting for client demand and/or disk health.

Abstract: Technology is disclosed for deferring storage operations (e.g., writes or reads) during hostile events. When a data storage device experiences a hostile event, e.g., a vibration, shock, etc. contact by a head of the data storage device with a disk surface can cause errors or indeed damage. The technology can cause a data storage device to suspend storage operations until the hostile event is no longer detected.

Abstract: A storage system writes an object across zones of a set of zones (“zone set”). Each zone of a zone set is contributed from an independently accessible storage medium. To create a zone set, the storage system arbitrarily selects disks to contribute a zone for membership in the zone set. This results in a fairly even distribution of zone sets throughout the storage system, which increases fault tolerance of the storage system. Although disk selection for zone set membership is arbitrary, the arbitrary selection can be from a pool of disks that satisfy one or more criteria (e.g., health or activity based criteria). In addition, weights can be assigned to disks to influence the arbitrary selection. Although manipulating the arbitrary selection with weights or by reducing the pool of disks reduces the arbitrariness, this evenly distributes zone sets while accounting for client demand and/or disk health.

Abstract: A durable file system has been designed for storage devices that do not support write in place and/or that are susceptible to errors or failures. The durable file system also facilitates organization and access of large objects (e.g., gigabytes to terabytes in size). Regardless of whether target storage devices are configured with sequential write constraints, the durable file system writes object fragments across a set of sequences or ranges of storage units, such as logical blocks. The durable file system sequentially writes an object fragment into each storage unit sequence along with indexing information for the object fragments. In addition to writing the indexing information for the object fragments into the set of storage unit sequences, the durable file system updates the file system index with the object indexing information.

Abstract: A durable file system has been designed for storage devices that do not support write in place and/or that are susceptible to errors or failures. The durable file system also facilitates organization and access of large objects (e.g., gigabytes to terabytes in size). The durable file system can efficiently reclaim storage space at zone set granularity since each constituent zone can be reclaimed concurrently when the zone set is chosen for space reclamation. Furthermore, space reclamation for the durable file system does not interfere with object availability because the object data is available throughout reclamation. The durable file system copies data of a live object to a different zone set and updates the file system index before reclaiming the target zone set (e.g., before resetting write pointers to the constituent zones).

Abstract: A durable file system has been designed for storage devices that do not support write in place and/or that are susceptible to errors or failures. The durable file system also facilitates organization and access of large objects (e.g., gigabytes to terabytes in size). Since the write of a large object often involves multiple write operations, the writing is also referred to as “ingesting.” When ingesting an object, the durable file system writes the object with indexing information for the object to persistent storage across multiple zones that each map to an independently accessible storage medium (e.g., disks on different spindles). After persisting the indexing information with the object, the durable file system updates a file system index in working memory (e.g., non-volatile system memory) with the indexing information for the object.

Abstract: Technology is disclosed for deferring storage operations (e.g., writes or reads) during hostile events. When a data storage device experiences a hostile event, e.g., a vibration, shock, etc. contact by a head of the data storage device with a disk surface can cause errors or indeed damage. The technology can cause a data storage device to suspend storage operations until the hostile event is no longer detected.

Abstract: Technology is disclosed for deferring storage operations (e.g., writes or reads) during hostile events. When a data storage device experiences a hostile event, e.g., a vibration, shock, etc. contact by a head of the data storage device with a disk surface can cause errors or indeed damage. The technology can cause a data storage device to suspend storage operations until the hostile event is no longer detected.

Abstract: A method of and a system for autonomously identifying which node in a two-node system has failed are described. The system includes two nodes and a fault-tolerant communication fabric. The fabric defines a plurality of communication paths connecting the two nodes, and fault-tolerant loop-back communication in which each node can send a message to itself utilizing at least one switch structure of the fabric. In addition, each of the two nodes includes logic for performing the service; logic for testing the functionality of the respective node; logic for sending test result messages to both nodes; fault-isolation logic for analyzing test result messages from both nodes; and logic for disabling the other node from performing the service only if the fault-isolation logic determines that the respective node is capable of successfully performing the service and also determines that the other node is incapable of successfully performing the service.