Abstract: Techniques are provided for managing snapshot volume trees in a snapshot-enabled data storage system. A snapshot management system is configured to maintain a snapshot volume tree for a storage volume of a storage system, wherein the snapshot volume tree comprises a data structure which comprises a plurality of snapshot volume nodes corresponding to respective ones of (i) a root volume and (ii) multiple snapshots related directly or indirectly to the root volume, wherein the snapshot volume nodes comprise respective generation times which denote times that the respective snapshot volume nodes were created. The generation times are used in conjunction with write times of data items that are written to the snapshot volume nodes to manage snapshot reading and deletion operations.

Abstract: A storage control system receives an I/O request from a client for accessing storage resources that are logically divided into device groups, and determines a resource token request value associated with the I/O request and a target device group to which the I/O request is directed. The storage control system determines a number of allowed resource tokens to allocate to the client as a function of (i) the resource token request value, (ii) a sum total of resource tokens requested by other clients for accessing the target device group, and (iii) a total amount of resource tokens currently allocated to the target device group to which the I/O request is directed. The storage control system sends the determined number of allowed resource tokens to the client to thereby enable the client to limit a number of inflight I/O requests that the client issues to the storage control system.

Abstract: Techniques are provided for managing snapshot volume trees in a snapshot-enabled data storage system. A snapshot management system is configured to maintain a snapshot volume tree for a storage volume of a storage system, wherein the snapshot volume tree comprises a data structure which comprises a plurality of snapshot volume nodes corresponding to respective ones of (i) a root volume and (ii) multiple snapshots related directly or indirectly to the root volume, wherein the snapshot volume nodes comprise respective generation times which denote times that the respective snapshot volume nodes were created. The generation times are used in conjunction with write times of data items that are written to the snapshot volume nodes to manage snapshot reading and deletion operations.

Abstract: A storage control system receives an I/O request from a client for accessing storage resources that are logically divided into device groups, and determines a resource token request value associated with the I/O request and a target device group to which the I/O request is directed. The storage control system determines a number of allowed resource tokens to allocate to the client as a function of (i) the resource token request value, (ii) a sum total of resource tokens requested by other clients for accessing the target device group, and (iii) a total amount of resource tokens currently allocated to the target device group to which the I/O request is directed. The storage control system sends the determined number of allowed resource tokens to the client to thereby enable the client to limit a number of inflight I/O requests that the client issues to the storage control system.

Abstract: A method of managing a distributed storage space. The method comprises mapping a plurality of replica sets to a plurality of storage managing modules installed in a plurality of computing units, each of the plurality of storage managing modules manages access of at least one storage consumer application to replica data of at least one replica of a replica set from the plurality of replica sets, the replica data is stored in at least one drive of a respective the computing unit, allocating at least one time based credit to at least one of each storage managing module and the replica data, iteratively renewing the time based credit as long a failure of at least one of the storage managing module, and the at least one drive and the replica data is not detected plurality of storage managing.

Abstract: A method of managing a distributed storage space. The method comprises mapping a plurality of replica sets to a plurality of storage managing modules installed in a plurality of computing units, each of the plurality of storage managing modules manages access of at least one storage consumer application to replica data of at least one replica of a replica set from the plurality of replica sets, the replica data is stored in at least one drive of a respective the computing unit, allocating at least one time based credit to at least one of each storage managing module and the replica data, iteratively renewing the time based credit as long a failure of at least one of the storage managing module, and the at least one drive and the replica data is not detected plurality of storage managing.

Abstract: A software upgrade tool and procedure provide uninterrupted operation of a replication system during an upgrade of software components of the system. The replication system includes one or more user systems coupled to one or more target storage systems over a communications network, such as a computer network. Illustratively, each user system is embodied as a replication client, while each target storage system is embodied as a replication server. In addition, the replication system includes a management system embodied as a management server that manages configuration of the system, including during upgrade of the software components of the replication system. To that end, the software upgrade tool cooperates with the management server to query the configuration of “old” versions of the software components and to manage upgrades of those components to “new” versions of software.

Abstract: A write ordering style asynchronous replication service utilizes a loosely-accurate global clock in a data backup and recovery storage environment. The storage environment includes a set of source storage systems illustratively embodied as source replication nodes that cooperate to maintain a consistency group that may span multiple geographical sites. The storage environment also includes one or more target storage systems illustratively embodied as target replication nodes configured to service the consistency group. The write ordering style service utilizes the loosely-accurate global clock to provide consistent replication of a storage space of the consistency group.

Abstract: A software upgrade tool and procedure provide uninterrupted operation of a replication system during an upgrade of software components of the system. The replication system includes one or more user systems coupled to one or more target storage systems over a communications network, such as a computer network. Illustratively, each user system is embodied as a replication client, while each target storage system is embodied as a replication server. In addition, the replication system includes a management system embodied as a management server that manages configuration of the system, including during upgrade of the software components of the replication system. To that end, the software upgrade tool cooperates with the management server to query the configuration of “old” versions of the software components and to manage upgrades of those components to “new” versions of software.

Abstract: A write ordering style asynchronous replication service utilizes a loosely-accurate global clock in a data backup and recovery storage environment. The storage environment includes a set of source storage systems illustratively embodied as source replication nodes that cooperate to maintain a consistency group that may span multiple geographical sites. The storage environment also includes one or more target storage systems illustratively embodied as target replication nodes configured to service the consistency group. The write ordering style service utilizes the loosely-accurate global clock to provide consistent replication of a storage space of the consistency group.