Abstract: A method is used in managing storage space in storage systems. Storage space reserved by a storage object from a set of storage tiers is evaluated. A data storage system includes the first and second storage tiers configured such that performance characteristics associated with the first storage tier is different from the second storage tier. Based on the evaluation, storage space available and consumed in each storage tier of the set of storage tiers is determined.

Abstract: Techniques for creating and using snapshots may include: receiving a request to create a new snapshot of a source object; determining whether a first generation identifier associated with the source object matches a second generation identifier associated with a base snapshot of the source object; determining whether the source object has been modified since the base snapshot was created; and responsive to determining the first generation identifier matches the second generation identifier and also determining that the source object has not been modified since the base snapshot was created, associating the new snapshot with the base snapshot thereby indicating that the new snapshot and the base snapshot have matching content and denote a same point in time copy of the source object.

Abstract: A method performed by a data storage apparatus of maintaining filesystem object attributes in connection with a plurality of drivers is provided. Each driver of the plurality is configured to operate on a respective set of filesystem objects. The method includes (a) for each driver of the plurality, creating a respective driver-specific storage volume; (b) storing, within each driver-specific storage volume, attributes specific to respective filesystem objects operated on by the driver of that driver-specific storage volume; and (c) while operating a particular driver of the plurality on a particular filesystem object, using values of the stored attributes specific to that particular filesystem object operated on by that particular driver. An apparatus, system, and computer program product for performing a similar method are also provided.

Abstract: Techniques for creating and using snapshots may include: receiving a request to create a new snapshot of a source object; determining whether a first generation identifier associated with the source object matches a second generation identifier associated with a base snapshot of the source object; determining whether the source object has been modified since the base snapshot was created; and responsive to determining the first generation identifier matches the second generation identifier and also determining that the source object has not been modified since the base snapshot was created, associating the new snapshot with the base snapshot thereby indicating that the new snapshot and the base snapshot have matching content and denote a same point in time copy of the source object.

Abstract: A method, computer program product, and computer system for receiving, at a computing device, a write request from a host, wherein a first portion of a process may receive the write request. A callback and context may be set in the write request by the first portion of the process. The write request may be passed to a second portion of the process. The first process may be provided with the context. The first process may use the context to replicate the write request data to a destination.

Abstract: A method, computer program product, and computer system for receiving, at a computing device, a write request from a host, wherein a first portion of a process may receive the write request. A callback and context may be set in the write request by the first portion of the process. The write request may be passed to a second portion of the process. The first process may be provided with the context. The first process may use the context to replicate the write request data to a destination.

Abstract: Techniques are presented for implementing a scalable approach to keeping track of the metadata validity of persistently-stored metadata for storage objects. In contrast with prior approaches, improved techniques only store a list of the invalid (or quarantined) objects rather than all objects regardless of validity of their metadata. Under normal circumstances, only a small number of storage objects are invalid at any given time, as the system generally takes steps to repair the invalid objects in the normal course of operation. Thus, the number of invalid objects tends to be small, barring some catastrophic system failure. Only a small amount of expensive privileged persistent storage is therefore needed. A health level may also be used to indicate many failures, indicative of catastrophic system failure.

Abstract: Techniques are presented for implementing a scalable approach to keeping track of the metadata validity of persistently-stored metadata for storage objects. In contrast with prior approaches, improved techniques only store a list of the invalid (or quarantined) objects rather than all objects regardless of validity of their metadata. Under normal circumstances, only a small number of storage objects are invalid at any given time, as the system generally takes steps to repair the invalid objects in the normal course of operation. Thus, the number of invalid objects tends to be small, barring some catastrophic system failure. Only a small amount of expensive privileged persistent storage is therefore needed. A health level may also be used to indicate many failures, indicative of catastrophic system failure.

Abstract: A technique for copying a source data object within a data storage system to a destination includes ingesting data portions of the source object into respective pages of a cache. The cache associates the pages with respective descriptors and writes into the descriptors locations of storage elements that have been provided for storing the respective data portions at the destination. When later flushing these cache pages, each page is flushed to the location at the destination that is provided in the respective descriptor.

Abstract: A technique for managing file system expansions includes receiving a request to perform a file system expansion, the request specifying or implying an increase in size of a file system to a new target size. The request is received while a previous file system expansion is already in progress. The technique includes merging the previous file system expansion into the file system expansion specified by the request, to increase the size of the file system to the new target size.

Abstract: There are disclosed techniques for use in managing data copying. In one embodiment, there is disclosed a method including a number of steps. The method comprises performing a first operation to copy data from a first region of a source area. The method also comprises determining a count relating to pending I/O requests in connection with a second region of the source area upon completion of the first operation. And, in response to determining that the count relating to pending I/O requests in connection with the second region of the source area equals zero, the method further comprises performing a second operation to copy data from the second region of the source area and configuring a new region in the source area to record a count relating to pending I/O requests in connection with the source area.

Abstract: A technique for providing access to a data object serving as a target of snapshot-shipping replication includes taking a system snap of the data object after completion of each of multiple snapshot-shipping updates. In response to receiving a request to take a user snap of the data object, a data storage system redirects the request to a previously generated system snap, so that the data storage system takes the user snap of the system snap rather than taking the user snap of the data object itself.

Abstract: A technique for managing copy sessions in a data storage system supports active and inactive copy-session states and reclaims memory for inactive copy sessions to reduce their memory footprints. When a copy session transitions from the active state to the inactive state, the copy session persists certain copy-progress data in non-volatile storage and frees structures in memory previously storing that copy-progress data. The inactive copy session continues to run but performs no copying and consumes less memory. When the copy session later transitions back to the active state, the copy session reads the copy-progress data back into memory and resumes copying.

Abstract: A method includes (a) receiving a command to create an upper-deck filesystem of a specified size, the upper-deck filesystem residing within a logical volume expressed from a container file of a lower-deck filesystem, (b) provisioning a plurality of storage provisioning units (SPUs) from a storage pool of the data storage system to the container file in an order reflecting proximity of the SPUs within storage devices of the data storage system, the plurality of SPUs providing storage for the entire container file, and (c) subsequent to provisioning the plurality of SPUs to the container file, executing a plurality of threads in parallel to write metadata of the upper-deck filesystem to the plurality of SPUs, representing the upper-deck filesystem. Other embodiments are directed to a system, a computerized apparatus, and a computer program product for performing methods similar to that described above.

Abstract: A technique for providing access to a data object serving as a target of snapshot-shipping replication includes taking a system snap of the data object after completion of each of multiple snapshot-shipping updates. In response to a data storage system receiving an IO (input/output) request to read and/or write to the data object, a data storage system redirects the IO request to a previously generated system snap, so that the data storage system performs the operation specified in the IO request on the system snap rather than of the data object itself.

Abstract: Techniques for processing requests are described. A first thread is selected for execution. Only a single thread is allowed to execute at a time. Each thread is associated with a queue of requests to be processed by the thread. A first request is selected from the queue of first thread that performs first processing to service the first request. A service time classification for the first request is determined in accordance with criteria that includes a runtime determination of what resource(s) are used in servicing the first request. It is determined, in accordance with the service time classification, whether to allow the first thread to continue execution and process a second request from the queue of the first thread. If the first thread is allowed to continue execution, second processing is performed by the first thread to service the second request. Otherwise, a second thread is selected for execution.

Abstract: A method is used in managing provisioning of storage in storage systems. Whether a logical object requires a slice for recovering the logical object is determined. Based on the determination, storage for the slice is provisioned. The slice is provided to the logical object.

Abstract: A method is used in managing properties collection. Storage objects for which properties information is to be refreshed are determined. A bulk request for properties information from file systems corresponding to the storage objects is generated and is issued to the file systems. Based on a response to the bulk request, a blocking transaction is used to update a model of the storage objects that is made available to management software.