Abstract: A method for managing lost content change requests (CCRs), the method includes (i) maintaining, by compute entities of a second storage system (SSS), states of executions of multiple CCRs of multiple categories and of multiple SSS reception times; (ii) receiving, from a first storage system (FSS), at a failure indication reception time (FIRT), a failure indication that is indicative of a certain category of the multiple categories. The certain category is associated with a failure of the FSS to receive a response, from the SSS, to a certain CCR of the certain category, that was presumably sent from the FSS to the SSS; (iii) determining, based on states of executions that are related at least to the certain category, when the SSS has completed to execute all CCRs of at least the certain category that were received by the SSS up to the FIRT; and (iv) transmitting, by the SSS, a SSS completion indication that indicates that the SSS has completed to execute all tasks that were received by the SSS up to the FIRT.

Abstract: A method for writing data to a shared write buffer, the method includes (i) receiving, by a processing circuit of a compute node of a storage system, a write request for writing to the shared write buffer an information unit associated with an accessing entity located outside the storage system; wherein the shared write buffer is stored in a non-volatile memory of a storage node of the storage system; the storage node is in communication with the compute node; (ii) determining, by the processing circuit whether to (a) store the information unit in a non-shared segment of the shared write buffer, or (b) store the information unit in a shared segment of the shared write buffer while applying a locking mechanism; wherein the determining is based on parameters, the parameters include a writing parameter of the accessing entity, a writing latency parameter associated with the accessing entity, and a locking timing parameter; and (iii) storing the information unit according to the determination.

Abstract: A method for responding to a query, the method may include (a) receiving, by a storage system compute element, a query that comprises one or more conditions related to a content of at least one data unit (DU); (b) searching, based on the one or more conditions and on a condition fulfillment information (CFI), for one or more irrelevant groups of DUs to be skipped during the responding to the query; wherein the one or more irrelevant groups of DUs belong to multiple stored groups of DUs that are stored in the storage system; wherein an irrelevant group of DU does not comprise, according to the CFI, any DU that fulfills the one or more conditions; and (c) generating a response to the query based on an outcome of the searching.

Abstract: A method for compression of cells of a tabular database (TD), the method may include (i) receiving data elements, by a storage system; (ii) calculating a compressed representation (CR) of the data elements by applying a compression process that includes (ii.a) defining sets based on data element values, (ii.b) associating a set value per set; and (ii.c) generating the CR of the data elements based on differences between the data elements and corresponding set values; (iii) generating compression metadata related to the CR of the data elements, wherein the compression metadata comprises the set values and a mapping between the CR of the data elements and the set values; and (iv) storing, in the TD, the CR of the data elements.

Abstract: A method for managing tasks in a storage system, the method may include: (a) obtaining, by a scheduler, a shared budget for background storage tasks and foreground storage tasks; (b) obtaining, by the scheduler, a background budget for background storage tasks; wherein the background budget is a fraction of the shared budget; (c) allocating, by the scheduler, resources to pending storage tasks according to the shared budget and the background budget; wherein the allocating comprises (i) allocating the shared budget while prioritizing foreground storage tasks over background storage tasks; and (ii) allocating the background budget to background storage tasks; and (d) participating, by the scheduler, in executing of storage tasks according to the allocation.

Abstract: A method for transitioning from asynchronous replication to a synchronous replication, the method includes (i) receiving, by a DSS and following the start of the transitioning, a synchronous update related to a first FSE part; (ii) implementing the synchronous update of the first FSE part; (iii) receiving, by the DSS and following the start of the transitioning, an asynchronous update related to a last version of a second FSE part before the start of the transitioning; (iv) ignoring the asynchronous update when the DSS currently stores a version of the second FSE part that is associated with a timestamp that is indicative of a point in time that exceeds the start of the transitioning; and (v) else—implementing the asynchronous update.

Abstract: A method for updating file system entity (FSE) metadata. The method may include receiving, by a first computing entity, a request to perform a case-sensitive FSE operation that comprises one of (a) adding a case-sensitive version of a name of a FSE to a data structure, or (b) deleting the case-sensitive version of the name of the FSE from the data structure, the data structure comprises multiple name blocks; finding, by the first computing entity, a certain name block of the multiple name blocks that is associated with the case-sensitive version of the name of the FSE.

Abstract: A method for accessing a database that is stored in a storage system, the method includes: (a) receiving a request to obtain a database entity (DE) of a requested version line out of multiple version lines that differ from each other by one or more transactions; (b) obtaining, for each DE portion out of multiple DE portions of the DE, content of the DE portion as written during a transaction of the requested version line that was a last transaction of the requested version line that wrote the DE portion to the database; wherein the obtaining includes (i) using first metadata that is indicative of transactions of the requested version line, and (ii) using second metadata that is indicative of which transactions were involved in writing to a logical address range that is associated with the DE portion; and (d) sending a response to the request, wherein the response comprises, for each DE portion of the DE portions, the obtained content.

Abstract: A method for responding to access requests, the method may include (a) detecting, by a controller of a local storage system (LSS), a read pattern that (i) is associated with a requestor that is in communication with the LSS, and (ii) is estimated to comprise future read requests that are aimed to a remote part of a file system entity (FSE) that is stored at a remote storage system (RSS); wherein there is a latency difference between a remote latency associated with the remote part of the FSE and a LSS latency that is associated with the requestor; and (b) performing a prefetch process of remote sub-parts of the remote part of the FSE in order to support the read pattern while maintaining a desired latency.

Abstract: A method for network group based access control, the method may include (i) receiving a request to access content stored in a storage system, the request is associated with a user and a network group that is suggested to include the user; (ii) generating a user key based on an identifier of the user and the network group; (iii) determining, based in part on the user key, whether the user is a current user of the network group, and (iv) declining the request when the user is not the current user of the network group. The determining may include determining that the user is not a current user of the network group when a user finding timestamp of the user precedes a network group finding timestamp of the network group.

Abstract: A method for obtaining information related to a filesystem path in a file system that is stored in a storage system, the method may include (i) receiving a request to obtain hierarchy information related to file system entities stored under the filesystem path; and (ii) retrieving the hierarchy information; wherein the retrieving comprises accessing a filesystem hierarchy table that stores information regarding pathnames of file system entities of the file system; wherein the retrieving includes searching for path components of the filesystem path in subsets of cells of the filesystem hierarchy table, wherein each subset of cells is part of a set of cells that include path components of a certain pathname of a filesystem entity that belong to the file system.

Abstract: A method for protecting a lock data structure, the method includes obtaining, by a compute entity of a storage system, a lock recovery indication and a cycle counter; executing, by the compute entity, at least a part of the current lock recovery process, wherein the executing of the at least part of the current lock recovery process includes (i) determining, by the compute entity, using a compute entity data structure that is indicative of lock fields that represent locks acquired by the compute entity, whether the segment comprised a compute-entity-relevant lock field, wherein the compute-entity-relevant lock field (a) belonged to the segment upon the occurrence of the failure and (b) represents a lock was acquired by the compute entity; and (ii) re-acquiring, by the compute entity, a re-acquired lock that corresponds to the compute-entity-relevant lock field, when it is determined that the segment comprised the compute-entity-relevant lock field.

Abstract: A method for protecting a disaster recovery site, the method may include receiving by source compute nodes of a storage system, during source storage periods, write requests for storing content in the storage system; writing by source compute nodes, during the source storage periods, the content into the storage nodes of the storage system; maintaining replication compute nodes of the storage system deactivated during the source storage periods; reading the content by the replication compute nodes from the storage nodes during replication periods; participating, by the replication compute nodes, in outputting the content to one or more data recovery sites during the replication periods; and maintaining the source compute nodes deactivated during the source storage periods.

Abstract: A method for determining size information related one or more file systems stored in a storage system, the method may include (i) sampling one or more logical spaces that are associated with the one or more file systems to provide sampled file system entities (FSEs); wherein a number of samples per sampled FSE is indicative of a size of the sampled FSEs; and (ii) determining logical sizes and physical sizes of different levels of the one or more file systems based on the sampled file system entities.

Abstract: A method for managing a transaction data structure, the method may include (a) receiving, at a first point in time that corresponds to a first value of a clock signal, a request to commit a transaction, and updating a status of the transaction, within the transaction data structure, as being a commit in progress; (b) updating the status of the transaction within the transaction data structure as being committed following (i) a completion of the committing, and (ii) a change of a value of the clock signal from the first value to a second value that differs from the first value; and (c) updating, using a background process, a database segment (DS) version metadata associated with the transaction regarding the completion of the committing. The DS version metadata belongs to a DS version metadata data structure. The DS version metadata data structure and the transaction data structure are selectively accessed during transactions.

Abstract: A method for storing a received data chunk (DC) in a storage system, the method includes (a) obtaining a received fingerprint of the received DC, the received fingerprint may include received fingerprint elements that are indicative of occurrences, within the received DC, of content elements, the received fingerprint elements are ordered according to a given order; (b) searching, within a tree, for a similar stored fingerprint; the tree may include tree nodes that represent multiple stored fingerprints of stored data chunks that are stored in the storage system; different levels of the tree are allocated to different content elements; (c) compressing, when finding the similar stored fingerprint, the received DC based on a similar DC associated with the similar stored fingerprint, and updating storage system metadata to indicate that the received DC is stored in the storage system in a compressed form, and based on the similar stored DC.

Abstract: A method for securing a storage system, the method may include detecting, by cybersecurity engine, a suspected file that is stored in the storage system; autonomously searching for one of more files that fulfill one or more similarity criteria in relation to the suspected file; wherein the one or more similar files are stored in a storage system; finding, by the similarity engine, the one or more similar files using a similarity data structure that associates a group of files stored in the storage system with (a) inter-file similarity scores and (b) block hash values shared between files; and responding to the finding, wherein the responding comprises sending the one of more similar files to the cybersecurity engine.

Abstract: A method for reading a shared clock that is stored in a shared storage space of a storage system, the method may include (a) reading by a compute node a cached value of the shared clock when a time gap before a next update of the shared clock exceeds a time threshold, wherein the cached value is cached in the compute node and is valid during an allowable caching period, wherein the shared clock is shared by a group of compute nodes, wherein a default update of the shared clock has a cycle that exceeds the time threshold; and (b) reading by the compute node a read value of the shared clock when the time gap before the next update of the shared clock does not exceed the time threshold, wherein the read value of the shared clock is stored in the shared storage space.

Abstract: A method for managing access to a shared file system entity (FSE), the method includes (i) managing access requests for reading and writing accessed parts of the FSE, by a current point of access storage system (POASS), the current POASS currently acts as a point of access (POA) for the access requests; wherein stored parts of the FSE are stored at multiple POASSs, the multiple POASSs comprise the current POASS and former POASSs; (ii) determining, by the current POASS and while managing the access requests, to store the stored parts of the FSE at a fewer number of the former POASSs; and (iii) reducing, by two or more of the former POASSs, the number of former POASSs that store the stored parts of the FSE.

Abstract: A method for determining a progress of an execution of a task, the method may include accessing only a portion of a shared task status data structure that (a) is associated with the task, wherein the task is executed by a first plurality of compute elements, and (b) comprises multiple hierarchical levels; wherein an entry of a certain hierarchical level represents an aggregate progress associated with multiple entries of the another hierarchical level; the certain hierarchical level is higher than the other hierarchical level; and determining the progress of the execution of the task based on a content of the portion.