Abstract: Intelligent, transaction-aware table placement minimizes cross-host transactions while supporting full transactional semantics and delivering high throughput at low resource utilization. This placement reducing delays caused by cross-host transaction coordination. Examples determine a count of historical interactions between tables, based on at least a transaction history for a plurality of cross-table transactions. Each table provides an abstraction for data, such as by identifying data objects stored in a data lake. For tables on different hosts, having high count of historical interactions, potential cost savings achievable by moving operational control of a first table to the same host as the second table is compared with the potential cost savings achievable by moving operational control of the second table to the same host as the first table. Based on comparing the relative cost savings, one of the tables may be selected.

Abstract: A version control interface for data provides a layer of abstraction that permits multiple readers and writers to access data lakes concurrently. An overlay file system, based on a data structure such as a tree, is used on top of one or more underlying storage instances to implement the interface. Each tree node tree is identified and accessed by means of any universally unique identifiers. Copy-on-write with the tree data structure implements snapshots of the overlay file system. The snapshots support a long-lived master branch, with point-in-time snapshots of its history, and one or more short-lived private branches. As data objects are written to the data lake, the private branch corresponding to a writer is updated. The private branches are merged back into the master branch using any merging logic, and conflict resolution policies are implemented. Readers read from the updated master branch or from any of the private branches.

Abstract: A version control interface provides for time travel with metadata management under a common transaction domain as the data. Examples generate a time-series of master branch snapshots for data objects stored in a data lake, with the snapshot comprising a tree data structure such as a hash tree and associated with a time indication. Readers select a master branch snapshot from the time-series, based on selection criteria (e.g., time) and use references in the selected master branch snapshot to read data objects from the data lake. This provides readers with a view of the data as of a specified time.

Abstract: Techniques for efficiently managing a file clone from a filesystem which supports efficient volume snapshots are provided. In some embodiments, a system may receive an instruction to remove the file clone from the filesystem. The file clone may be a point-in-time copy of metadata of an original file. The system may further—for a file map entry in a filesystem tree associated with the file clone, the file map entry indicating a data block—decrement a reference count in a reference count entry associated with the file map entry. The reference count entry may be stored in the filesystem tree according to a key and the key may comprise an identification of the original file. The system may further reclaim the data block in a storage system when the reference count is zero.

Abstract: Exemplary methods, apparatuses, and systems include a file system process obtaining locks on a first node and a second node in a tree structure, with the second node being a child node of the first node. The file system process determines a quantity of child nodes of the second. While holding the locks on the first and second nodes, the file system determines whether to proactively split or merge the second node. In response to determining that the quantity of child nodes is within a first range, the file system process splits the second node. If the file system process determines that the quantity of child nodes is within a second range, the file system process merges the second node.

Abstract: A version control interface provides for accessing a data lake with transactional semantics. Examples generate a plurality of tables for data objects stored in the data lake. The tables each comprise a set of name fields and map a space of columns or rows to a set of the data objects. Transactions read and write data objects and may span a plurality of tables with properties of atomicity, consistency, isolation, durability (ACID). Performing the transaction comprises: accumulating transaction-incomplete messages, indicating that the transaction is incomplete, until a transaction-complete message is received, indicating that the transaction is complete. Upon this occurring, a master branch is updated to reference the data objects according to the transaction-incomplete messages and the transaction-complete message. Tables may be grouped into data groups that provide atomicity boundaries so that different groups may be served by different master branches, thereby improving the speed of master branch updates.

Abstract: The disclosure provides techniques for deduplicating files. The techniques include, upon creating or modifying a file, placing a logical timestamp of the current logical time, within a queue associated with the directory of the file. The techniques further include placing the logical timestamp within a queue of each parent directory of the directory of the file. To determine a set of files for deduplication, the techniques disclosed herein identify files that have been modified within a logical time range. The set of files modified within a logical time is identified by traversing directories of a storage system, the directories being organized within a tree structure. If a directory's queue does not contain a timestamp that is within the logical time range, then all child directories can be skipped over for further processing, such that no files within the child directories end up being within the set of files for deduplication.

Abstract: Optimizing file access includes a process for identifying a file access event for a first accessed file, and incrementing a first access counter in an access list in a memory, which also includes access counters for other accessed files. The process further includes exporting the first access counter to a performance monitoring dashboard, or exporting to a storage allocator and, based on the value, moving the first accessed file between a first storage and a second storage. The process also includes determining whether the value of the first access counter meets a first threshold, or a sum of values of the access counters for the other accessed files meets a second threshold. Based on meeting the first threshold or meeting the second threshold, the process includes persisting the access counters on a storage media. The access counters also provide security monitoring (e.g., identifying excessive file access).

Abstract: Exemplary methods, apparatuses, and systems include a file system process reading a first node in a tree data structure from a first memory. The first node includes a first approximate membership query data structure (“AMQ”), a first plurality of child pointers, a first plurality of pivot values, and a first buffer. The file system process determines that the first plurality of child pointers exceeds a maximum size. Using a pivot value in the first plurality of pivot values, the file system process splits the first node into a second node and a third node. The file system process uses the pivot value to split the first buffer into a second buffer and a third buffer. Using the pivot value and the first AMQ, the file system process generates a second AMQ and a third AMQ.

Abstract: A version control interface for data provides a layer of abstraction that permits multiple readers and writers to access data lakes concurrently. An overlay file system, based on a data structure such as a tree, is used on top of one or more underlying storage instances to implement the interface. Each tree node tree is identified and accessed by means of any universally unique identifiers. Copy-on-write with the tree data structure implements snapshots of the overlay file system. The snapshots support a long-lived master branch, with point-in-time snapshots of its history, and one or more short-lived private branches. As data objects are written to the data lake, the private branch corresponding to a writer is updated. The private branches are merged back into the master branch using any merging logic, and conflict resolution policies are implemented. Readers read from the updated master branch or from any of the private branches.

Abstract: Disclosed techniques include deduplication. Techniques include determining whether a file is unique, and depending on whether the file is unique, deduplicating only part of the file or the entire file. The techniques include processing the first chunk of a file to determine whether the hash of the chunk hash is already within a chunk hash table, and if not, then a percentage of chunks of the file is similarly processed. If any of the hashes of chunks are already in the chunk hash table, then at least some of file has been previously deduplicated, and file is not unique the storage system. If none of the processed chunks have a hash that is already in the chunk hash table, then the file is considered to be unique within chunk store and only a partial percentage of the file's chunks are deduplicated. Not all of a unique file's chunks are deduplicated.

Abstract: The disclosure herein describes writing data to a log-structured merge (LSM) tree file system on an object storage platform. Write data instructions indicating data for writing to the LSM tree file system are received. Based on the received instructions, the data is written to the first data cache. Based on an instruction to transfer data in the live data cache to the LSM tree file system, the first data cache is converted to a stable cache. A second data cache configured as a live data cache is then generated based on cloning the first data cache. The data in the first data cache is then written to the LSM tree file system. Use of a stable cache and a cloned live data cache enables parallel writing data to the file system by the stable cache and handling write data instructions by the live data cache.

Abstract: Techniques for efficiently managing a file clone from a filesystem which supports efficient volume snapshots are provided. In some embodiments, a system may receive an instruction to remove the file clone from the filesystem. The file clone may be a point-in-time copy of metadata of an original file. The system may further—for a file map entry in a filesystem tree associated with the file clone, the file map entry indicating a data block—decrement a reference count in a reference count entry associated with the file map entry. The reference count entry may be stored in the filesystem tree according to a key and the key may comprise an identification of the original file. The system may further reclaim the data block in a storage system when the reference count is zero.

Abstract: The disclosure herein describes management of distribution of resources between a global pool and an associated plurality of local pools using a flush threshold. A request for resources is received at the global pool from a local pool, the request indicating a requested quantity of resources. Based on the received request, it is determined that available resources in the global pool are below a flush threshold of the global pool. Based on this determination, flush instructions are sent to the local pools, wherein the flush instructions instruct each local pool to release unused resources (e.g., available to be released) to the global pool. Based on the available resources of the global pool then exceeding the requested quantity of resources and/or the flush threshold, resources of the global pool are allocated to the requesting local pool, whereby the local pool is enabled to use the allocated resources.

Abstract: Exemplary methods, apparatuses, and systems include a file system process inserting a first key/value pair and a second key/value pair into a first tree. The second key is a duplicate of the first key and the value of the second key/value pair is an operation changing the value. In response to a request for a range of key/value pairs, the process reads the second key/value pair and inserts it in a second tree. The process reads the first pair and determines, while inserting the first pair in the second tree, that the second key is a duplicate of the first key. The file system process determines an updated value of the first value by applying the operation in the second value to first value. The file system operation updates the second key/value pair in the second tree with the updated value and returns the requested range of key/value pairs.

Abstract: An example method of memory management in a computing system having a plurality of processors includes: receiving a first memory allocation request at a memory manager from a process executing on a processor of the plurality of processors in the computing system; allocating a local memory pool for the processor from a global memory pool for the plurality of processors in response to the first memory allocation request; and allocating memory from the local memory pool for the processor in response to the first memory allocation request without locking the local memory pool.

Abstract: Techniques for efficiently managing a file clone from a filesystem which supports efficient volume snapshots are provided. In some embodiments, a system may receive an instruction to remove the file clone from the filesystem. The file clone may be a point-in-time copy of metadata of an original file. The system may further—for a file map entry in a filesystem tree associated with the file clone, the file map entry indicating a data block—decrement a reference count in a reference count entry associated with the file map entry. The reference count entry may be stored in the filesystem tree according to a key and the key may comprise an identification of the original file. The system may further reclaim the data block in a storage system when the reference count is zero.

Abstract: Embodiments described herein are related to a method of scanning a B-tree. For example, a method comprises receiving a scan request to scan a B-tree having a plurality of levels, each level comprising one or more nodes, wherein for each of one or more levels of the plurality of levels, nodes are grouped into groups, where nodes of any given group are stored across sequential disk blocks. The method further comprises generating a queue for each level of the B-tree. For each queue, the method further comprises loading into memory a next group of nodes based upon determining a storage location of a node of the next group of nodes.

Abstract: The present disclosure provides techniques for deallocating previously allocated storage blocks. The techniques include obtaining a list of chunk IDs to analyze, choosing a chunk ID, and determining the storage blocks spanned by the chunk corresponding to the chosen chunk ID. The technique further includes determining whether any file references any storage blocks spanned by the chunk. The determining may be performed by comparing an internal reference count to a total reference count, where the internal reference count is the number of reference to the storage block by a chunk ID data structure. If no files reference any of the storage blocks spanned by the chunk, then all the storage blocks of the chunk can be deallocated.

Abstract: Optimizing file access includes a process for identifying a file access event for a first accessed file, and incrementing a first access counter in an access list in a memory, which also includes access counters for other accessed files. The process further includes exporting the first access counter to a performance monitoring dashboard, or exporting to a storage allocator and, based on the value, moving the first accessed file between a first storage and a second storage. The process also includes determining whether the value of the first access counter meets a first threshold, or a sum of values of the access counters for the other accessed files meets a second threshold. Based on meeting the first threshold or meeting the second threshold, the process includes persisting the access counters on a storage media. The access counters also provide security monitoring (e.g., identifying excessive file access).