Dell Products Inc.

Emc IP Holding Company LLC

David Bernard

Vamsi K Vankamamidi

Shari Vietry

Vladimir Shveidel

Jason E Raff

Philippe Armangau

Alan Lee Taylor

Nagapraveen Veeravenkata Seela

Bar David

Svetlana Kronrod

Mayank Ajmera

Techniques for tracking incoming writes and snap creation/deletion in memory to improve asynchronous replication and support lower RPOs. In the techniques, a storage system uses its data cache to receive data specified in write requests issued by storage clients, while dedicating an amount of the cache memory to track and record offsets/lengths of writes directed to source volumes. At the end of each replication interval, the storage system obtains a list of the recorded offsets/lengths for each source volume, identifies and reads areas of the source volume that were written to during the replication interval using the list, and replicates data from the identified areas to a destination volume. Because the list of recorded offsets/lengths of incoming writes for the source volume is compiled and available from volatile cache memory, it can be generated and accessed very quickly using reduced processing/memory resources, allowing for lower RPOs in asynchronous replication processes.

Tracking writes and snapshot creation/deletion in memory to improve asynchronous replication performance and support lower recovery point objectives (RPOs)

Techniques can include: receiving from a component a bufferless read request to read data of a storage object; opening a first transaction; acquiring locks of data pages including the read data; locking cache pages; storing the read data in the cache pages; sending to the component a notification identifying references, pointers or addresses of the cache pages storing the read data; responsive to receiving the notification, the first component performing one or more operations including directly accessing the first data from the cache pages using the references, pointers or addresses; and responsive to successfully completing the one or more operations, performing second processing including: releasing or unlocking the set of one or more cache pages storing the first data; releasing the one or more locks of the one or more data pages including the first data; and closing the first transaction.

Replication techniques with data copy avoidance

A method, computer program product, and computer system for acquiring, by a first node, local locks of the first node associated with a metadata log transaction, wherein the first node acquires the local locks of the first node prior to sending a commit message to a second node. The second node may acquire local locks of the second node associated with the metadata log transaction, wherein the second node acquires the local locks of the second node based upon, at least in part, receiving the commit message from the first node.

System and method for consistent metadata access based on local locks semantics in a multi-node cluster

Processing can be performed to persistently record, in a log, a write I/O that writes first data to a target logical address. The processing can include: allocating storage for a first page buffer (PB) located at offsets in a PB pool of non-volatile storage of the log; enqueuing a request to an aggregation queue to persistently store the first data to the first PB of the log, wherein the request identifies the offsets of the PB pool of non-volatile storage which correspond to the first PB; and integrating the request into the aggregation queue. Integrating can include: determining whether a contiguous segment of the offsets of the request is adjacent to a second contiguous segment of the aggregation queue; and responsive to determining the contiguous segment is adjacent to the second contiguous segment, merging the first and second contiguous segments and generating an aggregated continuous segment.

Coalescing logged operations

A method of operating a storage appliance is provided. The method includes (a) in response to the appliance receiving a first command to perform a first storage operation on a first plurality of blocks, storing a command record for each block of the first plurality in a cache, each command record respectively indicating an address of that block; (b) upon flushing the command record for each block of the first plurality from the cache to persistent storage, storing data of that block at its indicated address; (c) in response to the storage appliance receiving a second command to perform a second storage operation on a second plurality of blocks, storing, in the cache, an aggregated command record that indicates the second storage operation and an address range of the second plurality, the second storage operation representing an identical change to all blocks of the second plurality; and (d) upon flushing the aggregated command record from the cache to the persistent storage, performing the storage operation indicated by the aggregated command record over the address range indicated by the aggregated command record.

Selectively processing storage commands at different granularities based on command types

Techniques for in-band locking of extents containing multiple pages of shared non-volatile data storage are disclosed in which inter-node lock request messages indicate both an individual page for which a lock is requested and the multi-page extent that contains that page. A page lock or an extent lock is granted to the requesting node based on the time since the last access to the extent by the node to which the request was sent. A generation number may be maintained in each node and stored in the per-extent lock table entries and per-page lock table entries such that pages accessed by a node within an extent while the extent is in extent-locked access mode may subsequently be accessed by the node during a page-locked access mode for the extent occurring after the extent-locked access mode ends based on page locks created by the node during the extent-locked access mode.

Growing community of inventors

Westford, MA, United States of America

David Bernard