Netapp, Inc.

Oracle America, Inc.

Joseph Russell Blount

William Patrick Delaney

Charles D Binford

Joseph Moore

Randolph Wesley Sterns

Keith Moyer

Rodney A Dekoning

Reid A Kaufmann

Stacy Lee Maydew

Jeff Stilger

Reid Kaufmann

The application relates to writing arbitrarily sized data extents using in-line descriptors, such as headers or footers, into physical blocks to describe the data extents in those physical blocks. Some data extents may be smaller than the size of a physical block, and some data extents may be larger than the size of a physical block. A given physical block therefore includes an in-line descriptor for a data extent in that block, indicating that the data extent starts within that block and also an offset from the beginning of the block to where the data extent starts. The in-line descriptor is included within the block so that when the block is read both the data and the descriptor are read, thereby eliminating performance penalty for reading the descriptor information.

Systems, methods, and computer readable media providing arbitrary sizing of data extents

A method includes: storing a first data extent on a physical medium, wherein the physical medium is divided into a plurality of storage blocks, wherein each of the storage blocks has a size that is different than a size of the first data extent, further wherein the first data extent is stored to a first block of the plurality of storage blocks; generating a descriptor for the first data extent, wherein the descriptor indicates that the first data extent starts within the first block of the plurality of blocks and indicates an offset from the beginning of the first block at which the first data extent starts; and storing the descriptor within the first block.

A system shares I/O load between controllers in a high availability system. For writes, a controller determines based on one or more factors which controller will flush batches of data from write-back cache to better distribute the I/O burden. The determination occurs after the local storage controller caches the data, mirrors it, and confirms write complete to the host. Once it is determined which storage controller will flush the cache, the flush occurs and the corresponding metadata at a second layer of indirection is updated by that determined storage controller (whether or not it is identified as the owner of the corresponding volume to the host, while the volume owner updates metadata at a first layer of indirection). For a host read, the controller that owns the volume accesses the metadata from whichever controller(s) flushed the data previously and reads the data, regardless of which controller had performed the flush.

Read and write load sharing in a storage array via partitioned ownership of data blocks

A system and method for improving storage system performance by reducing or avoiding load spike amplification when performing garbage collection is disclosed. A storage controller in a storage system tracks system load including write load and read load, as well as available free segments. The storage controller uses these tracked values as inputs and, with these inputs, generates a garbage collection rate. Where read load is included, a scaled portion of the read load is taken into consideration so that, as the number of free segments nears the minimum amount desired and to prevent garbage collecting too slowly, the read load is gradually excluded from the garbage collection rate determination. The garbage collection rate is therefore responsive to system load so that, in times of high system load, the rate reduces as much as is safe so that the write load takes priority with computing resources of the storage controller.

Garbage collection pacing in a storage system

A method, a computing device, and a non-transitory machine-readable medium for allocating data compression activities in a storage system are provided. A method includes tracking, by a storage controller, computing resources corresponding to a storage server. The storage controller processes one or more host read requests to access data requested by one or more hosts, the processing of the one or more host read requests including decompressing the data requested by the one or more hosts from the storage server and providing the decompressed data to the one or more hosts. The storage controller determines an amount of available computing resources after processing the one or more host read requests. Based on the amount of available computing resources, the storage controller performs inline compression of a first portion of host write requests and background compression of a second portion of the host write requests.

Systems and methods for allocating data compression activities in a storage system

A system for tracking metadata changes and recovering from system interruptions. With host I/O, corresponding metadata incremental changes are aggregated and stored in a write-ahead log before being performed to their in-memory buffers. As those buffers are flushed, checkpoints are created and stored in the log. As the log wraps to the start, older entries are overwritten after they are freed from any remaining dependencies by newer checkpoints. If metadata entities have not created new checkpoints, they are instructed to in order to free up space for new aggregated batches and checkpoints. After an interruption, the wrap point is located in the log. From the wrap point, the log is scanned backwards to provide checkpoints to metadata entities. The log is then scanned forwards to perform changes specified by aggregated batches. The metadata entities' volatile memory states are recovered to what they were before the interruption.

Write-ahead log maintenance and recovery

A system and method for metadata storage includes use of a storage controller to receive a write operation from a host, create a metadata entry for storing metadata associated with data written by the write operation, and store the metadata entry into a metadata store. The metadata store includes a plurality of active partitions, a plurality of inactive partitions, and a queue identifying locations in the active partitions where the metadata entry may be stored. The metadata store is further used to access data written to one or more storage devices. Storing the metadata entry into the metadata store includes popping a first location from the queue, identifying a first active partition from the active partitions based on the first location, and storing the metadata entry in the first active partition. In some embodiments, each of the active partitions may be organized into two or more tiers.

Systems and methods for reducing write tax, memory usage, and trapped capacity in metadata storage

A method for mapping a first address space to a second address space is provided. In some embodiments, the method includes creating a first array of lookup entries and one or more second arrays of metadata entries for maintaining an ordering among the lookup entries using a tree structure. Each of the metadata entries includes one or more data index values identifying a corresponding one of the lookup entries by its position in the first array and one or more metadata index values identifying a corresponding one of the metadata entries by its position in one of the one or more second arrays. The method further includes receiving a request including a lookup value, traversing the tree structure to locate a lookup entry corresponding to the lookup value, and when the lookup value is located among the lookup entries, using the located lookup entry to process the request.

Memory efficient lookup structure

Methods and systems for storing data at a storage device of a storage system are provided. The data is first temporarily stored at a first write cache and an input/output request for a persistence storage device used as a second write cache is generated, when an I/O request size including the received data has reached a threshold value. The data from the first cache is transferred to the persistence storage device and a recovery control block with a location of the data stored at the persistence storage device is updated. An entry is added to a linked list that is used to track valid data stored at the persistence storage device and then the data is transferred from the persistence storage device to the storage device of the storage system.

Methods and systems for using a write cache in a storage system

Systems and techniques for recovering a storage array are disclosed. These systems and techniques include determining a size corresponding to a storage stripe of the storage array. Pieces assigned to the storage stripe are identified. A storage configuration corresponding to the pieces assigned to the storage stripe is detected. Ordinal information and parity information are determined corresponding to the pieces assigned to the storage stripe. The size determined corresponding to the storage stripe, identification of the pieces assigned to the storage stripe, the storage configuration, the ordinal information, and the parity information is stored in a data store to reconstruct lost or corrupted metadata corresponding to the storage array.

Growing community of inventors

Andover, KS, United States of America

Joseph Russell Blount