Emc IP Holding Company LLC

Emc Corporation

Alexander Daniel

Philippe Armangau

Ajay Karri

Monica Chaudhary

Ye Zhang

Jean-Pierre Bono

William C Davenport

Yining Si

Qi Mao

Chao Zheng

Yaming Kuang

Ruijing Guo

Pu Wang

A technique for managing write requests in a data storage system checks whether newly-arriving data match previously-stored data that have been recorded in a deduplication database. If a match is found, the technique compares mapping metadata for the newly-arriving data with mapping metadata for the matching data. If both sets of metadata point to the same storage location, then the newly-arriving data is a same-data write and a new write to disk is avoided.

Applying deduplication digests to avoid same-data writes

A technique for managing data received into a cache operates in cycles. To process a current batch of compressed blocks during a current cache processing cycle, a storage system obtains a new mapping structure and a new segment of contiguous storage space. If the system can place some of the current batch of compressed blocks into previously-allocated space, the system does so and partially populates the new mapping structure with entries for mapping the other compressed blocks that were not placed. The system then asserts a hold on the new mapping structure, so that the mapping structure is retained in cache at the end of the current cache processing cycle, and more completely populates the new mapping structure with entries for other compressed blocks during a later cache processing cycle before releasing the hold.

Optimizing space utilization by retaining metadata in cache

A technique for writing data in a data storage system includes aggregating data received in a set of I/O requests into a batch that includes multiple extents of data. After compressing a current extent of the batch and determining that the compressed extent does not fit in a space where a previous version of the extent is stored, the technique performs a batch-relocate operation by gathering a set of mapping metadata for mapping each of the extents in the batch, identifying a set of holes indicated by the set of mapping metadata, and adding the holes to a batch-hole list. The technique then selects a hole, from the batch-hole list, which is big enough to accommodate the compressed extent, and places the compressed extent in the selected hole.

Relocating compressed extents using batch-hole list

A technique for writing data in a file system includes aggregating data received in a set of I/O requests into a batch that includes multiple extents of data. After compressing a current extent of the batch and determining that the compressed extent does not fit in a space where a previous version of the extent is stored, the technique performs an FS-relocate operation by accessing an F S-hole list provided for the file system and selecting a hole, from the FS-relocate list, which is large enough to accommodate the compressed extent. The technique then places the compressed extent in the selected hole.

Relocating compressed extents using file-system hole list

A method, computer program product, and computer system for instantiating, by a computing device, a slice-object associated with a slice when the slice-object is accessed. The slice-object is released to a slice object cache when accessing is complete. It is determined whether the slice is accessed within a threshold period of time. If the slice is accessed within the threshold period of time, the slice-object is retrieved from the slice-object cache. If the slice is not accessed within the threshold period of time, memory used for the slice-object is released.

Sparse volume management cache mechanism system and method

A technique manages data within a data storage apparatus having a cache of volatile memory and non-volatile storage. The technique involves receiving a set of write commands to write data to the non-volatile storage. The technique further involves acknowledging, in a write-back caching manner, completion of the set of write commands after the data reaches the cache of volatile memory and prior to the data reaching the non-volatile storage. The data includes host data as well as critical metadata. The technique further involves saving, after acknowledging completion of the set of write commands, the data from the cache of volatile memory to the non-volatile storage, the critical metadata being saved from the cache of volatile memory to the non-volatile storage at a quicker rate than that of the host data (i.e., accelerated synchronization of the critical metadata).

Accelerating synchronization of certain types of cached data

Techniques are described for copying data using a throttling mechanism to achieve a desired time delay. A request is received to copy a data portion from a source location of a first physical device to a target location of a second physical device. A desired average delay time is determined in accordance with a plurality of values including a throttle value affecting a rate at which data is copied from the source location to the target location. The request is partitioned into subrequests. The data portion is partitioned into a subportions. Each of the subrequests copies one of the subportions. The subrequests are performed whereby a time delay is introduced between at least two of the plurality of subrequests and whereby an average time delay with respect to each pair of consecutively issued subrequests is the desired average time delay.

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Westford, MA, United States of America

Alexander Daniel