Emc Corporation

Emc IP Holding Company LLC

Chris Seibel

Philippe Armangau

Jean-Pierre Bono

Xiangping Chen

Yubing Wang

Henry Austin Spang, Iv

David John Agans

John A Hassey

A technique for managing storage in a data storage system includes ingesting host data into a data log backed by pages in a cache. The host data are addressed to specified locations in a data object stored in persistent storage devices. When mapping pages in cache to respective target locations in the persistent storage devices, a flag is selectively asserted to indicate whether there is contiguous free space at the target locations. The cache responds to the flag by delaying flushing of flagged pages, which provides more time for the cache to aggregate pages that map to contiguous free space. Meanwhile, pages that are not flagged can be flushed more quickly, enabling the cache to operate efficiently even though flushing of some pages is delayed.

Selectively delaying cache flushing to promote write efficiency

A technique for managing resources on a storage array having multiple CPU cores releases share locks on a resource by decrementing share lock counters associated with the CPU cores that release the share locks, regardless of whether these are the same as the CPU cores that acquired the share locks. As each CPU core changes its own share lock counter, cache trashing caused by changing share lock counters associated with other CPU cores can be avoided.

Managing read/write locks for multiple CPU cores for efficient access to storage array resources

A technique of managing data fragmentation is performed in a data storage apparatus. The technique involves receiving an indication that IO access to particular data stored within a memory space has exceeded a predefined threshold level. The technique further involves performing, in response to the indication, a defragmentation evaluation operation. The technique further involves performing a set of data movement operations which moves the particular data from a first set of storage locations of the memory space to a second set of storage locations of the memory space to improve defragmentation of the particular data when a result of the defragmentation evaluation operation has a first value. The technique further involves maintaining the particular data at the first set of storage locations of the memory space when the result of the defragmentation evaluation operation has a second value which is different than the first value.

Selective defragmentation based on IO hot spots

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Walpole, MA, United States of America

Chris Seibel