Emc Corporation

Orit Levin Michael

Adnan Sahin

Amnon Naamad

Sachin More

Ron Arnan

Tao Kai Lam

Techniques and criteria are used in connection with promoting a slot within a cache in the form of a replacement queue. A cache slot may be promoted based on an inequality that considers the following criteria: probability of losing a cache hit, gaining a cache hit, and the price or cost associated with promoting a slot. The foregoing criteria may be used in accordance with a predetermined promotion policy when the replacement queue is in a locked state and an unlocked state, or only when the replacement queue is in a locked state. Different costs may be associated with the state of the replacement queue as locked or unlocked as the replacement queue may be locked in connection with operations that are performed on the replacement queue. The cost associated with a locked replacement queue may be different than the cost associated with an unlocked replacement queue. Different thresholds and values associated with the foregoing criteria may be specified as dynamic system parameters.

Cache slot promotion in a replacement queue cache using determinations of probabilities and costs

Described are techniques used in connection with determining one or more pairs of logical volumes (LVs) to increase the performance of storage devices by swapping these LVs. Future performance of the anticipated potential LV swap is determined in accordance with past performance data collected prior to actually performing the swap. Data is gathered for a first arrangement of data storage devices for a period of time. A proposed modification to the first arrangement, such as swapping LVs of data on one or more storage devices, is produced. A performance estimation is produced using past performance data for the one or more pairs of proposed LV swap candidates. The search for pairs of LV candidates is determined using an iterative technique in which earlier iterations attempt to produce candidates from a smaller, more focused pool of possible LVs. The pool of LVs is expanded upon subsequent iterations if earlier iterations using heuristics providing for a more focused search are unsuccessful.

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Newton, MA, United States of America

Orit Levin Michael