Emc Corporation

Victoria Dubrovsky

Ruben Michel

Eitan Bachmat

Tao Kai Lam

David W DesRoches

Yuval Ofek

Avinoam Zakai

Ron Arnan

Shai Bar-Nefy

Moshe Schreiber

Described are techniques for performing compression and decompression of statistical data. This data may be used in connection with performing optimizations. A delta value for each statistic is determined representing a difference between a current value and a previous value. Delta values are stored in a statistics table in a compressed form using a monotonic compression scheme. Small tables are used to determine decompressed values estimating the observed values. Statistical information is stored and represented in a statistics table and an events table. Statistical information is selectively fetched and loaded into memory from a storage device. Indexing techniques are used to force physical continuity of the rows of the statistics table on a storage device in accordance with a specified retrieval order.

Optimizer improved statistics collection

Described are techniques for performing compression and decompression of statistical data. This data may be used in connection with performing optimizations. A delta value for each statistic is determined representing a difference between a current value and a previous value. Delta values are stored in a statistics table in a compressed form using a monotonic compression scheme. Small tables are used to determine decompressed values estimating the observed values when information is retrieved for use to within a predetermined relative error. Statistical information is stored and represented in a statistics table and an events table. Statistical information is selectively fetched and loaded into memory from a storage device. Indexing techniques are used to force physical continuity rows of the tables in accordance with a specified retrieval order.

Optimizer improved data compression

Load balancing of activities on physical disk storage devices is accomplished by monitoring reading and writing operations to blocks of contiguous storage locations on the physical disk storage devices. A list of exchangeable pairs of blocks is developed based on size and function. Statistics accumulated over an interval are then used to obtain access activity values for each block and each physical disk drive. A statistical analysis leads to a selection of one block pair. After testing to determine any adverse effect of making that change, the exchange is made to more evenly distribute the loading on individual physical disk storage devices.

Load balancing on disk array storage device

Load balancing of activities on physical disk storage devices is accomplished by monitoring reading and writing operations to blocks of contiguous storage locations on the physical disk storage devices. Statistics accumulated over an interval are then used to obtain access activity values for each block and each physical disk drive. A method is disclosed for efficiently generating disk access time based upon these statistics.

Method for analyzing disk seek times in a disk array storage device

A process performs an intra-disk swap. The process includes finding a set of values indicative of access loads of new states of a disk. Each new state is produced from a current state of the disk by hypothetically swapping a pair of physical storage volumes of the disk. The process also includes performing the swap of a pair of physical storage volumes based on the value of the access load of the new state produced by hypothetically swapping the pair.

Intra-disk swapping of data storage volumes

A method balances workloads of storage devices of a storage subsystem. The method includes reading a mailbox to obtain control parameters and collecting historical data on numbers of accesses to storage volumes of the storage devices. The control parameters are written in the mailbox by host devices. The method also includes selecting data swaps that lead to better balanced workloads for storage devices based on the historical data. The act of selecting and/or the act of collecting being initialized by the control parameters.

Mailbox for controlling storage subsystem reconfigurations

Load balancing of activities on physical disk storage devices is accomplished by monitoring reading and writing operations to blocks of contiguous storage locations on the physical disk storage devices. A list of exchangeable pairs of blocks is developed based on size and function. Statistics accumulated over an interval are then used to obtain access activity values for each block and each physical disk drive. These activities are represented as disk seek, latency and data transfer times. A statistical analysis leads to a selection of one block pair. After testing to determine any adverse effect of making that change, the exchange is made to more evenly distribute the loading on individual physical disk storage devices.

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Westboro, MA, United States of America

Victoria Dubrovsky