Dell Products Inc.

Karl David Schubert

William Price Dawkins

Stephen Gouze Luning

A method for masking logical storage devices from a host on a storage area network and a storage controller and storage system for using such a method are disclosed. The method includes receiving instructions for associating a subset of a plurality of logical storage devices with a particular host. A request from the particular host is received. The request includes a request for identification of available logical storage devices. The request is responded to by identifying the subset of logical storage devices as available.

Method for storage device masking in a storage area network and storage controller and storage subsystem for using such a method

A system and method for replacing cached data for a computer system utilizing one or more storage devices is disclosed. The storage devices are divided into a plurality of areas or bins. Each bin is preferably the same size. A Window Access Table (WAT) is an array stored in memory that contains all the time windows for each bin. Each time window holds a frequency value corresponding to the number of times the bin has been accessed during the time period corresponding to that time window. A hot spot algorithm is used to calculate a hot spot value hsf(x) for each bin based on its associated frequency values listed in the WAT. The hot spot algorithm uses scaling coefficients to weight the frequency values based on the time window. Each line in cache will therefore have an associated bin for which a hot spot value hsf(x) has been calculated. This data may be stored in a hot spot table. When data is retrieved from a storage in response to a cache miss, the memory controller will compare the hot spot value hsf(a) of the bin associated with the new data to the lowest hot spot value hsf(z) in the hot spot table. If hsf(z) is greater than hsf(a), then this indicates that bin (z), the bin with the lowest hot spot value is accessed more frequently than bin (a), the bin containing the retrieved data. Thus if hsf(z) is greater than hsf(a), then the cache line containing data from bin (z) will not be replaced. If hsf(a) is greater than hsf(z) then the new data from bin (a) will replace the cached data from bin (z).

System and method for time window access frequency based caching for memory controllers

A system and method for replacing cached data for a computer system utilizing one or more storage devices is disclosed. The storage devices are divided into a plurality of areas or bins. Each bin is preferably the same size. A Bin Access Table (BAT) is an array stored in memory that contains a frequency value for each bin corresponding to the number of times that the bin has been accessed during a predetermined time period. The BAT also contains a time stamp for each bin corresponding to the time that the bin was last accessed. A hot spot algorithm is used to calculate a hot spot factor or value hsf(x) for each bin based on its associated frequency value listed in the BAT. The frequency values may be weighted based on the time the bin was last accessed. Each line in cache will therefore correspond to a specific bin for which a time weighted hotspot factor hsf(x) has been calculated. These time weighted hot spot values are be stored in a hot spot table. When data is retrieved from a storage in response to a cache miss, a memory controller, such as a processor or RAID controller, will compare the hotspot factor hsf(a) of the bin associated with the new data to the lowest time weighted hotspot factor hsf(z) in the hot spot table. If the time weighted hsf(z) is greater than hsf(a), then this indicates that bin (z), the bin with the lowest time weighted hotspot factor, is accessed more frequently than bin (a), the bin containing the retrieved data. Thus if the time weighted hsf(z) is greater than hsf(a), then the cache line containing data from bin (z) will not be replaced. If hsf(a) is greater than the time weighted hsf(z) then the new data will replace the cached data from bin (z). The BAT table is updated after the I/O access.

System and method for time weighted access frequency based caching for memory controllers

A system and method for shared storage in a computer networking environment are provided. The system includes a fabric and a server coupled to the fabric. The server is operable to be coupled to a computer network and receive data from the network. The system further includes a physical storage device coupled to the fabric. The physical storage device is operable to store data received from the network. The system further includes a bridge coupled to the fabric and a dedicated backup storage device coupled to the bridge. The dedicated backup storage device is operable to store data received from the physical storage device.

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Austin, TX, United States of America

Karl David Schubert