Abstract: Systems and methods enabling search of a repository for the location of data that is similar to input data, using a defined measure of similarity, in a time that is independent of the size of the repository and linear in a size of the input data, and a space that is proportional to a small fraction of the size of the repository. The similar data segments thus located are further analyzed to determine their common (identical) data sections, regardless of the order and position of the common data sections in the repository and input, and in a time that is linear in the segment size and in constant space.

Abstract: A method for providing data indicative of the performance of a competing algorithm and an incumbent algorithm includes evaluating an incumbent-algorithm score indicative of a performance of an incumbent algorithm. The performance of a competing algorithm executing in place of the incumbent algorithm is then simulated. On the basis of the simulation, a competing-algorithm score predictive of a performance of the competing algorithm is evaluated. These scores are then provided to an output device.

Abstract: A system efficiently determines of the likely effectiveness of the cache memory for various cache memory sizes, based on a prediction of the likely cache miss rate, the prediction being based on operational statistics which are gathered during actual use of the cache memory over one or more time periods, and based on a variety of cache management methodologies. Based on the prediction, the operator or the system can facilitate increasing or decreasing the size of the cache memory, or maintaining the cache memory at its then-current size. The system determines the cache memory's read miss rate from statistics that are collected during use of the cache memory over an arbitrary time interval, including statistics concerning the file information retrieval activity and the extent of activity per unit time for system.

Abstract: Systems and methods enabling search of a repository for the location of data that is similar to input data, using a defined measure of similarity, in a time that is independent of the size of the repository and linear in a size of the input data, and a space that is proportional to a small fraction of the size of the repository. Additionally, remote operations are accomplished with significantly reduced system bandwidth by implementing remote differencing operations.

Abstract: Systems and methods enabling search of a repository for the location of data that is similar to input data, using a defined measure of similarity, in a time that is independent of the size of the repository and linear in a size of the input data, and a space that is proportional to a small fraction of the size of the repository. The similar data segments thus located are further analyzed to determine their common (identical) data sections, regardless of the order and position of the common data sections in the repository and input, and in a time that is linear in the segment size and in constant space.

Abstract: Optimizing performance of physical disk drives in a disk array storage device with a plurality of logical volumes is accomplished by accumulating statistics over an interval to select two logical volumes for an exchange. After testing to determine any adverse effect of making that change, the exchange occurs to more evenly distribute the loading on individual physical disk storage devices. One set of statistics, seek time, is obtained by combining estimated disk access information and an interpolated seek time obtained from a template that stores characteristics seek times among different pairs of segments that define a physical disk device independently of a logical volume configuration.

Abstract: Optimizing performance of physical disk drives in a disk array storage device with a plurality of logical volumes is accomplished by accumulating statistics over an interval to select two logical volumes for an exchange. After testing to determine any adverse effect of making that change, the exchange occurs to more evenly distribute the loading on individual physical disk storage devices. One set of statistics, seek time, is obtained by combining estimated disk access information and an interpolated seek time obtained from a template that stores characteristics seek times among different pairs of segments that define a physical disk device independently of a logical volume configuration.

Abstract: A data storage device is described that includes a plurality of host interface units, a plurality of disk interface units, and a plurality of disk drive units each coupled to one of the disk interface units. The host interface units may be coupled to one or more external host systems for performing a data operation to a disk drive system. A disk drive unit includes a controller with an onboard memory subdivided into two sections in which one of the sections may be used in connection with performing caching operations of data. The data cached may be from the disk platter associated with the disk drive unit, or, the data cached in the section may also be from another disk drive unit different from the one associated with the disk drive unit in which the section is included. Commands are generated for performing data caching operations to the section of the onboard memory.

Abstract: A process that swaps physical storage volumes. The process performs a number of simple arithmetic operations to find a seek time for B new states of a disk. The number is of order B. Each new state is related to a current state of the disk by a swap with a selected external storage volume. The process also includes swapping one of the storage volumes of the disk with the selected storage volume in response to determining that the state produced by the swap has a smallest seek or access time among the new states.

Abstract: The invention relates generally to mass storage systems, and in particular to mass storage systems in which stored logical volumes are duplicated in mirrored form. The system includes a method for dynamically maximizing separation of said logical volumes by adjusting the mirror service policy for a disk drive system. Statistics are periodically collected describing the reading and writing of data to mirrored logical volumes of the system in successive time periods and, from time to time, based upon the collected statistics, activity levels for the logical volumes are determined. A matching algorithm, weighted or unweighted, maximizes separation of the logical volumes and minimizes average physical drive seek times. In particular, the system takes into account activity levels at the physical devices and results in more efficient accessing of logical volume pairs as well as a better balance or loading of logical volumes.

Abstract: Load balancing of activities on physical disk storage devices is accomplished by monitoring reading and writing operations to logical volumes on the physical disk storage devices. A list of exchangeable pairs of logical volumes is developed based on size and function. Statistics accumulated over an interval are then used to obtain access activity values for each logical volume and each physical disk drive. A statistical analysis selects one logical volume 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A process determines a seek time of an access head of a physical storage disk. The process includes collecting statistical access data on physical storage volumes served by the access head and determining seek times for a set of reference head travel time functions. Each function depends on distances between pairs of the physical storage volumes. The process also includes performing a sum of the determined seek times. Each term of the sum is weighted by an expansion coefficient of a travel time function of the access head with respect to the set of reference head travel time functions.

Abstract: A mechanism for adjusting seek activity in a data storage system of physical devices having mirrored logical volumes is presented. Statistics describing at least reading data from the mirrored volumes during successive time periods are collected. From the collected statistics an activity level associated with each of the mirrored logical volumes is determined. Seek activity values for the physical devices are computed based on the activity levels associated with the logical volumes stored on each of the physical devices. The computed seek activity values relate a physical device seek activity to the activity level associated with, and distance between, the mirrored logical volumes residing the physical devices. The computed seek values are used to minimize seek activity for non-mirrored ones of the physical devices.

Abstract: 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.

Abstract: Load balancing of activities on physical disk storage devices is accomplished by monitoring reading and writing operations to logical volumes on the physical disk storage devices. A list of exchangeable pairs of logical volumes is developed based on size and function. Statistics accumulated over an interval are then used to obtain access activity values for each logical volume and each physical disk drive. A statistical analysis selects one logical volume 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.

Abstract: 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.

Abstract: 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.