Abstract: Described are techniques and criteria used in connection with cache management. The cache may be organized as a plurality of memory banks in which each memory bank includes a plurality of slots. Each memory bank has an associate control slot that includes groups of extents of tags. Each cache slot has a corresponding tag that includes a bit value indicating the availability of the associated cache slot, and a time stamp indicating the last time the data in the slot was used. The cache may be shared by multiple processors. Exclusive access of the cache slots is implemented using an atomic compare and swap instruction. The time stamp of slots in the cache may be adjusted to indicate ages of slots affecting the amount of time a particular portion of data remains in the cache.

Abstract: A method for estimating the fall through time of a cache includes maintaining local statistics associated with each data cache slot replaced by a processor, reading from a memory global statistics related to each data cache slot replaced by a plurality of processors, calculating new global statistics, and estimating a fall through time of the cache in response to the global statistics at a predetermined rate. When the global statistics are the result of at least a threshold number of data cache slots having been replaced, the new global statistics are calculated by weighting the global statistics by a factor of less than one and adding the weighted global statistics to the local statistics. When the global statistics are not the result of at least a threshold number of data cache slots having been replaced, the new global statistics are calculated by adding a time related to the lapsed time to a global sum value associated with the time stamp difference of the replaced data cache slots.

Abstract: Described are techniques used in connection with cache management. Data included in a cache slot is put “on parole” with a first cache hit while waiting for subsequent cache hits. If a subsequent hit is received to the cache slot, it remains in the cache for a longer time period than a slot having only a first cache hit. The cache may be organized as a plurality of memory banks of cache slots. Each memory bank has an associated control slot that includes groups of extents of tags. Each cache slot has a corresponding tag, and a time stamp. The time stamp of slots in the cache may be adjusted affecting the amount of time a particular portion of data remains in the cache.

Abstract: A method and apparatus for cache management in a data storage system is presented. A table with tags corresponding to cache slots in a cache memory is provided. A copy of the table is stored in a local buffer in response to a request for allocation of one of the cache slots. The locally buffered table is used to make the requested cache slot allocation. A set of control parameters associated with the locally buffered table is used to determine if the locally buffered table can be re-used for cache slot allocation in response to a subsequent request for cache slot allocation. User-selectable levels are provided to control the degree of locally buffered table re-use. The user-selectable levels determine which values of the control parameters are used.

Abstract: Described are various quality of service (QOS) parameters that may be used in characterizing device behavior in connection with a cache. A Partition parameter indicates which portions of available cache may used with data of an associated device. A Survival parameter indicates how long data of an associate device should remain in cache after use. A Linearity parameter indicates a likelihood factor that subsequent data tracks may be used such that this parameter may be used in determining whether to prefetch data. A Flush parameter indicates how long data should remain in cache after a write pending slot is returned to cache after being written out to the actual device. The QOS parameters may be included in configuration data. The QOS parameter values may be read and/or modified.

Abstract: An approach to archiving data that enables a client to back-up files to a server that is assigned by a client and periodically verify the most recent versions of the files are present on the server or restore backed-up files from the server to a workstations where a client resides.

Abstract: A debugger mechanism to support multiple active targets and efficient switching between multiple active targets, in particular, heterogeneous targets, in a multiprocessing environment.

Abstract: The cache arrangement includes a cache that may be organized as a plurality of memory banks in which each memory bank includes a plurality of slots. Each memory bank has an associated control slot that includes groups of extents of tags. Each cache slot has a corresponding tag that includes a bit value indicating the availability of the associated cache slot, and a time stamp indicating the last time the data in the slot was used. The cache may be shared by multiple processors. Exclusive access of the cache slots is implemented using an atomic compare and swap instruction. The time stamp of slots in the cache may be adjusted to indicate ages of slots affecting the amount of time a particular portion of data remains in the cache. Associated with each processor is a unique extent increment used to determine a next location for that particular processor when attempting to locate an available slot.

Abstract: The invention features a method and a system for selecting a slot within a memory unit, e.g., cache, for removal. The memory unit is accessible to a plurality of processors, and each slot in the memory unit has a corresponding entry in an age table. Each time when a processor examines one of the entries, an age value of the entry is increased. When the age value is above a maturity age, the corresponding slot becomes a removable slot. Each processor also maintains statistics to estimate the number of removable slots in the memory unit. According to the statistics, adjusts a maturity age associated with the processor dynamically and independently to control the number of removable slots. Accordingly, the number removable slots can be maintained at a pre-determined percentage relative to the total number of slots in the memory unit.