Storage system

Abstract

A storage system and a method for storing a data segment, a storage capacity manager and a method for managing a capacity of a storage unit, and a storage tier relocation manager and a method for relocating a data segment. The storage system includes at least two storage tiers, an access pattern evaluator, a classification unit, a selector, and logic. The storage capacitor manager includes a monitoring unit and capacity managing unit. The storage tier relocation manager includes a target storage tier, the data segment relocated to the target storage tier, and a protection measure.

What is claimed is: 
     
         1 . A storage system, comprising:
 a storage unit including at least two storage tiers;   an access pattern evaluator configured to provide information about a frequency at which data segments stored in at least one of the at least two storage tiers are accessed;   a classification unit configured to assign at least one out of a set of at least two relevance classes to a data segment received for storing in the storage unit dependent on information included in the data segment;   a selector configured to determine a storage tier out of the at least two storage tiers for storing the classified data segment to, dependent on at least access frequency information provided by the access pattern evaluator for data segments in the same relevance class, and configured to determine a level of protection for the classified data segment dependent on at least the relevance class assigned; and   logic for storing the classified data segment including the assigned relevance class to the determined storage tier and according to the determined level of protection.   
     
     
         2 . The storage system according to  claim 1 ,
 wherein the classification unit comprises a set of event detectors with each event detector of the set being configured to detect a different event in the data segment received for storing; and   wherein the classification unit comprises a set of classifiers, each classifier being assigned to a different one of the event detectors, and each classifier of the set being configured to assign at least one relevance class pre-selected from the set of relevance classes for the event to be detected by the assigned event detector.   
     
     
         3 . The storage system according to  claim 1 , comprising
 a real-time data processing unit for real-time processing of input data segments and providing a sequence of data segments for storing.   
     
     
         4 . The storage system according to  claim 1 ,
 wherein the selector is configured to determine the storage tier for the classified data segment dependent on the access frequency information provided by the access pattern evaluator for data segments in the same relevance class, and dependent on the relevance class assigned; and   wherein the selector is configured to determine the level of protection for the classified data segment dependent on the relevance class assigned, and dependent on the access frequency information provided by the access pattern evaluator for data segments in the same relevance class.   
     
     
         5 . The storage system according to  claim 1 ,
 wherein the selector is configured to determine a redundancy level for the classified data segment dependent on the determined protection level and the determined storage tier, the redundancy level specifying a number of copies of the classified data segment to be stored in the storage unit, and in particular specifying a number of copies of the classified data segment to be stored in which storage tier of the storage unit; and   wherein the logic is configured to store copies of the classified data segment in the at least one storage tier according to the determined level of redundancy.   
     
     
         6 . The storage system according to  claim 1 ,
 wherein the selector is configured to determine at least one of an error correction codes and an erasure code to be applied to the classified data segment dependent on the determined protection level and dependent on the determined storage tier; and   wherein the logic is configured to store the classified data segment with at least one of the determined error correction codes and determined erasure code in the storage unit.   
     
     
         7 . Method for storing a data segment in a storage tier of a storage unit including at least two storage tiers, comprising:
 assigning at least one out of a set of at least two relevance classes to the data segment dependent on information included in the data segment;   receiving information about a frequency at which data segments stored in at least one of the at least two storage tiers are accessed;   determining a storage tier out of the at least two storage tiers for storing the classified data segment to dependent on at least access frequency information received for data segments in the same relevance class;   determining a level of protection for the classified data segment dependent on at least the relevance class assigned; and   storing the classified data segment including the assigned relevance class to the determined storage tier and according to the determined level of protection.   
     
     
         8 . A storage tier relocation manager for relocating a data segment presently stored in a storage tier of a storage unit with at least two storage tiers the data segment having assigned a protection level out of a set of protection levels, the storage tier relocation manager being configured to:
 determine a target storage tier for the data segment dependent on access frequency information received for one or more of the data segment or a relevance class the data segment is assigned to;   relocate the data segment to the target storage tier if the target storage tier is different from the present storage tier; and   in case of a relocation, apply a protection measure suitable for achieving the assigned protection level.   
     
     
         9 . The storage tier relocation manager according to  claim 8 , being configured to in case of a relocation apply the protection measure by selecting at least one of:
 a redundancy level specifying a number of copies of the data segment to be stored in at least one of the target storage tiers and a non-target storage tiers;   an error correction code to be applied to the data segment;   and an erasure code to be applied to the data segment; and   store the data segment in the storage unit according to the selected of at least one of the redundancy levels, the error correction code and the erasure code.   
     
     
         10 . Method for relocating a data segment presently stored in a storage tier of a storage unit with at least two storage tiers, the data segment having assigned a protection level out of a set of protection levels, comprising:
 determining a target storage tier for the data segment dependent on access frequency information received for at least one of the data segments or a relevance class the data segment is assigned to;   relocating the data segment to the target storage tier if the target storage tier is different from the present storage tier; and   applying a protection measure suitable for achieving the assigned protection level in case of a relocation.   
     
     
         11 . A storage capacity manager for a storage system comprising a storage unit for storing data segments having at least one relevance class assigned per data segment, the storage capacity manager comprising:
 a monitoring unit for determining if a utilization of the storage unit fulfils a criterion; and   a capacity managing unit for, in response to the utilization of the storage unit fulfilling the criterion, selecting at least one data segment stored in the storage unit for one of a deletion thereof or a deletion of a copy thereof at least dependent on the at least one relevance class assigned.   
     
     
         12 . The storage capacity manager according to  claim 11 ,
 wherein the storage capacity manager is configured to manage a storage unit comprising at least two storage tiers;   wherein the monitoring unit is configured to determine if the utilization of at least one of the at least two storage tiers fulfils the criterion; and   wherein the capacity managing unit is configured to, in response to the utilization of at least one storage tier fulfilling the criterion, selecting the at least one data segment stored in this storage tier for one of a deletion thereof or a deletion of a copy thereof in the same storage tier or in a different storage tier.   
     
     
         13 . The storage capacity manager according to  claim 11 ,
 wherein the monitoring unit is configured to determine if the utilization of the storage unit falls below a capacity threshold; and   wherein the capacity managing unit is configured to select the at least one data segment in response to the utilization of the storage unit falling below the capacity threshold.   
     
     
         14 . The storage capacity manager according to  claim 11 , wherein the capacity managing unit is configured to:
 suggest the at least one selected data segment for deletion or deletion of a copy thereof;   suggest the at least one selected data segment for deletion or deletion of a copy thereof and delete the at least one selected data segment or a copy thereof in response to a user confirmation;   delete the at least one selected segment or copies thereof; or   a combination thereof.   
     
     
         15 . The storage capacity manager according to  claim 11 ,
 wherein the capacity managing unit is configured to assign a retention class out of a set of retention classes to the data segments in the storage unit, each retention class out of the set indicating a measure for retaining the assigned data segment in the storage unit, the assignment of the retention class to a data segment being made dependent on the relevance class assigned to the data segment; and   wherein the capacity managing unit is configured to select the at least one data segment for one of a deletion thereof or a deletion of a copy thereof dependent on the retention class assigned.   
     
     
         16 . The storage capacity manager according to  claim 15 ,
 wherein the capacity managing unit is configured to select the at least one data segment for deletion if the corresponding data segment is within a number of n data segments showing the lowest retention classes assigned.   
     
     
         17 . The storage capacity manager according to  claim 15 ,
 wherein the capacity managing unit is configured to manage the storage of data segments in a variable number of copies; and   wherein the capacity managing unit is configured to select the at least one data segment for deleting at least one copy thereof if the corresponding retention class is below a retention threshold.   
     
     
         18 . The storage capacity manager according  claim 15 , wherein the capacity managing unit is configured to determine the retention class to assign to a data segment in addition dependent on at least one of:
 an age of the data segment;   access frequency information for the data segment or for the relevance class the data segment is assigned to;   a persistence index; and   a storage capacity available in at least one of the other storage tiers in case of a tiered storage unit.   
     
     
         19 . Method for managing a capacity of a storage unit for storing data segments having at least one relevance class assigned per data segment, the method comprising:
 determining if a utilization of the storage unit fulfils a criterion;   responding to the utilization of the storage unit fulfilling the criterion; and   selecting at least one data segment stored in the storage unit for one of a deletion thereof or a deletion of a copy thereof at least dependent on the relevance class assigned.   
     
     
         20 . A non-transitory computer program product comprising a computer readable medium having computer readable program code embodied therewith, wherein the computer readable program code is configured to perform a method according to  claim 19 .