Storage system

Abstract

A method for storing a data segment in a storage tier of a storage unit comprising at least two storage tiers includes receiving the data segment to be stored including metadata; receiving metadata of data segments stored in the storage unit; and determining the storage tier to store the received data segment to and a protection level dependent on the metadata received and dependent on the metadata of the received data segment.

1 . A method for storing a data segment in a storage tier of a storage unit comprising at least two storage tiers, the method comprising:
 receiving the data segment to be stored including metadata;   receiving metadata of data segments stored in the storage unit; and   determining the storage tier to store the received data segment to and a protection level dependent on the metadata received and dependent on the metadata of the received data segment.   
     
     
         2 . The method of  claim 1 , wherein determining the storage tier and the protection level includes identifying a storage tier and a protection level at which a majority of data segments showing the same or similar metadata as the received data segment is stored. 
     
     
         3 . The method of  claim 1 , wherein:
 a relevance class out of a set of at least two relevance classes is assigned to the received data segment; and   the storage tier is determined for the received data segment dependent on the relevance class assigned to the received data segment.   
     
     
         4 . The method of  claim 3 , further comprising:
 determining information about a frequency at which data segments stored in one or more of the at least two storage tiers are accessed;   determining the storage tier for storing the received data segment to be 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.   
     
     
         5 . The method of  claim 1 , wherein:
 the metadata of a data segment comprises a set of variables; and   the set of variables includes one or more of: a user of the data segment, a size of the data segment, an access control list for the data segment, a time of generation of the data segment, a time of last modification of the data segment, a time of last access of the data segment, a location of the data segment in a directory structure, a group to which a user of the data segment belongs, a name of the data segment, an indication of whether structured or unstructured data are contained in the data segment, and an indication of a required data retention time.   
     
     
         6 . The method of  claim 5 , wherein:
 an observable is determined containing one or more variables of the set;   for each value of the observable a distribution of stored data segments across the relevance classes of the set is determined; and   the relevance class is assigned to the received data segment dependent on the distribution determined for a value of the observable that is identified for the received data segment.   
     
     
         7 . The method of  claim 6 , wherein:
 determining a distribution of stored data segments across the relevance classes for each value of the observable includes determining a conditional probability for each relevance class of the set given the value of the observable; and   
       the relevance class is assigned to the received data segment dependent on the conditional probabilities for the value of the observable identified in the received data segment. 
     
     
         8 . The method of  claim 7 , wherein the relevance class assigned to the received data segment is the relevance class out of the set with the highest conditional probability given the value of the observable identified. 
     
     
         9 . The method of  claim 6 , wherein the observable is adapted over time into an adapted observable. 
     
     
         10 . The method of  claim 9 , wherein:
 receiving the data segment includes receiving the data segment from the storage unit; and   determining the storage tier and a protection level includes re-determining a storage tier for moving the stored data segment to and re-determining a protection level for storing the stored data segment at dependent on the adapted observables.   
     
     
         11 . The method of  claim 6 , further comprising:
 defining a set of relevant topics;   assigning a topic of the set to each data segment received;   for each topic and each observable value determining a joint probability for a data segment containing such topic and observable value; and   determining or adapting the observable according to the determined joint probabilities.   
     
     
         12 . The method of  claim 11 , wherein the set of relevant topics is redefined over time thereby generating adapted observables.