Efficient Creation And Management Of Snapshots

Abstract

A method including, based on a request targeting a logical volume mapped to a logical grouping of data, splitting the logical grouping of data into two or more ranges including a first range and a second range, wherein lookups corresponding to one or more blocks targeted by the request are performed in the first range of the two or more ranges, and performing the request using the second range.

What is claimed is: 
     
         1 . A computer system comprising:
 one or more storage devices; and   a storage controller;   wherein the storage controller is configured to:   based on a request targeting a logical volume mapped to a logical grouping of data, split the logical grouping of data into two or more ranges including a first range and a second range, wherein lookups corresponding to one or more blocks targeted by the request are performed in a range of the two or more ranges; and   perform the request using the second range.   
     
     
         2 . The computer system of  claim 1 , wherein the one or more storage devices are solid state storage devices. 
     
     
         3 . The computer system of  claim 1 , wherein each of the one or more storage devices comprises a flash chip. 
     
     
         4 . The computer system of  claim 1 , wherein the computer system is a flash system. 
     
     
         5 . The computer system of  claim 1 , wherein an unmasked status indicates that a lookup should be performed in a first logical grouping of data that is mapped to the logical volume, and wherein a masked status indicates that a lookup should only be performed in a second logical grouping of data that underlies the first logical grouping of data. 
     
     
         6 . The computer system of  claim 1 , wherein the storage controller is configured to store an indication for lookups to be performed in the second range and not the first range. 
     
     
         7 . The computer system of  claim 1 , further comprising storing an indication that the first range is read-only, including changing a status of the first range from read-write to read only. 
     
     
         8 . A method, comprising:
 based on a request targeting a logical volume mapped to a logical grouping of data, splitting the logical grouping of data into two or more ranges including a first range and a second range, wherein lookups corresponding to one or more blocks targeted by the request are performed in a range of the two or more ranges; and   performing the request using the second range.   
     
     
         9 . The method of  claim 8 , wherein the method comprises a method of operation in a flash system. 
     
     
         10 . The method of  claim 8 , further comprising storing a volume to medium mapping table in one or more storage devices, wherein the one or more storage devices are solid state storage devices. 
     
     
         11 . The method of  claim 10 , wherein each of the one or more storage devices comprises a flash chip. 
     
     
         12 . The method of  claim 8 , wherein the first range of the logical grouping of data maps to another logical grouping, and the request is performed on the second range of the logical grouping of data. 
     
     
         13 . The method of  claim 8 , wherein an unmasked status indicates that a lookup should be performed in a first logical grouping of data that is mapped to the logical volume, and wherein a masked status indicates that a lookup should only be performed in a second logical grouping of data that underlies the first logical grouping of data. 
     
     
         14 . The method of  claim 8 , further comprising storing an indication for lookups to be performed in the second range and not the first range. 
     
     
         15 . The method of  claim 8 , further comprising storing an indication that the first range is read-only, including changing a status of the first range from read-write to read only. 
     
     
         16 . A non-transitory computer readable storage medium storing program instructions, wherein the program instructions are executable by a processor of a computer system to:
 in response to receiving a request identifying a volume and indicating a command to take a snapshot of the volume, wherein the volume is mapped to a first logical grouping of data:   based on a request targeting a logical volume mapped to a logical grouping of data, split the logical grouping of data into two or more ranges including a first range and a second range, wherein lookups corresponding to one or more blocks targeted by the request are performed in a range of the two or more ranges; and   perform the request using the second range.   
     
     
         17 . The non-transitory computer readable storage medium of  claim 16 , wherein the program instructions comprise a method of operation in a flash system. 
     
     
         18 . The non-transitory computer readable storage medium of  claim 16 , wherein an unmasked status indicates that a lookup should be performed in a first logical grouping of data that is mapped to the logical volume, and wherein a masked status indicates that a lookup should only be performed in a second logical grouping of data that underlies the first logical grouping of data. 
     
     
         19 . The non-transitory computer readable storage medium of  claim 16 , wherein the program instructions further cause the processor to store an indication for lookups to be performed in the second range and not the first range. 
     
     
         20 . The non-transitory computer readable storage medium of  claim 16 , wherein the program instructions further cause the processor to store an indication that the first range is read-only, including changing a status of the first range from read-write to read only.