Storage apparatus and storage area arrangement method

Abstract

This storage apparatus for providing a dynamically expandable virtual volume to a host system to access the virtual volume comprises an allocation unit for configuring a group with a plurality of disks for providing a storage area to be allocated to the virtual volume, and allocating the storage area respectively from a plurality of the groups to the virtual volume; and a storage area arrangement unit for rearranging the storage area in each of the groups being used by the virtual volume to become optimal among each of the groups based on external operation.

What is claimed is: 
     
         1 . A storage apparatus comprising:
 a plurality of disk drives; and   a controller that is configured to:
 provide a plurality of RAID groups from the plurality of disk drives; 
 provide a plurality of virtual volumes by allocating a storage area from at least one of the plurality of the RAID groups; 
 manage configuration information which includes an identifier of a virtual volume, an identifier of the RAID group which allocates the storage area to the virtual volume and a size of the storage area; and 
 execute a rearranging process to respective virtual volume, the rearranging process being configured to:
 comparing the size of the storage area between the virtual volume and the RAID group; and 
 if a difference of the storage area is larger than a threshold partially based on the configuration information, at least one storage area of the RAID group is migrated to at least one other RAID group in order to make the difference smaller. 
 
   
     
     
         2 . The storage apparatus according to  claim 1 ,
 wherein the controller executes the rearranging process when a new disk drive is added to the storage apparatus.   
     
     
         3 . The storage apparatus according to  claim 1 , wherein the controller is further configured to rearrange a plurality of storage areas in the RAID groups used by a virtual volume to become equal among the plurality of RAID groups based on the configuration information. 
     
     
         4 . The storage apparatus according to  claim 1 , wherein the controller is further configured to rearrange a plurality of storage areas in the RAID groups accessed within a prescribed time to become equal among the plurality of RAID groups based on the configuration information. 
     
     
         5 . The storage apparatus according to  claim 1 , wherein the controller is further configured to rearrange a plurality of storage areas in the RAID groups not used by a virtual volume to become equal among the plurality of RAID groups based on the configuration information. 
     
     
         6 . The storage apparatus according to  claim 1 , wherein, when a new RAID group configured from low-performance disk drives that have a lower performance in comparison to the plurality of disk drives is added for allocating the plurality of storage areas to a virtual volume, the controller rearranges the plurality of storage areas with an old access time in the plurality of storage areas in the RAID group of low-performance disk drives based on the configuration information. 
     
     
         7 . The storage apparatus according to  claim 1 , further comprising a plurality of management units for managing a plurality of storage areas of the plurality of RAID groups configured from a plurality of external disk drives, wherein the controller rearranges the plurality of storage areas being used by a virtual volume and being managed by each of the management units to become optimal among each of the management units based on the configuration information. 
     
     
         8 . A method for rearranging data of a storage apparatus which comprises:
 a plurality of disk drives; and   a controller;   the method comprising the steps of:   providing a plurality of RAID groups from the plurality of disk drives;   providing a plurality of virtual volumes by allocating a storage area from at least one of the plurality of the RAID groups;   managing configuration information which includes an identifier of a virtual volume, an identifier of the RAID group which allocates the storage area to the virtual volume and a size of the storage area; and   executing a rearranging processes to respective virtual volume, the rearranging process being configured to:
 comparing the size of the storage area between the virtual volume and the RAID group; and 
 if a difference of the storage area is larger than a threshold partially based on the configuration information, at least one storage area of the RAID group is migrated to at least one other RAID group in order to make the difference smaller. 
   
     
     
         9 . The method for rearranging data according to  claim 8 ,
 wherein the rearranging process is executed when a new disk drive is added to the storage apparatus.   
     
     
         10 . The method according to  claim 8 , wherein a plurality of storage areas in the RAID groups used by a virtual volume is rearranged to become equal among the plurality of RAID groups based on the configuration information. 
     
     
         11 . The method according to  claim 8 , wherein a plurality of storage areas in the RAID groups accessed within a prescribed time is rearranged to become equal among the plurality of RAID groups based on the configuration information. 
     
     
         12 . The method according to  claim 8 , wherein a plurality of storage areas in the RAID groups not used by a virtual volume is rearranged to become equal among the plurality of RAID groups based on the configuration information. 
     
     
         13 . The method according to  claim 8 , wherein when a new RAID group configured from low-performance disk drives that have a lower performance in comparison to the plurality of disk drives is added for allocating a plurality of storage areas to a virtual volume, the plurality of storage areas with an old access time is rearranged in the storage areas in the RAID group of low-performance disk drives based on the configuration information. 
     
     
         14 . The method according to  claim 8 , wherein a plurality of storage areas being used by a virtual volume and being managed by a plurality of management units for managing the plurality of storage areas of the plurality of RAID groups configured from a plurality of external disk drives is rearranged to become optimal among each of the management units based on the configuration information. 
     
     
         15 . The storage apparatus according to  claim 1 , wherein the controller executes the rearranging process in response to a request from a host system. 
     
     
         16 . The method according to  claim 8 , wherein executing the rearranging process in response to a request from a host system.