Method and system for accessing auxiliary data in power-efficient high-capacity scalable storage

Abstract

A method for preparing data units for access in a data storage system is disclosed. The data storage system includes multiple storage devices having data units. All the storage devices of the data storage system are not powered on at the same time. The method includes preparing and storing the auxiliary data. The auxiliary data is prepared for a data unit on a storage device that will be powered off during an access request of the data unit. The auxiliary data is stored on the storage devices so that the auxiliary data is likely to be available on a powered-on storage device when the data unit is the subject of an access request.

1 . A method for preparing data units for access in a data storage system, the data storage system comprising a plurality of storage devices having data units, wherein not all of the storage devices are powered on at the same time, the method comprising: 
 preparing auxiliary data for a data unit on a storage device that will be powered off during an access request of the data unit; and    storing the auxiliary data on a plurality of the storage devices so that the auxiliary data is always available on a powered-on storage device when the data unit is the subject of an access request.    
   
   
       2 . The method of  claim 1 , wherein the auxiliary data is stored on all of the storage devices.  
   
   
       3 . The method of  claim 1 , further comprising: 
 using an auxiliary data area on a storage device to store the auxiliary data; and    updating the auxiliary data.    
   
   
       4 . The method of  claim 3 , further comprising: 
 using a change log and a generation identification number to update the auxiliary data.    
   
   
       5 . The method of  claim 4 , wherein the generation identification number is incremented each time the auxiliary data is updated.  
   
   
       6 . The method of  claim 4 , wherein the auxiliary data is updated on the auxiliary data area when the generation identity number is not latest.  
   
   
       7 . The method of  claim 4 , wherein the change log includes updates corresponding to each increment of the generation identification number.  
   
   
       8 . The method of  claim 3 , wherein the auxiliary data is updated from one set of storage devices to a next set of storage devices when the next set of storage devices is being powered on upon the access request.  
   
   
       9 . The method of  claim 3 , wherein updating the auxiliary data comprises: 
 modifying the auxiliary data on all of powered-on storage devices of the data storage system when the access request is a write operation.    
   
   
       10 . The method of  claim 1 , wherein the auxiliary data is read from one of powered-on storage devices of the data storage system when the access request is a read operation.  
   
   
       11 . The method of  claim 1 , wherein the access request is received from a host.  
   
   
       12 . The method of  claim 1 , wherein preparing the auxiliary data for the data unit comprises: 
 configuring the data storage system during a boot cycle of the data storage system; and    synchronizing the auxiliary data in all data units of the data storage system.    
   
   
       13 . The method of  claim 12 , wherein configuring the data storage system comprises: 
 assigning an auxiliary data area on each storage device of the data storage system to a set of logical blocks of one or more data units of the data storage system; and    collecting the auxiliary data from the auxiliary data area to the set of logical blocks of the one or more data units.    
   
   
       14 . The method of  claim 12 , further comprising: 
 reconfiguring auxiliary data areas on all of the storage devices.    
   
   
       15 . The method of  claim 14 , wherein reconfiguring the auxiliary data areas comprises: 
 unpinning auxiliary data from the auxiliary data areas that are no longer in the configuration;    assigning new auxiliary data areas to the set of logical blocks of the one or more data units; and    collecting data from the set of logical blocks of the one or more data units to the new auxiliary data areas.    
   
   
       16 . The method of  claim 15 , wherein reconfiguring the auxiliary data areas further comprises: 
 modifying the set of logical blocks by using a vendor unique command that is received through one of an out-of-band and an in-band interface.    
   
   
       17 . The method of  claim 16 , further comprising: 
 synchronizing data in the auxiliary data areas.    
   
   
       18 . The method of  claim 1 , further comprising: 
 maintaining the auxiliary data on a set of storage devices of the plurality of storage devices in a background mode when a storage management unit of the data storage system is idle for a predetermined time.    
   
   
       19 . The method of  claim 18 , wherein maintaining the auxiliary data comprises: 
 powering on the set of storage devices in the background mode.    
   
   
       20 . The method of  claim 19 , wherein powering on the set of storage devices further comprises: 
 periodically swapping powered-on storage devices in the set of storage device with storage devices that are powered-off.    
   
   
       21 .- 32 . (canceled)