Re-trim of free space within vhdx

Abstract

An invention is disclosed for maintaining out-of-band metadata for data. In embodiments of the invention, an upper layer of a storage stack determines that the metadata of a lower layer of that storage stack may have become out of sync. In response, the upper layer may issue a series of commands to the lower layer based on the metadata. In other embodiments of the invention, an offload-copy operation on data may also transfer out-of-band metadata so that it is applied to the data at the destination.

What is claimed: 
     
         1 . A method for implementing an offload copy that maintains out-of-band metadata, comprising:
 receiving an indication to copy data from a source to a destination;   determining out-of-band metadata that corresponds to the data; and   copying the out-of-band metadata to a location where out-of-band metadata is stored for the destination.   
     
     
         2 . The method of  claim 1 , further comprising:
 determining that the out-of-band metadata is to be copied to the destination based on a type of the out-of-band metadata.   
     
     
         3 . The method of  claim 2 , wherein determining that the out-of-band metadata is to be copied to the destination based on a type of the out-of-band metadata comprises:
 determining that the out-of-band metadata comprises information for TRIM commands.   
     
     
         4 . The method of  claim 2 , wherein determining that the out-of-band metadata is to be copied to the destination based on a type of the out-of-band metadata comprises:
 determining that the out-of-band metadata comprises information for unmap commands.   
     
     
         5 . The method of  claim 2 , wherein determining that the out-of-band metadata is to be copied to the destination based on a type of the out-of-band metadata comprises:
 determining that the out-of-band metadata comprises information for data de-duplication hashes.   
     
     
         6 . The method of  claim 2 , further comprising:
 receiving an indication to copy second data from a second source to a second destination; and   determining not to copy second out-of-band metadata of the second data with the second data based on a type of the second out-of-band metadata, and a type of the second destination.   
     
     
         7 . The method of  claim 6 , wherein determining not to copy the second out-of-band metadata of the second data with the second data based on a type of the second out-of-band metadata, and a type of the second destination comprises:
 determining that the type of the second out-of-band metadata is a heat map, and that the type of the second destination is backup that will not be actively used.   
     
     
         8 . The method of  claim 1 , further comprising:
 determining that the out-of-band metadata is to be copied to the destination based on a type of the destination.   
     
     
         9 . The method of  claim 1 , further comprising:
 generating a token based on the data, the token comprising a cryptographically-secure string that identifies scoped, immutable data;   storing the token in a buffer;   retrieving the token from the buffer; and   writing the data as identified by the token to the destination.   
     
     
         10 . The method of  claim 1 , wherein copying the out-of-band metadata to the location where out-of-band metadata is stored for the destination comprises:
 updating destination metadata appropriately based on source metadata in a lower layer, wherein the indication to copy data is issued to an upper layer.   
     
     
         11 . The method of  claim 1 , wherein the source comprises a source storage stack, and the destination comprises a holding area associated with a token, or wherein the source comprises the token, and the destination comprises a destination storage stack. 
     
     
         12 . A computer-readable storage medium for implementing an offload copy that maintains out-of-band metadata, bearing computer-executable instructions that, when executed upon a computer, cause the computer to perform operations comprising:
 receiving, by a copy provider, an indication to copy data from a source to a destination, the source being a storage stack of a computer system, the storage stack comprising a layer that maintains out-of-band metadata;   determining out-of-band metadata that corresponds to the data; and   copying the out-of-band metadata to a location where out-of-band metadata is stored for the destination.   
     
     
         13 . The computer-readable storage medium of  claim 12 , further bearing computer-executable instructions that, when executed upon the computer, cause the computer to perform operations comprising:
 determining that the out-of-band metadata is to be copied to the destination based on a type of the out-of-band metadata.   
     
     
         14 . The computer-readable storage medium of  claim 13 , wherein determining that the out-of-band metadata is to be copied to the destination based on a type of the out-of-band metadata comprises:
 determining that the out-of-band metadata comprises information for TRIM commands.   
     
     
         15 . The computer-readable storage medium of  claim 13 , wherein determining that the out-of-band metadata is to be copied to the destination based on a type of the out-of-band metadata comprises:
 determining that the out-of-band metadata comprises information for unmap commands.   
     
     
         16 . The computer-readable storage medium of  claim 13 , wherein determining that the out-of-band metadata is to be copied to the destination based on a type of the out-of-band metadata comprises:
 determining that the out-of-band metadata comprises information for data de-duplication hashes.   
     
     
         17 . The computer-readable storage medium of  claim 13 , further bearing computer-executable instructions that, when executed upon the computer, cause the computer to perform operations comprising:
 receiving an indication to copy second data from a second source to a second destination; and   determining not to copy second out-of-band metadata of the second data with the second data based on a type of the second out-of-band metadata, or a type of the second destination.   
     
     
         18 . The computer-readable storage medium of  claim 17 , wherein determining not to copy the second out-of-band metadata of the second data with the second data based on a type of the second out-of-band metadata, and a type of the second destination comprises:
 determining that the type of the second out-of-band metadata is a heat map, and that the type of the second destination is backup that will not be actively used.   
     
     
         19 . The computer-readable storage medium of  claim 12 , further bearing computer-executable instructions that, when executed upon the computer, cause the computer to perform operations comprising:
 determining that the out-of-band metadata is to be copied to the destination based on a type of the destination.   
     
     
         20 . A system for implementing an offload copy that maintains out-of-band metadata, comprising:
 a processor; and   a memory communicatively coupled to the processor when the system is operational, the memory bearing processor-executable instructions that, when executed on the processor, cause the system to at least:
 receive an indication to copy data from a copy provider to a destination; 
 write, by the copy provider, the data to the destination; 
 determine out-of-band metadata that corresponds to the data; and 
 copy the out-of-band metadata to a location where out-of-band metadata is stored for the destination.