Content addressable information encapsulation, representation and transfer

Abstract

Representing a number of assets on an originating computer begins with selecting the assets to be represented. Cryptographic hash asset identifiers are generated; each of the asset identifiers is computed using the contents of a particular asset. The asset identifier is a content-based or content-addressable asset name for the asset and is location independent. An asset list is generated that includes the asset identifiers computed from the assets. A cryptographic hash asset list identifier is generated that is computed from the asset list. The asset list identifier is stored for later retrieval. The assets selected are also stored for safekeeping either locally or on a computer network. In the event of loss of the files from the originating computer, the asset list identifier is retrieved. Using the asset list identifier, the original asset list is found and retrieved from its safe location. The asset identifiers from the retrieved asset list are used to find and retrieve the individual assets from their backup locations. The assets are verified by recomputing the cryptographic hash asset identifier for each asset retrieved and comparing it to the asset identifier from the asset list. The MD5 algorithm is used for the cryptographic hash function. Assets are retrieved using a multicast protocol. A series of importer programs searches for assets to retrieve in progressively more remote locations. Assets are retrieved whole or in segments.

1 . A method for use in a computer system comprising at least first and second computers, wherein the first computer provides content addressable storage, the method comprising an act of: 
 (A) transmitting, from the second computer to the first computer, a request to access a first portion of a unit of data stored by the first computer, the request identifying the unit of data via an identifier that is based, at least in part, on the content of the unit of data, the first portion of the unit of data comprising less than the entire unit of data.    
   
   
       2 . The method of  claim 1 , wherein the unit of data comprises at least one digital asset.  
   
   
       3 . The method of  claim 1 , wherein the act of transmitting comprises an act of transmitting a request that identifies the unit of data via an identifier that was generated by applying a cryptographic hash function to at least a portion of the content of the unit of data.  
   
   
       4 . The method of  claim 1 , further comprising an act of: 
 (B) receiving a second portion of the unit of data at the second computer.    
   
   
       5 . The method of  claim 4 , wherein the first portion of the unit of data comprises one or more individual segments of the unit of data that collectively comprise less than the entire unit of data so that the act (A) comprises an act of transmitting a request to access the one or more individual segments of the unit of data; and 
 wherein the second portion equals the first portion so that the act (B) comprises an act of receiving the one or more individual segments of the unit of data.    
   
   
       6 . The method of  claim 5 , wherein the individual segments comprise specific entries for a database or a code patch for a software application.  
   
   
       7 . The method of  claim 4 , wherein the first portion of the unit of data is the same as the second portion of the unit of data.  
   
   
       8 . The method of  claim 4 , wherein the second portion of the unit of data comprises less than the entire unit of data.  
   
   
       9 . The method of  claim 1 , wherein the first computer is a silo.  
   
   
       10 . The method of  claim 1 , wherein the first computer is a file server.  
   
   
       11 . The method of  claim 1 , wherein the first computer is a storage system.  
   
   
       12 . The method of  claim 1 , wherein the computer system comprises a plurality of computers in addition to the first and second computers and wherein the plurality of computers are interconnected by at least one network, and wherein each of the plurality of computers manages storage of one or more units of data.  
   
   
       13 . The method of  claim 1 , wherein the first and second computers are peer computers coupled by at least one network.  
   
   
       14 . The method of  claim 1 , wherein the unit of data is stored on the first computer.  
   
   
       15 . The method of  claim 1 , wherein the unit of data is stored by the first computer on a storage device managed by the first computer.  
   
   
       16 . At least one computer readable medium encoded with instructions that, when executed on a computer system, perform a method, the computer system comprising at least first and second computers, wherein the first computer provides content addressable storage, the method comprising an act of: 
 (A) transmitting, from the second computer to the first computer, a request to access a first portion of a unit of data stored by the first computer, the request identifying the unit of data via an identifier that is based, at least in part, on the content of the unit of data, the first portion of the unit of data comprising less than the entire unit of data.    
   
   
       17 . The at least one computer readable medium of  claim 16 , wherein the method further comprises an act of: 
 (B) receiving a second portion of the unit of data at the second computer.    
   
   
       18 . The at least one computer readable medium of  claim 17 , wherein the first portion of the unit of data comprises one or more individual segments of the unit of data that collectively comprise less than the entire unit of data so that the act (A) comprises an act of transmitting a request to access the one or more individual segments of the unit of data; and 
 wherein the second portion equals the first portion so that the act (B) comprises an act of receiving the one or more individual segments of the unit of data.    
   
   
       19 . The at least one computer readable medium of  claim 17 , wherein the first portion of the unit of data is the same as the second portion of the unit of data.  
   
   
       20 . The at least one computer readable medium of  claim 17 , wherein the second portion of the unit of data comprises less than the entire unit of data.  
   
   
       21 . A second computer for use in a computer system comprising at least a first computer and the second computer, wherein the first computer provides content addressable storage, the second computer comprising: 
 an output for transmitting access requests; and    at least one controller, coupled to the output, that transmits, from the second computer to the first computer, a request to access a first portion of a unit of data stored by the first computer, the request identifying the unit of data via an identifier that is based, at least in part, on the content of the unit of data, the first portion of the unit of data comprising less than the entire unit of data.    
   
   
       22 . The second computer of  claim 21 , wherein the at least one controller receives a second portion of the unit of data at the second computer.  
   
   
       23 . The second computer of  claim 22 , wherein the first portion of the unit of data comprises one or more individual segments of the unit of data that collectively comprise less than the entire unit of data so that the at least one controller transmits a request to access the one or more individual segments of the unit of data; and 
 wherein the second portion equals the first portion so that the at least one controller receives the one or more individual segments of the unit of data.    
   
   
       24 . The second computer of  claim 22 , wherein the first portion of the unit of data is the same as the second portion of the unit of data.  
   
   
       25 . The second computer of  claim 22 , wherein the second portion of the unit of data comprises less than the entire unit of data.