Architecture for supporting sparse volumes

Abstract

An architecture, including a file-level protocol, for supporting sparse volumes on a storage system is provided. The file-level protocol provides coherency checking for use in retrieving data stored on a backing store remote from a storage system.

1 . A storage system, comprising:
 a storage operating system executed by a processor, the storage operating system configured to generate a sparse volume, wherein the sparse volume comprises a structure marked with a value to identify that data of the sparse volume is not stored locally on a first storage system serving the sparse volume; and   a protocol module of the storage operating system configured to implement a protocol for remote retrieval of the data from a second storage system in response to a determination that the structure of the sparse volume has the value.   
   
   
       2 . The storage system of  claim 1  further comprising a function configured to load a block of the storage operating system. 
   
   
       3 . The storage system of  claim 1  wherein the protocol utilizes a transport control protocol/internet protocol for a transport layer. 
   
   
       4 . The storage system of  claim 1  wherein the protocol comprises a read request. 
   
   
       5 . The storage system of  claim 4  wherein the read request comprises a file handle field, a file block number field, and a number of blocks to be read field. 
   
   
       6 . The storage system of  claim 1  wherein the protocol comprises an authentication request. 
   
   
       7 . The storage system of  claim 6  wherein the authentication request comprises an application field, a type field, and a data field. 
   
   
       8 . The storage system of  claim 1  wherein the protocol comprises an authentication response. 
   
   
       9 . The storage system of  claim 8  wherein the authentication response comprises status field, and a data field. 
   
   
       10 . The storage system of  claim 1  wherein the protocol comprises a request to lock a persistent consistency point image (PCPI). 
   
   
       11 . The storage system of  claim 10  wherein the request comprises a file system identifier field, and a PCPI name field. 
   
   
       12 . The storage system of  claim 1  wherein the protocol comprises an initialize request. 
   
   
       13 . The storage system of  claim 12  wherein the initialize request comprises a protocol version field, an application field, and a byte order field. 
   
   
       14 . The storage system of  claim 1  wherein the protocol comprises an initialize response. 
   
   
       15 . The storage system of  claim 14  wherein the initialize response comprises a file system version field, and a byte order field. 
   
   
       16 . The storage system of  claim 1  wherein the second storage system comprises a backing store. 
   
   
       17 . The storage system of  claim 1  wherein the protocol comprises a set of operations that return attributes of a data container prior to and following set of operations. 
   
   
       18 . The system of clam  1  wherein the storage operating system is further configured to assign pointer values to indirect blocks of data retrieved from the backing store and stored locally. 
   
   
       19 . The system of  claim 1  wherein the protocol module is further configured to provide information to permit caching of data modified on an origin server. 
   
   
       20 . The system of  claim 1  wherein the protocol module is further configured to couple an open protocol to the protocol module. 
   
   
       21 . A method for operating a storage system, comprising:
 generating a sparse volume by a processor executing a storage operating system of a first storage system, wherein the sparse volume comprises a structure marked with a value to identify that data of the sparse volume is not stored locally on a first storage system serving the sparse volume; and   determining that the structure of the sparse volume has the value, and in response, implementing a protocol for remote retrieval of the data from a second storage system.   
   
   
       22 . The method of  claim 21  wherein the protocol utilizes a transport control protocol/internet protocol for a transport layer. 
   
   
       23 . The method of  claim 21  wherein the protocol comprises a read request. 
   
   
       24 . The method of  claim 23  wherein the read request comprises a file handle field, a file block number field, and a number of blocks to be read field. 
   
   
       25 . The method of  claim 21  wherein the second storage system comprises a backing store. 
   
   
       26 . The method of  claim 21  further comprising returning attributes of a data container prior to and following set of operations. 
   
   
       27 . The method of  claim 21  further comprising assigning pointer values to indirect blocks of data retrieved from the second storage system and stored locally on the first storage system. 
   
   
       28 . The method of  claim 21  further comprising providing information to permit caching of data modified on an origin server. 
   
   
       29 . The method of  claim 21  further comprising sending a lock PCPI command to the first storage system. 
   
   
       30 . A computer readable storage medium storing executable program instructions executed by a processor, comprising:
 program instructions that generate, by a processor executing a storage operating system of a first storage system, a sparse volume, wherein the sparse volume comprises a space reserved data container;   program instructions that mark a structure of the sparse volume with a value to identify that data of the sparse volume is not stored locally on the first storage system serving the sparse volume, wherein the data is stored locally on a second storage system; and   program instructions that determine that the structure of the sparse volume has the ii value, and in response, program instructions that implement a protocol for remote retrieval of the data from the second storage system.   
   
   
       31 . A method for operating a computer data storage system, comprising:
 storing first data locally and storing second data on a remote storage system;   placing an absent data pointer in a tree of pointers used to find requested data; and   retrieving the requested data from the remote storage system in response to finding the absent data pointer while searching the tree of pointers for the requested data.   
   
   
       32 . The method as in  claim 31 , further comprising:
 invoking a remote protocol module in response to detecting the absent data pointer, the remote protocol module to retrieve the requested data from the remote storage system.   
   
   
       33 . A computer data storage system apparatus, comprising:
 first data stored locally and second data stored on a remote storage system;   an absent data block pointer placed in a tree of pointers used to find a requested data block; and   s a remote protocol module configured to retrieve the requested data block from the remote storage system in response to finding the absent data block pointer while searching the tree of pointers for the requested data block.