Dynamic management of expandable cache storage for multiple network shares configured in a file server

Abstract

Expandable cache management dynamically manages cache storage for multiple network shares configured in a file server. Once a file is written to a directory or folder on a specially designated network share, such as one that is configured for “infinite backup,” an intermediary pre-backup copy of the file is created in an expandable cache in the file server that hosts the network share. On write operations, cache storage space can be dynamically expanded or freed up by pruning previously backed up data. This advantageously creates flexible storage caches in the file server for each network share, each cache managed independently of other like caches for other network shares on the same file server. On read operations, intermediary file storage in the expandable cache gives client computing devices speedy access to data targeted for backup, which is generally quicker than restoring files from backed up secondary copies.

What is claimed is: 
     
         1 . A method for managing storage for network shares configured in a file server, the method comprising:
 by the file server, receiving a write request comprising a first portion of a first file and designating a first network share configured in the file server as a storage destination for the write request;   by a cache manager that executes on the file server, identifying one or more storage volumes configured in the file server that comprise a respective share-specific folder that stores data for the first network share and only for the first network share;   if the cache manager determines that a first storage volume among the one or more storage volumes comprises sufficient storage space to store the first portion of the first file included in the write request,
 by the cache manager, storing the first portion of the first file to a respective share-specific folder in the first storage volume; 
   if the cache manager determines that the first storage volume lacks sufficient storage space for the first portion of the first file included in the write request,
 by the cache manager, storing the first portion of the first file to a respective share-specific folder in a second storage volume among the one or more storage volumes that comprises sufficient storage space for the first portion of the first file, regardless of whether other portions of the first file are stored in the second storage volume; and 
   if the cache manager determines that none of the one or more storage volumes comprises sufficient storage space for the first portion of the first file included in the write request, expanding the amount of storage available for the first network share on the file server by:
 (i) identifying by the cache manager a third storage volume configured in the file server, wherein the third storage volume comprises sufficient storage space for the first portion of the first file, 
 (ii) configuring by the cache manager in the third storage volume a respective share-specific folder for storing data for the first network share and only for the first network share, and 
 (iii) storing by the cache manager the first portion of the first file to the respective share-specific folder configured in the third storage volume. 
   
     
     
         2 . The method of  claim 1  further comprising:
 if the cache manager determines that none of the one or more storage volumes comprise sufficient storage space for the first portion of the first file included in the write request and no additional storage volumes are available in the file server for expanding the amount of storage available for the first network share,
 (A) by the cache manager, pruning data from at least one storage volume among the one or more storage volumes, wherein only data that has been previously backed up from the file server into secondary copies can be pruned, and 
 (B) by the cache manager, storing the first portion of the first file to a respective share-specific folder in the at least one volume that comprises sufficient storage space for the first portion of the first file after the pruning. 
 
 
     
     
         3 . The method of  claim 1 , wherein the first file is divided into a plurality of portions including the first portion; and
 wherein any given portion of the first file is stored to a respective share-specific folder configured on one of the one or more storage volumes, independently of whether another portion of the first file is also stored to the same respective share-specific folder on the same one of the one or more storage volumes.   
     
     
         4 . The method of  claim 1  wherein another write request comprises a second portion of the first file; and further comprising:
 for storing the second portion of the first file, identifying by the cache manager a storage volume among the one or more storage volumes that comprises sufficient storage space for the second portion of the first file regardless of whether the first portion of the first file is stored in the same storage volume. 
 
     
     
         5 . The method of  claim 1 , wherein the first network share is one of a plurality of network shares configured in the file server, and wherein the cache manager is associated with the first network share, and wherein storage in each of the plurality of network shares is managed by a respective cache manager associated with the respective network share. 
     
     
         6 . The method of  claim 1  further comprising:
 transmitting, by a protocol handler at the file server, the write request to a module that executes on the file server; 
 dividing, by the module, the first file into a plurality of portions including the first portion; and 
 transmitting, by the module, each portion of the plurality of portions to the cache manager, which is associated with the first network share. 
 
     
     
         7 . The method of  claim 1  wherein the cache manager retains information about which portion of the first file, including the first portion, is stored in which storage volume of the one or more storage volumes that comprise share-specific folders for storing data for the first network share and only for the first network share. 
     
     
         8 . The method of  claim 1  further comprising:
 on passing an administrative timeout interval, creating an entry for the first file in a backup queue that is associated with the first network share, wherein files entered in the backup queue are to be backed up into secondary copies stored in a secondary storage device distinct from the file server. 
 
     
     
         9 . A method for managing storage for network shares configured in a file server, the method comprising:
 by the file server, receiving a write request comprising a first portion of a first file and designating a first network share configured in the file server as a storage destination for the write request;   by a cache manager that executes on the file server, identifying one or more storage volumes configured in the file server that comprise a respective share-specific folder that stores data for the first network share and only for the first network share;   if the cache manager determines that a first storage volume among the one or more storage volumes comprises sufficient storage space to store the first portion of the first file included in the write request,   by the cache manager, storing the first portion of the first file to a respective share-specific folder in the first storage volume;   if the cache manager determines that the first storage volume lacks sufficient storage space for the first portion of the first file included in the write request,
 by the cache manager, storing the first portion of the first file to a respective share-specific folder in a second storage volume among the one or more storage volumes that comprises sufficient storage space for the first portion of the first file, regardless of whether other portions of the first file are stored in the second storage volume; and 
   if the cache manager determines that none of the one or more storage volumes comprise sufficient storage space for the first portion of the first file included in the write request and no additional storage volumes are available in the file server for expanding the amount of storage available for the first network share,
 (A) by the cache manager, pruning data from at least one storage volume among the one or more storage volumes, wherein only data that has been previously backed up from the file server into secondary copies can be pruned, and 
 (B) by the cache manager, storing the first portion of the first file to a respective share-specific folder in the at least one volume that comprises sufficient storage space for the first portion of the first file after the pruning. 
   
     
     
         10 . The method of  claim 9  further comprising:
 if the cache manager determines that none of the one or more storage volumes comprises sufficient storage space for the first portion of the first file included in the write request, causing the amount of storage available for the first network share on the file server to expand by:
 (i) identifying by the cache manager a third storage volume configured in the file server, wherein the third storage volume comprises sufficient storage space for the first portion of the first file, 
 (ii) configuring by the cache manager in the third storage volume a respective share-specific folder for storing data for the first network share and only for the first network share, and 
 (iii) storing, by the cache manager, the first portion of the first file to the respective share-specific folder configured in the third storage volume. 
 
 
     
     
         11 . The method of  claim 9 , wherein the pruning is based on an age of the data that has been previously backed up. 
     
     
         12 . The method of  claim 9 , wherein the pruning is based on a size of a file that has been previously backed up. 
     
     
         13 . The method of  claim 9 , wherein an amount of data that is pruned is sufficient to reach an administrable threshold. 
     
     
         14 . The method of  claim 9 , wherein criteria for pruning the data that has been previously backed up are administrable. 
     
     
         15 . The method of  claim 9 , wherein the first file is divided into a plurality of portions including the first portion, and
 wherein any given portion of the first file is stored to a respective share-specific folder configured on one of the one or more storage volumes independently of whether another portion of the first file is also stored to the same respective share-specific folder on the same one of the one or more storage volumes.   
     
     
         16 . The method of  claim 9 , wherein whether sufficient storage space is available to store the first portion of the first file is determined by the cache manager based on one or more administrable thresholds. 
     
     
         17 . The method of  claim 9 , wherein another write request comprises a second portion of the first file; and further comprising:
 for storing the second portion of the first file, identifying by the cache manager a storage volume among the one or more storage volumes that comprises sufficient storage space for the second portion of the first file regardless of whether the first portion of the first file is stored in the same storage volume.   
     
     
         18 . The method of  claim 9  further comprising:
 creating an entry for the first file in a backup queue at the file server, wherein a backup interface module that executes on the file server is configured to receive from a storage manager one or more instructions to generate at least one secondary copy of files identified by entries in the backup queue; 
 generating by the backup interface module, in conjunction with a media agent, a secondary copy of the first file based on the one or more instructions received from the storage manager; and 
 by the media agent, storing the secondary copy of the first file to a secondary storage device and reporting metadata about the secondary copy to at least one of: an index server in communication with the file server, and the storage manager. 
 
     
     
         19 . The method of  claim 18 , wherein the entry for the first file is created in the backup queue after passing an administrative timeout interval. 
     
     
         20 . The method of  claim 9 , wherein the cache manager retains information about which portion of the first file, including the first portion, is stored in which storage volume of the one or more storage volumes that comprise share-specific folders for storing data for the first network share and only for the first network share.