File system quiescing driver

Abstract

A technique is disclosed for quiescing a file system. The technique includes holding a change request, flushing the file system, and releasing the change request. Flushing may include sending a flush request, determining whether a cache associated with the file system is flushed, and in the event that the cache is not flushed, resending the flush request and determining whether the cache is flushed.

What is claimed is: 
     
         1 . A method of quiescing a file system, comprising:
 sending a flush request;   determining with a processor whether a cache associated with the file system is flushed;   in an event that the cache is not flushed, resending the flush request; and   in an event that the cache is flushed, taking a snapshot associated with the file system.   
     
     
         2 . The method of  claim 1 , further comprising:
 intercepting a change request to prevent the change request from reaching the file system prior to sending the flush request.   
     
     
         3 . The method of  claim 2 , further comprising:
 releasing the change request after taking the snapshot.   
     
     
         4 . The method of  claim 2 , wherein the change request is a write request. 
     
     
         5 . The method of  claim 2 , wherein the change request is a user mode change request. 
     
     
         6 . The method of  claim 5 , wherein the user mode change request is requested by an application. 
     
     
         7 . The method of  claim 2 , wherein a file system quiescing driver holds the change request. 
     
     
         8 . The method of  claim 2 , wherein a filter driver holds the change request. 
     
     
         9 . The method of  claim 2 , wherein a sync driver holds the change request. 
     
     
         10 . The method of  claim 1 , wherein the file system interacts with a layered device I/O architecture. 
     
     
         11 . The method of  claim 1 , wherein an object associated with a file system quiescing driver is inserted in a device stack. 
     
     
         12 . The method of  claim 1 , wherein an object associated with a file system quiescing driver is inserted at the top of a device stack. 
     
     
         13 . The method of  claim 1 , further including backing up the file system. 
     
     
         14 . The method of  claim 1 , further including creating a sync driver device object. 
     
     
         15 . The method of  claim 1 , further including holding a kernel mode change request. 
     
     
         16 . The method of  claim 1 , wherein the file system is a WINDOWS based file system. 
     
     
         17 . The method of  claim 1 , wherein the file system is a WINDOWS NT, WINDOWS 2000, or WINDOWS 2003 file system. 
     
     
         18 . A system for quiescing a file system, comprising:
 a processor; and   a memory coupled with the processor, wherein the memory is configured to provide the processor with instructions which when executed cause the processor to:
 send a flush request; 
 determine whether a cache associated with the file system is flushed; 
 in an event that the cache is not flushed, resend the flush request; and 
 in an event that the cache is flushed, take a snapshot associated with the file system. 
   
     
     
         19 . The system of  claim 18 , wherein the memory is further configured to provide the processor with instructions which when executed cause the processor to:
 intercept a change request to prevent the change request from reaching the file system prior to sending the flush request.   
     
     
         20 . The system of  claim 19 , wherein the memory is further configured to provide the processor with instructions which when executed cause the processor to:
 release the change request after taking the snapshot.   
     
     
         21 . The system of  claim 19 , wherein the change request is a write request. 
     
     
         22 . The system of  claim 19 , wherein the change request is a user mode change request. 
     
     
         23 . The system of  claim 22 , wherein the user mode change request is requested by an application. 
     
     
         24 . The system of  claim 19 , wherein a file system quiescing driver holds the change request. 
     
     
         25 . The system of  claim 19 , wherein a filter driver holds the change request. 
     
     
         26 . The system of  claim 19 , wherein a sync driver holds the change request. 
     
     
         27 . The system of  claim 19 , wherein the file system interacts with a layered device I/O architecture. 
     
     
         28 . The system of  claim 18 , wherein an object associated with a file system quiescing driver is inserted in a device stack. 
     
     
         29 . The system of  claim 18 , wherein an object associated with a file system quiescing driver is inserted at the top of a device stack. 
     
     
         30 . The system of  claim 18 , wherein the memory is further configured to provide the processor with instructions which when executed cause the processor to back up the file system. 
     
     
         31 . The system of  claim 18 , wherein the memory is further configured to provide the processor with instructions which when executed cause the processor to create a sync driver device object. 
     
     
         32 . The system of  claim 18 , wherein the memory is further configured to provide the processor with instructions which when executed cause the processor to hold a kernel mode change request. 
     
     
         33 . The system of  claim 18 , wherein the file system is a WINDOWS based file system. 
     
     
         34 . The system of  claim 18 , wherein the file system is a WINDOWS NT, WINDOWS 2000, or WINDOWS 2003 file system. 
     
     
         35 . A computer program product for quiescing a file system, the computer program product being embodied in a tangible computer readable storage medium and comprising computer instructions for:
 sending a flush request;   determining with a processor whether a cache associated with the file system is flushed;   in an event that the cache is not flushed, resending the flush request; and   in an event that the cache is flushed, taking a snapshot associated with the file system.