Checkpoints for a file system

Abstract

Aspects of the subject matter described herein relate to checkpoints for a file system. In aspects, updates to the file system are organized into checkpoint buckets. When a checkpoint is desired, subsequent updates are directed to another checkpoint bucket. After global tables have been updated for updates in the current checkpoint bucket, a logical copy of the global tables is created. This logical copy is stored as part of the checkpoint data. To assist in recovery, a checkpoint manager may wait until all updates of the current checkpoint bucket have been written to storage before writing final checkpoint data to storage. This final checkpoint data may refer to the logical copy of the global tables and include a validation code to verify that the checkpoint data is correct.

What is claimed is: 
     
         1 . A method performed on at least one computing device that includes at least one processing unit and a memory, the method comprising:
 generating, by the at least one computing device, a write plan for writing, to a second location, an update to a file system, where the update is to an object stored at a first location, where the object is of the file system, where the update is associated with a checkpoint, and where the second location is different than the first location; and   writing, by the at least one computing device in connection with the update being written to the second location in accordance with the generated write plan, information about the checkpoint to the second location, the written information comprising the generated write plan and a checkpoint record.   
     
     
         2 . The method of  claim 1  where the checkpoint information indicates at least one update to the file system. 
     
     
         3 . The method of  claim 1  where the checkpoint information includes a validation code sufficient for determining that the written checkpoint information was correctly written. 
     
     
         4 . The method of  claim 1  where the write plan indicates a location for at least one update to the file system. 
     
     
         5 . The method of  claim 1  where the checkpoint information indicates a storage location of the object. 
     
     
         6 . The method of  claim 1  where the checkpoint information includes space allocation information. 
     
     
         7 . The method of claim where the writing is subsequent the update to the object being written to the first location. 
     
     
         8 . A system including at least one computing device and at least one program module that are together configured for performing actions, where the at least one computing device includes at least one processing unit and a memory, the actions comprising:
 generating, by the at least one computing device, a write plan for writing, to a second location, an update to a file system, where the update is to an object stored at a first location, where the object is of the file system, where the update is associated with a checkpoint, and where the second location is different than the first location; and   writing, by the at least one computing device in connection with the update being written to the second location in accordance with the generated write plan, information about the checkpoint to the second location, the written information comprising the generated write plan and a checkpoint record.   
     
     
         9 . The system of  claim 8  where the checkpoint information indicates at least one update to the file system. 
     
     
         10 . The system of  claim 8  where the checkpoint information includes a validation code sufficient for determining that the written checkpoint information was correctly written. 
     
     
         11 . The system of  claim 8  where the write plan indicates a location for at least one update to the file system. 
     
     
         12 . The system of  claim 8  where the checkpoint information indicates a storage location of the object. 
     
     
         13 . The system of  claim 8  where the checkpoint information includes space allocation information. 
     
     
         14 . The system of  claim 8  where the writing is subsequent to the update to the object being written to the first location. 
     
     
         15 . At least one computer storage media storing computer-executable instructions that, when executed by at least one computing device that includes at least one processing unit and a memory, cause the at least one computing device to perform actions comprising:
 generating, by the at least one computing device, a write plan for writing, to a second location, an update to a file system, where the update is to an object stored at a first location, where the object is of the file system, where the update is associated with a checkpoint, and where the second location is different than the first location; and   writing, by the at least one computing device in connection with the update being written to the second location in accordance with the generated write plan, information about the checkpoint to the second location, the written information comprising the generated write plan and a checkpoint record.   
     
     
         16 . The at least one computer storage media of  claim 15  where the checkpoint information indicates at least one update to the file system. 
     
     
         17 . The at least one computer storage media of  claim 15  where the checkpoint information includes a validation code sufficient for determining that the written checkpoint information was correctly written. 
     
     
         18 . The at least one computer storage media of  claim 15  where the write plan indicates a location for at least one update to the file system. 
     
     
         19 . The at least one computer storage media of  claim 15  where the checkpoint information indicates a storage location of the object, or where the checkpoint information includes space allocation information. 
     
     
         20 . The at least one computer storage media of  claim 15  where the writinq is subsequent to the update to the object being written to the first location.