Computing machine migration

Abstract

Systems and methods for migration between computing machines are disclosed. The source and target machines can be either physical or virtual; the source can also be a machine image. The target machine is connected to a snapshot or image of the source machine file system, and a redo-log file is created on the file system associated with the target machine. The target machine begins operation by reading data directly from the snapshot or image of the source machine file system. Thereafter, all writes are made to the redo-log file, and subsequent reads are made from the redo-log file if it contains data for the requested sector or from the snapshot or image if it does not. The source machine continues to be able to run separately and simultaneously after the target machine begins operation.

1 . A method for migrating a file system associated with a source computing machine to a virtual machine, the method comprising:
 connecting an image of the file system to the virtual machine;   beginning operation of the virtual machine by enabling the virtual machine to read data from the image before a complete copy of the file system is copied to a file system of the virtual machine; and   enabling the source computing machine to continue to run separately and simultaneously with the virtual machine after the virtual machine begins operation.   
     
     
         2 . The method of  claim 1 , further comprising creating a redo-log file on the file system of the virtual machine, wherein the virtual machine performs file-system writes to the redo-log file and performs file-system reads from the redo-log file if the redo-log file contains data for a requested sector or from the image if said redo-log file does not contain data for the requested sector. 
     
     
         3 . The method of  claim 2 , further comprising:
 enabling the virtual machine to make a change to the redo-log file; and   migrating the changed redo-log file of the virtual machine to the source computing machine.   
     
     
         4 . The method of  claim 3 , wherein migrating the changed redo-log file of the virtual machine to the source computing machine comprises cloning the change to the redo-log file back into the file system to replace the corresponding memory locations in the file system. 
     
     
         5 . The method of  claim 1 , wherein a background process is run to clone one or more portions of the file system to the virtual machine. 
     
     
         6 . The method of  claim 1 , wherein said source computing machine is a physical machine executing the virtual machine. 
     
     
         7 . The method of  claim 6 , wherein said image is a snapshot of the file system of the physical machine. 
     
     
         8 . The method of  claim 6 , wherein the image is obtained from a stored backup image of the file system of the physical machine. 
     
     
         9 . The method of  claim 1 , wherein reads from the image are cached by the virtual machine, and subsequent reads from cached sectors are read from the cache. 
     
     
         10 . A system for migrating a file system associated with a source computing machine to a virtual machine, the system comprising:
 a connection for connecting an image of the file system to the virtual machine; and   one or more processors programmed to:
 create a snapshot or image of the file system; 
 enable the virtual machine read data from the snapshot or the image before a complete copy of the file system is copied to a file system of the virtual machine; and 
 enabling the source computing machine to continue to run separately and simultaneously with the virtual machine after the virtual machine begins operation by reading the data from the snapshot or the image. 
   
     
     
         11 . The system of  claim 10 , further comprising a redo-log file on the file system of the virtual machine, and wherein the one or more processors are further programmed to manage file-system access such that the virtual machine performs file-system writes to the redo-log file and performs file system reads from the redo-log file if the redo-log file already contains data for a requested sector or from the snapshot or the image if the redo-log file does not contain data for the requested sector. 
     
     
         12 . The system of  claim 11 , wherein the one or more processors are further programmed to:
 enable the virtual machine to make a change to the redo-log file; and   migrate the changed redo-log file of the virtual machine back to the source computing machine.   
     
     
         13 . The system of  claim 10 , wherein the one or more processors are further programmed to run a background process to clone one or more portions of the file system to the virtual machine after the virtual machine begins operation. 
     
     
         14 . The system of  claim 10 , wherein the one or more processors are further programmed to cache reads by the virtual machine from the snapshot or the image and to read cached file-system sectors preferentially when present. 
     
     
         15 . The system of  claim 10 , wherein the file-system reads from the snapshot or the image are performed from one of the following: a cache of reads of the snapshot or the image; a clone of the snapshot or the image or a portion thereof; or the snapshot or the image, using the first of these alternatives that exists and contains data for the requested sector or sectors. 
     
     
         16 . One or more computer-readable media comprising computer executable instructions for migrating a file system associated with a source computing machine to a virtual machine, the computer executable instructions when executed by one or more processors, cause the one or more processors to:
 connect an image of the file system to the virtual machine;   begin operation of the virtual machine by enabling the virtual machine to read data from the image before a complete copy of the file system is copied to a file system of the virtual machine; and   enable the source computing machine to continue to run separately and simultaneously with the virtual machine after the virtual machine begins operation.   
     
     
         17 . The one or more computer-readable media of  claim 16 , wherein the computer executable instructions further cause the one or more processors to create a redo-log file on the file system of the virtual machine, wherein the virtual machine performs file-system writes to the redo-log file and performs file-system reads from the redo-log file if the redo-log file contains data for a requested sector or from the image if said redo-log file does not contain data for the requested sector. 
     
     
         18 . The one or more computer-readable media of  claim 16 , wherein the computer executable instructions further cause the one or more processors to:
 enable the virtual machine to make a change to the redo-log file; and   migrate the changed redo-log file of the virtual machine back to the source computing machine.   
     
     
         19 . The one or more computer-readable media of  claim 16 , wherein the computer executable instructions further cause the one or more processors to run a background process to clone one or more portions of the file system to the virtual machine after the virtual machine begins operation. 
     
     
         20 . The one or more computer-readable media of  claim 16 , wherein the computer executable instructions further cause the one or more processors to cache reads by the virtual machine from the image, and read, from the cache, subsequent reads from cached sectors.