Capturing post-snapshot quiescence writes in an image backup

Abstract

Capturing post-snapshot quiescence writes in an image backup. In one example embodiment, a method for capturing post-snapshot quiescence writes in an image backup may include taking a first snapshot of a source storage at a first point in time using a Volume Shadow Copy Service (VSS), identifying a first set of block positions of blocks that are allocated in the source storage at the first point in time, identifying a second set of block positions of blocks that are written to the first snapshot during post-snapshot quiescence of the first snapshot by the VSS or by one or more VSS writers, resulting in a first quiesced snapshot, calculating a third set of block positions by performing a Boolean OR operation on the first and second sets of block positions, and copying blocks in the third set of block positions from the first snapshot to a full image backup.

1 . A method for capturing post-snapshot quiescence writes in an image backup, the method comprising:
 taking a first snapshot of a source storage at a first point in time using a Volume Shadow Copy Service (VSS);   identifying a first set of block positions of blocks that are allocated in the source storage at the first point in time;   identifying a second set of block positions of blocks that are written to the first snapshot during post-snapshot quiescence of the first snapshot by the VSS or by one or more VSS writers, resulting in a first quiesced snapshot;   calculating a third set of block positions by performing a Boolean OR operation on the first set of block positions and the second set of block positions; and   copying blocks in the third set of block positions from the first quiesced snapshot to a full image backup.   
     
     
         2 . The method as recited in  claim 1 , further comprising:
 tracking a fourth set of block positions of blocks that are modified in the source storage between the first point in time and a second point in time;   taking a second snapshot of the source storage at the second point in time using the VSS;   identifying a fifth set of block positions of blocks that are allocated in the source storage at the second point in time;   identifying a sixth set of block positions of blocks that are written to the second snapshot during post-snapshot quiescence of the second snapshot by the VSS or by the one or more VSS writers, resulting in a second quiesced snapshot;   calculating a seventh set of block positions by performing a Boolean OR operation on the second set of block positions and the fourth set of block positions;   calculating an eighth set of block positions by performing a Boolean AND operation on the fifth set of block positions and the seventh set of block positions;   calculating a ninth set of block positions by performing a Boolean OR operation on the sixth set of block positions and the eighth set of block positions; and   copying blocks in the ninth set of block positions from the second quiesced snapshot to an incremental image backup.   
     
     
         3 . The method as recited in  claim 2 , wherein the identifying of the fifth set of block positions is performed by accessing a file system block allocation map (FSBAM) of the source storage that is stored in the second snapshot. 
     
     
         4 . The method as recited in  claim 2 , wherein the identifying of the fifth set of block positions is performed by accessing a file system block allocation map (FSBAM) of the source storage that is stored separately from the second snapshot. 
     
     
         5 . The method as recited in  claim 1 , wherein the one or more VSS writers include an Active Directory (AD) service. 
     
     
         6 . The method as recited in  claim 1 , wherein the one or more VSS writers include a Hyper-V hypervisor. 
     
     
         7 . The method as recited in  claim 1 , wherein the identifying of the first set of block positions is performed by accessing an FSBAM of the source storage that is stored in the first snapshot. 
     
     
         8 . The method as recited in  claim 1 , wherein the identifying of the first set of block positions is performed by accessing an FSBAM of the source storage that is stored separately from the first snapshot. 
     
     
         9 . One or more non-transitory computer-readable media storing one or more programs that are configured, when executed, to cause one or more processors to perform the method as recited in  claim 1 . 
     
     
         10 . A method for capturing post-snapshot quiescence writes in an image backup, the method comprising:
 taking a first snapshot of a source storage at a first point in time using a Volume Shadow Copy Service (VSS);   accessing a first file system block allocation map (FSBAM) of the source storage from the first point in time, the first FSBAM identifying block positions of blocks that are allocated in the source storage at the first point in time;   accessing a first quiescence map of the first snapshot, the first quiescence map identifying block positions of blocks that are written to the first snapshot during post-snapshot quiescence of the first snapshot by the VSS or by one or more VSS writers, resulting in a first quiesced snapshot;   calculating full backup block positions by performing a Boolean OR operation on the first FSBAM and the first quiescence map; and   copying blocks in the full backup block positions from the first quiesced snapshot to a full image backup.   
     
     
         11 . The method as recited in  claim 10 , further comprising:
 tracking, in a modify map, block positions of blocks that are modified in the source storage between the first point in time and a second point in time;   taking a second snapshot of the source storage at the second point in time using the VSS;   accessing a second FSBAM of the source storage from the second point in time, the second FSBAM identifying block positions of blocks that are allocated in the source storage at the second point in time;   accessing a second quiescence map of the second snapshot, the second quiescence map identifying block positions of blocks that are written to the second snapshot during post-snapshot quiescence of the second snapshot by the VSS or by the one or more VSS writers, resulting in a second quiesced snapshot;   calculating incremental backup block positions by performing a Boolean OR operation on the first quiescence map and the modify map, then performing a Boolean AND operation with the second FSBAM, and then performing a Boolean OR operation with the second quiescence map; and   copying blocks in the incremental backup block positions from the second quiesced snapshot to an incremental image backup.   
     
     
         12 . The method as recited in  claim 11 , wherein the second FSBAM is stored in the second snapshot. 
     
     
         13 . The method as recited in  claim 11 , wherein the second FSBAM is stored separately from the second snapshot. 
     
     
         14 . The method as recited in  claim 11 , wherein the incremental image backup is a ShadowProtect Incremental (SPI) image backup. 
     
     
         15 . The method as recited in  claim 10 , wherein the one or more VSS writers include an Active Directory (AD) service. 
     
     
         16 . The method as recited in  claim 10 , wherein the one or more VSS writers include a Hyper-V hypervisor. 
     
     
         17 . The method as recited in  claim 10 , wherein the first FSBAM is stored in the first snapshot. 
     
     
         18 . The method as recited in  claim 10 , wherein the first FSBAM is stored separately from the first snapshot. 
     
     
         19 . The method as recited in  claim 10 , wherein the full image backup is a ShadowProtect Full (SPF) image backup. 
     
     
         20 . One or more non-transitory computer-readable media storing one or more programs that are configured, when executed, to cause one or more processors to perform the method as recited in  claim 10 .