You can replace an entire nCache file with a new simulation, or you can strategically replace individual cache frames in an nCache file. For example, you can improve an object’s cached simulation by resimulating specific frames and replacing only those frames in its nCache file.
After the simulation, a cache is created for the selected object, replacing its current cache at the time range specified in the Replace nCache Options or Replace Fluid Cache Options window.
After the simulation, a cache is created for the frame or range of frames specified in the Replace nCache Frame(s) Options or Replace Fluid Cache Frame(s) Options window, replacing your object’s current cache at the specified time range, and backups of the original unchanged cache and description files are generated (named backup#_originalCacheName by default). This is required for undo operations.
See nCache > Replace Cache Frame or Fluid nCache > Replace Cache Frame.
To undo a replace nCache frames operation
If Delete backup files was on when you replaced your nCache frames, then you cannot undo the Replace operation because the frames that were replaced were also deleted from disk.
When you replace nCache frames, backup files of the original cache data are automatically generated and named by prefixing the original cache file names with backup_, backup1_ and so on. To undo a replace nCache frames operation, the backup files that were generated need to be renamed to the original file names. For example, to undo a replace nCache frames operation on an nCache named Cape, you would rename its backup_Cape.xml and backup_Cape.mc backup files to Cape.xml and Cape.mc.
When you replace nCache frames on a One File Per Frame cache, only the frames that are replaced are backed up. To undo a replace nCache frames operation on a One File Per Frame cache, the backup frame files that were generated need to be renamed to the original frame file names. For example, to undo a replace nCache frames operation on the nCloth One File Per Frame caches named CapeFrame1, CapeFrame2, and CapeFrame3, you would rename their backup_Cape.xml file to Cape.xml, and the replaced frame backup files backup_CapeFrame1.mc, backup_CapeFrame2.mc, and backup_CapeFrame3.mc to CapeFrame1.mc, CapeFrame2.mc, and CapeFrame3.mc.