Switch -SV - create independent solid volumes
By default WinRAR tries to reset solid statistics as soon as possible when starting a new volume, but only if enough data was packed after a previous reset (at least a few megabytes). This switch forces WinRAR to ignore packed data size and attempt to reset statistics for volumes of any size. It decreases compression, but increases chances to extract a part of data if one of several solid volumes in a volume set was lost or damaged.
Note that sometimes WinRAR cannot reset statistics even using this switch. For example, it cannot be done when compressing one large file split between several volumes. WinRAR is able to reset solid statistics only between separate files, but not inside of single file.
Ignored if used when creating a non-volume archive.
Also you may put this option to RAR environment variable to use it in WinRAR shell.