Differences between ROW and COW of the OceanStor V3 Series
Redirect-on-write (ROW) retains old data for snapshots. Unlike copy-on-write (COW), ROW uses one less write operation. However, for ROW, fragments are generated after data is read and written for a long period. As a result, consecutive spaces cannot be allocated to multiple sequential I/Os or the I/Os will become random. You can optimize the working mechanism by running fragment management in the background.