I tried to restore database from the backup I took before ,everything worked well . But when I check the volume on where database is created ,I see that the volume increases from 63Gb( before restore) to 70 GB (after restore) .I really don't know why the volume is increased abnormally ?
when you are doing restore some files can be overwritten and can cause higher ratio change. The best example of that is for example Oracle resetlogs operation which rewrites whole Oracle active redo log files.
If something would go bad then perhaps you could end up in host side restore, which could result in overwriting all Oracle data files (instead of revering the vol snaps/LUN snaps on the storage directly)... (this depends on the storage layout used).
In short: it depends on the way which SMO choose to restore the database (storage side, host side, etc), there are too many factors and not enough data.