I can see in the original server we only have one ldf file for that database, it is called mydb.ldf. we never deleted or added before.
But on the new server, when I move/restore, on the option tab, the file path is database default location, the file name one is mydb.mdf, the log file is mydb_1.ldf.
I think it may try to create the same name, only extensions are different. Since there is already a file with the same name, it tried to create _1 file, instead of _log.
I didn't see this before. The only difference is the new server is a windows 2008, the old OS is windows 2003.
The sql server version are the same though.
I think I will just have to manually change the name to _log. Thanks