1.自9i始，系统默认以spfile为启动文件。
Path(NT): $oracle_home\database
Path(Unix): $oracle_home/dbs
2.启动文件查找次序为：spfile(sid).ora-->spfile.ora-->init(sid).ora
3.可以通过Alter System来修改spfile
如： alter system set log_archive_start=true scope=spfile ( or memory/both)
4.间接修改spfile
1) edit pfile
2) startup pfile='../initsid.ora'
3) create spfile from pfile
5.从autobackup恢复spfile
例：
RMAN> CONFIGURE CONTROLFILE AUTOBACKUP ON;
RMAN> run
2> {
3> allocate channel ch1 type disk format='/tmp/archive%t.arc';
4> backup archivelog all delete all input;
5> release channel ch1;
6> }
RMAN> restore spfile to '/tmp/spfile.ora' from autobackup;
