??????LGWR??DBWR?????????￡?Oracle???????????????????????????????????????Oracle???棬???????????????????????????????????????????????????????

????1?????????

??????Oracle8i???????????????????????????????????????????????????е????????д???????????????У????????????????????????????????????????????????8i????????????????????2??????

??????1??DBA??????alter system checkpoint??????

??????2???????????shutdown??immediate??transcational??normal????

???????????????????е?????????д??????IO???????????????????????Oracle??8i????????????????????

????2??????????

????Oracle ??8i??????????????????????????????????????浱????е??????????????DBWR ??????????ж??????????д??????????С???????а?????????????????????????????????????????????RBA??Redo Block Address???????????????????????????????????????????????η????????????????????????????????????????????????????Σ????????????????λ?????????????????????????????RBA??????????????????????????д????DBWR?????????????????????д????????????????λ????????????????CKPT???????????????м???????λ???????Instance Recovery????????????????????????????????????????heartbeat????????λ?÷????????Oracle???????4????????????????λ?ú????????????????????????????????????????????????4?????????????????????????????????????????????4?????????????????????????????????????????????????????

??????1??fast_start_io_target

?????ò????????????????Instance Recovery??????????????IO???????????v$filestat??AVGIOTIM?????????????????????????????Instance Crash???????10???????????????OS??IO????500?????????????????Instance Recovery????????????500*10*60=30??000??IO???????????????fast_start_io_target????? 30000??

??????2??fast_start_mttr_target

???????????????????fast_start_io_target ?????????λ?????鷳??Oracle?????????????9i????????? fast_start_mttr_target?????????????????????????Instance Recovery????????????λ???????????????????????????????е?mttr??mean time to recovery???д?????????е????????????fast_start_mttr_target?????600?????????? fast_start_mttr_target??fast_start_io_target???????????????Ч????9i?? fast_start_io_target?????????Oracle??????

??????3??log_checkpoint_timeout

?????ò?????????????λ?ú????????????β?????????????????λ????????????1800??

??????4??log_checkpoint_interval

?????ò???????????λ?ú?????????β????????????????????OS??????

??????5??90% OF SMALLEST REDO LOG

????????????4?????????????Oracle??????????????????????β???90%??λ?????????λ?á??????????????У?????????????????λ?????????????Oracle???????????β???????λ??????????λ?á?