前面介绍了Oracle的基本参数，从这节开始讲其他的参数，参数从v$parameter中提取 基本参数请看如下链接: [http://www.zhaibibei.cn/oralce/oracle-parameter/](http://www.zhaibibei.cn/oralce/oracle-parameter/) 如无特殊说明数据库版本为11.2 **FAST_START_MTTR_TARGET** [image:484 size:orig] 1. 参数类型:整型 3. 默认值:0 3. 修改:修改不需要重启数据库 4. 取值范围 0到3600 5. 基础参数:否 6. RAC中各节点该值可以不一样，也可以在线改 ------ **取值意义** 该参数可以使你指定一个实例做crash recovery时需要的时间，单位为秒 指定时该参数被LOG_CHECKPOINT_INTERVAL覆盖 **MTTR** MTTR(mean time to recover),开启对系统影响较小 Oracle 时刻预估恢复时间并进行checkpoint以达到参数的值 **设置MTTR ** 设置如下参数开启MTTR ``` STATISTICS_LEVEL = TYPICAL FAST_START_MTTR_TARGET > 0 ``` 查询视图查看MTTR 建议值 ``` SELECT TARGET_MTTR, ESTIMATED_MTTR, CKPT_BLOCK_WRITES FROM V$INSTANCE_RECOVERY; ``` [image:486 size:orig] 比较TARGET_MTTR值和参数的值，差距较大时调整 同时需要将如下参数设置下为0 ``` LOG_CHECKPOINT_TIMEOUT = 0 LOG_CHECKPOINT_INTERVAL = 0 FAST_START_IO_TARGET = 0 ``` **关闭MTTR** ``` FAST_START_MTTR_TARGET =0 LOG_CHECKPOINT_INTERVAL = 200000 ``` --------- **实际截图：** [image:485 size:orig] ---------- **参考链接** [https://docs.oracle.com/cd/E18283_01/server.112/e17110/initparams086.htm](https://docs.oracle.com/cd/E18283_01/server.112/e17110/initparams086.htm) [https://www.akadia.com/services/ora_checkpoint_tuning.html](https://www.akadia.com/services/ora_checkpoint_tuning.html) --- 下期参数 **log_checkpoints_to_alert**