rman备份类型及删除备份

环境：linux、oracle

1、备份的两种方式比较

copy 镜像拷贝，是数据文件的复制，大小和数据文件一样，并且只能存储在disk磁盘上。还原直接进行copy比较快

backup_piece 备份片，只备份用过的block，并且还进行压缩，空间使用量小。还原需要找各个block的位置相对copy要慢

2、RMAN备份的类型

Full backup 包含所有使用的数据文件块
Level 0增量备份等价于标记为0的full backup                 rman>backup incremental level 0 database;
level1的累计增量备份 包含上次0级别增量备份以来修改的部分      rman>backup incremental level 1 cumulative database;
level1的差异增量备份 包含上次增量备份以来修改的的部分         rman>backup incremental level 1 database;

下图为累积增量和差异增量区别

注意：如果没有执行0级备份，直接执行1级备份，rman会自动执行一次0级备份

3、删除过期和无效备份

CROSSCHECK: Verifies the status of backups and copies recorded in the RMAN repository against media such as disk or tape
DELETE EXPIRED: Removes only files whose status in the  repository is EXPIRED    #备份保留策略时间、或数量外的备份
DELETE OBSOLETE: Deletes backups that are no longer needed                       #备份文件可能被os系统删除的备份

RMAN> report obsolete;
RMAN retention policy will be applied to the command
RMAN retention policy is set to redundancy 1
no obsolete backups found
RMAN> delete expired backupset;
RMAN> delete noprompt obsolete;       #加上noprompt参数表示不用交互，直接删除

rman备份类型及删除备份

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