Can Weak Backup & Recovery Skills Cost You Your Probation?

Database Failure Types

user process failure – handled automatically by PMON

instance failure – handled automatically by SMON

user errors – require DBA intervention via backup and restore

media failure – must be addressed with backup and redo‑log recovery

Backup and Recovery Classifications

Logical backup

Traditional export/import (exp/imp) and Data Pump (expdp/impdp) capture object states at a point in time

Target object‑oriented logical backups; cannot be used for media failure recovery because recovery consists only of a restore step without a recover phase

Physical backup

Designed for media failure scenarios

Manual OS‑level backup (UMAN) uses operating‑system commands to copy files and then applies archived redo logs for recovery

Automated backup using Oracle RMAN performs both restore and recovery automatically

Physical backups can be consistent (cold) or inconsistent (hot); a complete strategy should prioritize physical backups and use logical backups as a supplement for critical tables

Flashback Technology

Uses undo data or flashback logs for rapid logical recovery

Provides logical recovery at various granularity levels

Oracle 11g supports seven flashback methods; the fast‑recovery area is relevant only to flashback database

Full vs. Partial Recovery

Full recovery: uses a complete or incremental backup to restore a datafile to the last committed state before failure, avoiding data loss

Partial recovery: combines a full backup with archived logs to restore the database to a specific point in time or SCN, which may involve data loss

Backup Strategy

Weekly schedule – level‑0 full backup every Sunday; level‑1 incremental backups Monday through Saturday

Retention policy – redundancy 2

Enable automatic control‑file backup

RMAN> show all;</code>
<code>CONFIGURE RETENTION POLICY TO REDUNDANCY 2;</code>
<code>CONFIGURE CONTROLFILE AUTOBACKUP ON;

Backup Script Example

#!/bin/bash
export ORACLE_BASE=/u01/app/oracle
export ORACLE_HOME=$ORACLE_BASE/product/11.2.0/dbhome_1
export ORACLE_SID=PROD
PATH=/usr/sbin:$PATH; export PATH
PATH=$ORACLE_HOME/bin:$PATH; export PATH
rman target / << EOF
run{
  crosscheck backup;
  allocate channel c1 device type disk;
  allocate channel c2 device type disk;
  backup incremental level 0 database format '/u01/backup/rman/db_%U.bak' plus archivelog format '/u01/backup/rman/ar_%U.bak';
  backup current controlfile format '/u01/backup/rman/ctl_%U.bak';
  report obsolete device type disk;
  delete noprompt obsolete device type disk;
  delete noprompt expired backup device type disk;
  release channel c1;
  release channel c2;
}
EOF
exit

Make the scripts executable:

chmod a+x /home/oracle/scripts/rman_level0.sh
chmod a+x /home/oracle/scripts/rman_level1.sh

Scheduling with crontab

0 * * * * /home/oracle/scripts/rman_level0.sh >> /u01/backup/rman/PROD_rman_L0_`date +%Y%m%d_%H%M%S`.log 2>&1
15,30,45 * * * * /home/oracle/scripts/rman_level1.sh >> /u01/backup/rman/PROD_rman_L1_`date +%Y%m%d_%H%M%S`.log 2>&1

Verify Backup Status

select a.TIME_TAKEN_DISPLAY as "用时",
       a.INPUT_BYTES_DISPLAY as "大小",
       a.INPUT_BYTES_PER_SEC_DISPLAY as "速度",
       a.INPUT_TYPE as "备份类型",
       to_char(start_time,'day') day1,
       to_char(start_time,'yyyy-mm-dd hh24:mi:ss') as "开始时间",
       to_char(end_time,'yyyy-mm-dd hh24:mi:ss') as "结束时间",
       output_device_type,
       status,
       input_type
from V$RMAN_BACKUP_JOB_DETAILS a;

Illustrative Diagrams