### 1. 内容概述 ```c oracle asm dd格式化50M以内，oracle metadata信息会被格式化，oracle磁盘组无法mount， 存储在asm中的数据面临丢失的风险，针对该场景本文使用数据块重构方法进行恢复。 ``` ### 2. 环境准备 #### 创建asm磁盘组 ```c SQL> create diskgroup test external redundancy disk '/dev/oracleasm/disks/arch1'; Diskgroup created. SQL> ``` #### 创建数据文件 ```c SQL> create tablespace tt666 datafile '+test' size 100M; Tablespace created. SQL> ``` #### 创建测试表 ```c SQL> create table t_666 tablespace tt666 as select * from obj$; select count(1) from t_666; Table created. SQL> COUNT(1) ---------- 86420 SQL> ``` ### 3. 破坏asm磁盘 ```c dd if=/dev/zero of=/dev/oracleasm/disks/arch1 bs=1M count=50 conv=notrunc ``` ### 4. 检查asm磁盘组 ```c [grid@snyxdb1 ~]$ asmcmd lsdg State Type Rebal Sector Block AU Total_MB Free_MB Req_mir_free_MB Usable_file_MB Offline_disks Voting_files Name MOUNTED EXTERN N 512 4096 1048576 3072 2977 0 2977 0 N ARCH/ MOUNTED EXTERN N 512 4096 1048576 30720 16942 0 16942 0 Y DATA/ [grid@snyxdb1 ~]$ ``` #### 检查asm日志 ```c NOTE: cache deleting context for group TEST 3/0x41a9310d GMON dismounting group 3 at 33 for pid 33, osid 79556 NOTE: Disk TEST_0000 in mode 0x7f marked for de-assignment SUCCESS: diskgroup TEST was dismounted Fri Jan 22 10:08:43 2021 NOTE: diskgroup resource ora.TEST.dg is offline SUCCESS: alter diskgroup TEST dismount force /* ASM SERVER:1101607181 */ SUCCESS: ASM-initiated MANDATORY DISMOUNT of group TEST ``` #### 检查数据库状态 ```c [oracle@snyxdb1 ~]$ sqlplus / as sysdba SQL*Plus: Release 11.2.0.4.0 Production on Fri Jan 22 10:13:03 2021 Copyright (c) 1982, 2013, Oracle. All rights reserved. Connected to an idle instance. SQL> startup ORACLE instance started. Total System Global Area 1185853440 bytes Fixed Size 2252664 bytes Variable Size 436207752 bytes Database Buffers 721420288 bytes Redo Buffers 25972736 bytes Database mounted. ORA-01157: cannot identify/lock data file 18 - see DBWR trace file ORA-01110: data file 18: '+TEST/epmsn/datafile/tt666.256.1062497259' SQL> ``` ### 5. 重新mount asm磁盘组 ```c SQL> alter diskgroup test mount; alter diskgroup test mount * ERROR at line 1: ORA-15032: not all alterations performed ORA-15017: diskgroup "TEST" cannot be mounted ORA-15040: diskgroup is incomplete SQL> ``` ### 6. scan asmdisk恢复数据文件 ```c [root@snyxdb1 xdul]# ./xdul xdul: Data Unload for Oracle version 1.1.1 Copyright(c) 2020 orastar.All rights reserved. Wechat: xidoublestr Email: 634025070@qq.com loading default config....... load config file 'config.txt' successful loading default control file ...... ts# fn rfn bsize blocks filename kscnbas_484 kcvcptim_496 kcvfhrlc_112 kscnbas_116 ---- ---- ---- ----- -------- -------------------------------------------- -------- -------- -------- -------- 16 14 14 8192 1280 /home/grid/star2.dbf 766cb2 3f5418ae 3c54493e e2006 load control file 'control.txt' successful XDUL>scan asmdisk XDUL>extract datafile input extract file_no:18 [root@snyxdb1 xdul]# ls -ltr data/ total 102408 -rw-r--r-- 1 root root 104865792 Jan 22 10:28 18.dbf <-- extract生成数据文件 [root@snyxdb1 xdul]# ``` ### 7. dbv检查数据文件 ```c [oracle@snyxdb1 data]$ dbv file=18.dbf DBVERIFY: Release 11.2.0.4.0 - Production on Fri Jan 22 10:30:12 2021 Copyright (c) 1982, 2011, Oracle and/or its affiliates. All rights reserved. DBVERIFY - Verification starting : FILE = /home/oracle/xdul/data/18.dbf DBVERIFY - Verification complete Total Pages Examined : 12800 Total Pages Processed (Data) : 1068 Total Pages Failing (Data) : 0 Total Pages Processed (Index): 0 Total Pages Failing (Index): 0 Total Pages Processed (Other): 127 Total Pages Processed (Seg) : 0 Total Pages Failing (Seg) : 0 Total Pages Empty : 11605 Total Pages Marked Corrupt : 0 Total Pages Influx : 0 Total Pages Encrypted : 0 Highest block SCN : 7764758 (0.7764758) [oracle@snyxdb1 data]$ ``` ### 7. 重启数据库 ```c SQL> select name from v$datafile where file#=18; NAME -------------------------------------------------------------------------------- +TEST/epmsn/datafile/tt666.256.1062497259 SQL> alter database rename file '+TEST/epmsn/datafile/tt666.256.1062497259' to '/home/oracle/xdul/data/18.dbf'; Database altered. SQL> alter database open; Database altered. SQL> ``` ### 8. 验证测试数据 ```c SQL> select count(1) from t_666; COUNT(1) ---------- 86420 SQL> ```