删除分区 oracle asm disk 恢复

惜分飞 — Sun, 04 Jul 2021 08:15:38 +0000

接到一个朋友数据库故障请求case.大概操作是这样的:有一个39T的lun,通过parted分了15个分区,给oracle asm使用创建磁盘组data4,然后分了4个分区做成data5(由于ausize写错误了),删除掉磁盘组和这四个分区.然后重新分配了6个分区,并且使用最后5个分区创建了data5磁盘组.使用了一段时间之后,由于oracle空间不足,检查的时候误以为这个lun就前面15个分区使用,人工把后面的6个分区给删除了,并且创建了4个新分区,然后发现数据库crash了,发现误删除了在使用的分区.然后又把新创建的4个分区给删除了.接手该故障的时候,这个39T lun的分区信息如下

[root@node1 linux64]# parted /dev/mapper/36000d31003d39e000000000000000004
GNU Parted 2.1
Using /dev/mapper/36000d31003d39e000000000000000004
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) print                                                            
Model: Linux device-mapper (multipath) (dm)
Disk /dev/mapper/36000d31003d39e000000000000000004: 39.6TB
Sector size (logical/physical): 512B/4096B
Partition Table: gpt

Number  Start   End     Size    File system  Name         Flags
 1      2097kB  2000GB  2000GB               asmdata4-1
 2      2000GB  4000GB  2000GB               asmdata4-2
 3      4000GB  6000GB  2000GB               asmdata4-3
 4      6000GB  8000GB  2000GB               asmdata4-4
 5      8000GB  10.0TB  2000GB               asmdata4-5
 6      10.0TB  12.0TB  2000GB               asmdata4-6
 7      12.0TB  14.0TB  2000GB               asmdata4-7
 8      14.0TB  16.0TB  2000GB               asmdata4-8
 9      16.0TB  18.0TB  2000GB               asmdata4-9
10      18.0TB  20.0TB  2000GB               asmdata4-10
11      20.0TB  22.0TB  2000GB               asmdata4-11
12      22.0TB  24.0TB  2000GB               asmdata4-12
13      24.0TB  26.0TB  2000GB               asmdata4-13
14      26.0TB  28.0TB  2000GB               asmdata4-14
15      28.0TB  30.0TB  2000GB               asmdata4-15

客户正常使用情况下,这个lun上面相关分区的asm disk信息

 SQL> CREATE DISKGROUP DATA4 EXTERNAL REDUNDANCY  DISK 
'/dev/mapper/36000d31003d39e000000000000000004p1' SIZE 1907346M ,
 '/dev/mapper/36000d31003d39e000000000000000004p2' SIZE 1907350M ,
 '/dev/mapper/36000d31003d39e000000000000000004p3' SIZE 1907348M ,
 '/dev/mapper/36000d31003d39e000000000000000004p4' SIZE 1907348M ,
 '/dev/mapper/36000d31003d39e000000000000000004p5' SIZE 1907350M  
ATTRIBUTE 'compatible.asm'='11.2.0.0.0','au_size'='8M' /* ASMCA */ 

SQL> ALTER DISKGROUP DATA4 ADD  DISK 
'/dev/mapper/36000d31003d39e000000000000000004p10' SIZE 1907348M ,
'/dev/mapper/36000d31003d39e000000000000000004p6' SIZE 1907348M ,
'/dev/mapper/36000d31003d39e000000000000000004p7' SIZE 1907348M ,
'/dev/mapper/36000d31003d39e000000000000000004p8' SIZE 1907350M ,
'/dev/mapper/36000d31003d39e000000000000000004p9' SIZE 1907348M /* ASMCA */ 

SQL> ALTER DISKGROUP DATA4 ADD  DISK 
'/dev/mapper/36000d31003d39e000000000000000004p11' SIZE 1907348M ,
'/dev/mapper/36000d31003d39e000000000000000004p12' SIZE 1907350M ,
'/dev/mapper/36000d31003d39e000000000000000004p13' SIZE 1907348M ,
'/dev/mapper/36000d31003d39e000000000000000004p14' SIZE 1907348M ,
'/dev/mapper/36000d31003d39e000000000000000004p15' SIZE 1907350M /* ASMCA */ 

SQL> CREATE DISKGROUP DATA5 EXTERNAL REDUNDANCY  DISK 
'/dev/mapper/36000d31003d39e000000000000000004p17' SIZE 1716614M ,
'/dev/mapper/36000d31003d39e000000000000000004p18' SIZE 1716614M ,
'/dev/mapper/36000d31003d39e000000000000000004p19' SIZE 1716614M ,
'/dev/mapper/36000d31003d39e000000000000000004p20' SIZE 1716614M ,
'/dev/mapper/36000d31003d39e000000000000000004p21' SIZE 1621246M  
ATTRIBUTE 'compatible.asm'='11.2.0.0.0','au_size'='4M' /* ASMCA */

基于客户现在的情况,data4中的所有分区都正常,主要是要找出来data5中的5个分区的数据.因为客户不确定p16分区大小,导致后续的5个分区起始位置不好定位.从而使得恢复无法进行.通过shell脚本结合kfed尝试定位asm disk header信息

#!/bin/bash
j=xxxxxxxxxxx
for ((i=xxxxxx; i<=j; i++))
do
 echo "-----$i--------" >> /home/get_au1.txt
 kfed read /dev/mapper/36000d31003d39e000000000000000004 aun=$i |
 > grep  "kfdhdb.dskname:              DATA" >> /home/get_au.txt
done

结果发现无法获取到结果,通过分析发现这里由于lun过大，导致aun值过大,从而使得kfed溢出无法读取到正常值.根据parted的特性,人工dd部分block进行分析

[root@node1 bak]# kfed read xifenfei.dd aun=134|more
kfbh.endian:                          1 ; 0x000: 0x01
kfbh.hard:                          130 ; 0x001: 0x82
kfbh.type:                            1 ; 0x002: KFBTYP_DISKHEAD
kfbh.datfmt:                          1 ; 0x003: 0x01
kfbh.block.blk:                       0 ; 0x004: blk=0
kfbh.block.obj:              2147483648 ; 0x008: disk=0
kfbh.check:                  3357988283 ; 0x00c: 0xc826d5bb
kfbh.fcn.base:                        0 ; 0x010: 0x00000000
kfbh.fcn.wrap:                        0 ; 0x014: 0x00000000
kfbh.spare1:                          0 ; 0x018: 0x00000000
kfbh.spare2:                          0 ; 0x01c: 0x00000000
kfdhdb.driver.provstr:         ORCLDISK ; 0x000: length=8
kfdhdb.driver.reserved[0]:            0 ; 0x008: 0x00000000
kfdhdb.driver.reserved[1]:            0 ; 0x00c: 0x00000000
kfdhdb.driver.reserved[2]:            0 ; 0x010: 0x00000000
kfdhdb.driver.reserved[3]:            0 ; 0x014: 0x00000000
kfdhdb.driver.reserved[4]:            0 ; 0x018: 0x00000000
kfdhdb.driver.reserved[5]:            0 ; 0x01c: 0x00000000
kfdhdb.compat:                186646528 ; 0x020: 0x0b200000
kfdhdb.dsknum:                        0 ; 0x024: 0x0000
kfdhdb.grptyp:                        1 ; 0x026: KFDGTP_EXTERNAL
kfdhdb.hdrsts:                        3 ; 0x027: KFDHDR_MEMBER
kfdhdb.dskname:              DATA5_0000 ; 0x028: length=10
kfdhdb.grpname:                   DATA5 ; 0x048: length=5
kfdhdb.fgname:               DATA5_0000 ; 0x068: length=10
kfdhdb.capname:                         ; 0x088: length=0
kfdhdb.crestmp.hi:             33116450 ; 0x0a8: HOUR=0x2 DAYS=0x9 MNTH=0x4 YEAR=0x7e5
kfdhdb.crestmp.lo:            477378560 ; 0x0ac: USEC=0x0 MSEC=0x10e SECS=0x7 MINS=0x7
kfdhdb.mntstmp.hi:             33116450 ; 0x0b0: HOUR=0x2 DAYS=0x9 MNTH=0x4 YEAR=0x7e5
kfdhdb.mntstmp.lo:            486256640 ; 0x0b4: USEC=0x0 MSEC=0x2ec SECS=0xf MINS=0x7
kfdhdb.secsize:                     512 ; 0x0b8: 0x0200
kfdhdb.blksize:                    4096 ; 0x0ba: 0x1000
kfdhdb.ausize:                  4194304 ; 0x0bc: 0x00400000
kfdhdb.mfact:                    454272 ; 0x0c0: 0x0006ee80
kfdhdb.dsksize:                  429153 ; 0x0c4: 0x00068c61
kfdhdb.pmcnt:                         2 ; 0x0c8: 0x00000002

顺利找到了data5中的第一块磁盘,而且确定了起始位置,然后构造相关的dd语句把分区的数据dd到一个新磁盘中

dd if=/dev/mapper/36000d31003d39e000000000000000004 bs=4M skip=xxxxx count=429153 of=/dev/sdu

然后通过kfed查看数据

通过类似方法依次处理,最终把5块asm disk全部找到,并且顺利dd到新的磁盘中.尝试启动crs,并mount data5

data5 磁盘组mount成功之后,数据库顺利启动,实现lun中删除分区之后,asm磁盘组数据完美恢复

这次运气还不错,仅仅是对lun的分区使用了parted进行了删除和创建等操作,没有格式化文件系统和做成新的asm disk,不然数据会有一部分丢失.对于有部分破坏的分区,需要通过底层碎片的方法进行最大限度抢救数据.参考类似文档:
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删除分区 oracle asm disk 恢复