[centos] softraid 복구 테스트

centos 설치시 boot 영역과 스왑등 모든 파티션을 Raid1로 구축하여 확인및 복구하는 명령어입니다.

복구 테스트 (강제적으로 레이드1의 0마운트 해제 하자)

# mdadm --manage /dev/md0 --fail /dev/sdb1

# mdadm --manage /dev/md1 --fail /dev/sdb2

# mdadm --manage /dev/md2 --fail /dev/sdb3

# mdadm --manage /dev/md0 --remove /dev/sdb1

# mdadm --manage /dev/md1 --remove /dev/sdb2

# mdadm --manage /dev/md2 --remove /dev/sdb3

# shutdown -h now

# cat /proc/mdstat

아래와 같이 장애를 볼 수 있다.

# cat /proc/mdstat

Personalities : [raid1]

md2 : active raid1 sda3[0]

      4594496 blocks [2/1] [U_]

md1 : active raid1 sda2[0]

      497920 blocks [2/1] [U_]

md0 : active raid1 sda1[0]

      144448 blocks [2/1] [U_]

unused devices: <none>

server1:~#

The output of

fdisk -l

should look as follows:

# fdisk -l

Disk /dev/sda: 5368 MB, 5368709120 bytes

255 heads, 63 sectors/track, 652 cylinders

Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System

/dev/sda1   *           1          18      144553+  fd  Linux raid autodetect

/dev/sda2              19          80      498015   fd  Linux raid autodetect

/dev/sda3              81         652     4594590   fd  Linux raid autodetect

Disk /dev/sdb: 5368 MB, 5368709120 bytes

255 heads, 63 sectors/track, 652 cylinders

Units = cylinders of 16065 * 512 = 8225280 bytes

Disk /dev/sdb doesn't contain a valid partition table

Disk /dev/md0: 147 MB, 147914752 bytes

2 heads, 4 sectors/track, 36112 cylinders

Units = cylinders of 8 * 512 = 4096 bytes

Disk /dev/md0 doesn't contain a valid partition table

Disk /dev/md1: 509 MB, 509870080 bytes

2 heads, 4 sectors/track, 124480 cylinders

Units = cylinders of 8 * 512 = 4096 bytes

Disk /dev/md1 doesn't contain a valid partition table

Disk /dev/md2: 4704 MB, 4704763904 bytes

2 heads, 4 sectors/track, 1148624 cylinders

Units = cylinders of 8 * 512 = 4096 bytes

Disk /dev/md2 doesn't contain a valid partition table

# sfdisk -d /dev/sda | sfdisk /dev/sdb 

Checking that no-one is using this disk right now ...

OK

Disk /dev/sdb: 652 cylinders, 255 heads, 63 sectors/track

sfdisk: ERROR: sector 0 does not have an msdos signature

 /dev/sdb: unrecognized partition table type

Old situation:

No partitions found

New situation:

Units = sectors of 512 bytes, counting from 0

   Device Boot    Start       End   #sectors  Id  System

/dev/sdb1   *        63    289169     289107  fd  Linux raid autodetect

/dev/sdb2        289170   1285199     996030  fd  Linux raid autodetect

/dev/sdb3       1285200  10474379    9189180  fd  Linux raid autodetect

/dev/sdb4             0         -          0   0  Empty

Successfully wrote the new partition table

superblock 설정 작업

# mdadm --zero-superblock /dev/sdb1

# mdadm --zero-superblock /dev/sdb2

# mdadm --zero-superblock /dev/sdb3

소프트 레이드 드라이브인  mdX 에 복원

  

# mdadm -a /dev/md0 /dev/sdb1

# mdadm -a /dev/md1 /dev/sdb2

# mdadm -a /dev/md2 /dev/sdb3

아래와 같이 리커버리되는 상황을 볼 수 있다.

# cat /proc/mdstat

Personalities : [raid1]

md2 : active raid1 sdb3[2] sda3[0]

      4594496 blocks [2/1] [U_]

      [======>..............]  recovery = 30.8% (1416256/4594496) finish=0.6min speed=83309K/sec

md1 : active raid1 sdb2[1] sda2[0]

      497920 blocks [2/2] [UU]

md0 : active raid1 sdb1[1] sda1[0]

      144448 blocks [2/2] [UU]

unused devices: <none>

server1:~#

아래와 같이 안정적으로 동기화 작업이 마쳤다.

# cat /proc/mdstat

Personalities : [raid1]

md2 : active raid1 sdb3[1] sda3[0]

      4594496 blocks [2/2] [UU]

md1 : active raid1 sdb2[1] sda2[0]

      497920 blocks [2/2] [UU]

md0 : active raid1 sdb1[1] sda1[0]

      144448 blocks [2/2] [UU]

6 Preparing GRUB 복구(부트 레코드를 복구 하지 않는다면 나중에 복구된 HDD로는 부팅이 되지 않는다.)

grub

grub> root (hd0,0)

 Filesystem type is ext2fs, partition type 0x83

grub> setup (hd0)

 Checking if "/boot/grub/stage1" exists... no

 Checking if "/grub/stage1" exists... yes

 Checking if "/grub/stage2" exists... yes

 Checking if "/grub/e2fs_stage1_5" exists... yes

 Running "embed /grub/e2fs_stage1_5 (hd0)"...  15 sectors are embedded.

succeeded

 Running "install /grub/stage1 (hd0) (hd0)1+15 p (hd0,0)/grub/stage2 /grub/menu.lst"... succeeded

Done.

grub> root (hd1,0)

 Filesystem type is ext2fs, partition type 0xfd

grub> setup (hd1)

 Checking if "/boot/grub/stage1" exists... no

 Checking if "/grub/stage1" exists... yes

 Checking if "/grub/stage2" exists... yes

 Checking if "/grub/e2fs_stage1_5" exists... yes

 Running "embed /grub/e2fs_stage1_5 (hd1)"...  15 sectors are embedded.

succeeded

 Running "install /grub/stage1 (hd1) (hd1)1+15 p (hd1,0)/grub/stage2 /grub/menu.lst"... succeeded

Done.

quit

Now, back on the normal shell, we reboot the system and hope that it boots ok from our RAID arrays:

reboot