Linux II - 07. RAID 관리

Linux II - 07. RAID 관리

 

 

 

 - VMware 스냅샷 실시 - 'RAID 구성 이전'

 

login as: root
root@192.168.1.7's password:
Last login: Mon Feb 22 14:11:40 2016 from 192.168.1.1
[root@CentOS2 /root]#

 

 

 

 

1. RAID(Redudant Array of Inexpensive Disks)

 

여러개의 디스크를 하나의 디스크처럼 사용할 수 있도록 하며, 신뢰성과 성능을 향상시킬수 있는 저장 장치를 의미한다.

 

RAID 종류	장점	단점	단위
하드웨어 RAID	신뢰성 및 안정성 보장	고비용	디스크
소프트웨어 RAID	저비용	신뢰성 및 안정성 비보장	파티션

 

 

 

 

2. RAID 구성

 

[root@CentOS2 /root]# cat /proc/mdstat
Personalities :
unused devices: <none>

 

'mdadm' 명령어를 이용하여 RAID를 구성한다. 해당 명령어는 다음과 같다.

 

--create	RAID 구성	# mdadm --create /dev/md0
--detail	RAID 상태 상세 확인	# mdadm --detail /dev/md0
--remove	RAID 디스크 제거	# mdadm --manage /dev/md0 --remove /dev/sdc1
--add	RAID 디스크 추가	# mdadm --manage /dev/md0 --add /dev/sdc1
--fail	RAID 디스크 강제 장애	# mdadm --manage /dev/md0 --fail /dev/sdc1
-S (--stop)	RAID 정지	# mdadm --stop /dev/md0
-r (--remove)	RAID 제거	# mdadm -r /dev/md0

 

 

 

1) RAID 0 Volume (Stripe Volume)

 

최소 디스크 개수	2개 이상
장점	읽기/쓰기 속도가 빠르며, 디스크 가용율이 100%이다.
단점	이중화가 안되며, 디스크 하나가 손상되면 나머지 디스크에 저장된 데이터 전부를 사용할 수 없다.
비고

 

 

 

Ex1) RAID 0 구성

 

 - /dev/sdc1, /dev/sdd1, /dev/sde1 RAID 타입 파티션 생성

 

[root@CentOS2 /root]# fdisk /dev/sdc

WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
         switch off the mode (command 'c') and change display units to
         sectors (command 'u').

 

Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-204, default 1): 1
Last cylinder, +cylinders or +size{K,M,G} (1-204, default 204): 204

 

Command (m for help): t
Selected partition 1
Hex code (type L to list codes): fd
Changed system type of partition 1 to fd (Linux raid autodetect)

 

Command (m for help): p

Disk /dev/sdc: 213 MB, 213909504 bytes
64 heads, 32 sectors/track, 204 cylinders
Units = cylinders of 2048 * 512 = 1048576 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00024910

   Device Boot      Start         End      Blocks   Id  System
/dev/sdc1               1         204      208880   fd  Linux raid autodetect

 

Command (m for help): w
The partition table has been altered!

 

Calling ioctl() to re-read partition table.
Syncing disks.

[root@CentOS2 /root]# fdisk /dev/sdd

WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
         switch off the mode (command 'c') and change display units to
         sectors (command 'u').

 

Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-204, default 1): 1
Last cylinder, +cylinders or +size{K,M,G} (1-204, default 204): 204

 

Command (m for help): t
Selected partition 1
Hex code (type L to list codes): fd
Changed system type of partition 1 to fd (Linux raid autodetect)

 

Command (m for help): w
The partition table has been altered!

 

Calling ioctl() to re-read partition table.
Syncing disks.

[root@CentOS2 /root]# fdisk /dev/sde

WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
         switch off the mode (command 'c') and change display units to
         sectors (command 'u').

 

Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-204, default 1): 1
Last cylinder, +cylinders or +size{K,M,G} (1-204, default 204): 204

 

Command (m for help): t
Selected partition 1
Hex code (type L to list codes): fd
Changed system type of partition 1 to fd (Linux raid autodetect)

 

Command (m for help): w
The partition table has been altered!

 

Calling ioctl() to re-read partition table.
Syncing disks.
[root@CentOS2 /root]#

 

[root@CentOS2 /root]# fdisk -l /dev/sdc /dev/sdd /dev/sde | grep -i raid
/dev/sdc1               1         204      208880   fd  Linux raid autodetect
/dev/sdd1               1         204      208880   fd  Linux raid autodetect
/dev/sde1               1         204      208880   fd  Linux raid autodetect

 

 

 -  'mdadm' 명령어를 이용하여 RAID 0 구성 실시

[root@CentOS2 /root]# mdadm --create /dev/md0 --level=stripe --raid-devices=3 /dev/sdc1 /dev/sdd1 /dev/sde1
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md0 started.

 

[root@CentOS2 /root]# ls /dev/md0
/dev/md0

[root@CentOS2 /root]# fdisk -l /dev/md0

Disk /dev/md0: 637 MB, 637009920 bytes
2 heads, 4 sectors/track, 155520 cylinders
Units = cylinders of 8 * 512 = 4096 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 524288 bytes / 1572864 bytes
Disk identifier: 0x00000000

[root@CentOS2 /root]# mdadm --detail --scan -v
ARRAY /dev/md0 level=raid0 num-devices=3 metadata=1.2 name=CentOS2:0 UUID=d1e6afb4:770ed44d:bee91aad:46719986
   devices=/dev/sdc1,/dev/sdd1,/dev/sde1

[root@CentOS2 /root]# cat /proc/mdstat
Personalities : [raid0]
md0 : active raid0 sde1[2] sdd1[1] sdc1[0]
      622080 blocks super 1.2 512k chunks

unused devices: <none>

 

 

 - 파일 시스템 생성 및 마운트 실시

[root@CentOS2 /root]# mkfs.ext4 /dev/md0 1> /dev/null
mke2fs 1.41.12 (17-May-2010)

[root@CentOS2 /root]# mkdir /raid0

[root@CentOS2 /root]# mount /dev/md0 /raid0

[root@CentOS2 /root]# df -h /raid0
Filesystem      Size  Used Avail Use% Mounted on
/dev/md0        582M  468K  552M   1% /raid0

 

 

 - CentOS 6.x에서는 재부팅하면 RAID 볼륨 장치 번호가 변경된다. 변경되는 것을 방지하는 방법은 다음과 같다.

[root@CentOS2 /root]# mdadm --detail --scan -v 1> /etc/mdadm.conf    (RAID 설정 정보를 'mdadm.conf'에 저장)

 

 

 

Ex2) RAID 0 제거

 

[root@CentOS2 /root]# umount /dev/md0

 

[root@CentOS2 /root]# mdadm --stop /dev/md0

mdadm: stopped /dev/md0

[root@CentOS2 /root]# mdadm --zero-superblock /dev/sdc1 /dev/sdd1 /dev/sde1

[root@CentOS2 /root]# mdadm --examine /dev/sdc1 /dev/sdd1 /dev/sde1
mdadm: No md superblock detected on /dev/sdc1.
mdadm: No md superblock detected on /dev/sdd1.
mdadm: No md superblock detected on /dev/sde1.

[root@CentOS2 /root]# ls /dev/md0
ls: cannot access /dev/md0: 그런 파일이나 디렉터리가 없습니다

[root@CentOS2 /root]# df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/sda1        13G  4.4G  7.3G  38% /
tmpfs           495M  500K  494M   1% /dev/shm
/dev/sda3       477M  2.3M  449M   1% /home

 

 

 

 

 2) RAID 1 Volume (Mirror Volume)

 

최소 디스크 개수	2개 이상
장점	이중화가 가능하다.
단점	디스크 가용율이 50%이다.
비고	읽기 속도는 빠르지만, 쓰기 속도는 보통이다.

 

 

 

Ex1) RAID 1 구성

 

 - /dev/sdf1, /dev/sdg1 RAID 타입 파티션 생성

 

[root@CentOS2 /root]# fdisk /dev/sdf

WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
         switch off the mode (command 'c') and change display units to
         sectors (command 'u').

 

Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-204, default 1): 1
Last cylinder, +cylinders or +size{K,M,G} (1-204, default 204): 204

 

Command (m for help): t
Selected partition 1
Hex code (type L to list codes): fd
Changed system type of partition 1 to fd (Linux raid autodetect)

 

Command (m for help): w
The partition table has been altered!

 

Calling ioctl() to re-read partition table.
Syncing disks.
[root@CentOS2 /root]#

 

[root@CentOS2 /root]# fdisk /dev/sdg

WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
         switch off the mode (command 'c') and change display units to
         sectors (command 'u').

 

Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-204, default 1): 1
Last cylinder, +cylinders or +size{K,M,G} (1-204, default 204): 204

 

Command (m for help): t
Selected partition 1
Hex code (type L to list codes): fd
Changed system type of partition 1 to fd (Linux raid autodetect)

 

Command (m for help): w
The partition table has been altered!

 

Calling ioctl() to re-read partition table.
Syncing disks.
[root@CentOS2 /root]#

 

 

[root@CentOS2 /root]# fdisk -l /dev/sdf /dev/sdg | grep -i raid
/dev/sdf1               1         204      208880   fd  Linux raid autodetect
/dev/sdg1               1         204      208880   fd  Linux raid autodetect

 

 

 -  'mdadm' 명령어를 이용하여 RAID 1 구성 실시

 

[root@CentOS2 /root]# mdadm --create /dev/md1 --level=1 --raid-devices=2 /dev/sdf1 /dev/sdg1
mdadm: Note: this array has metadata at the start and
    may not be suitable as a boot device.  If you plan to
    store '/boot' on this device please ensure that
    your boot-loader understands md/v1.x metadata, or use
    --metadata=0.90
Continue creating array? y
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md1 started.

[root@CentOS2 /root]# ls /dev/md1
/dev/md1

[root@CentOS2 /root]# fdisk -l /dev/md1

Disk /dev/md1: 213 MB, 213712896 bytes
2 heads, 4 sectors/track, 52176 cylinders
Units = cylinders of 8 * 512 = 4096 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

[root@CentOS2 /root]# mdadm --detail -scan -v
ARRAY /dev/md1 level=raid1 num-devices=2 metadata=1.2 name=CentOS2:1 UUID=c957ee01:f985c8f8:8bfaad46:125b6bfb
   devices=/dev/sdf1,/dev/sdg1

[root@CentOS2 /root]# cat /proc/mdstat
Personalities : [raid0] [raid1]
md1 : active raid1 sdg1[1] sdf1[0]
      208704 blocks super 1.2 [2/2] [UU]

unused devices: <none>

 

 

 - 파일 시스템 생성 및 마운트 실시

[root@CentOS2 /root]# mkfs.ext4 /dev/md1 1> /dev/null
mke2fs 1.41.12 (17-May-2010)

[root@CentOS2 /root]# mkdir /raid1

[root@CentOS2 /root]# mount /dev/md1 /raid1

[root@CentOS2 /root]# df -h /raid1
Filesystem      Size  Used Avail Use% Mounted on
/dev/md1        194M  1.8M  182M   1% /raid1

 

 - CentOS 6.x에서는 재부팅하면 RAID 볼륨 장치 번호가 변경된다. 변경되는 것을 방지하는 방법은 다음과 같다.

[root@CentOS2 /root]# mdadm --detail --scan -v 1> /etc/mdadm.conf    (RAID 설정 정보를 'mdadm.conf'에 저장)

 

 

 

Ex2) RAID 1 제거

 

[root@CentOS2 /root]# umount /dev/md1

[root@CentOS2 /root]# mdadm --stop /dev/md1
mdadm: stopped /dev/md1

[root@CentOS2 /root]# mdadm --zero-superblock /dev/sdf1 /dev/sdg1

[root@CentOS2 /root]# mdadm --examine /dev/sdf1 /dev/sdg1
mdadm: No md superblock detected on /dev/sdf1.
mdadm: No md superblock detected on /dev/sdg1.

[root@CentOS2 /root]# ls /dev/md1
ls: cannot access /dev/md1: 그런 파일이나 디렉터리가 없습니다

[root@CentOS2 /root]# df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/sda1        13G  4.4G  7.3G  38% /
tmpfs           495M  500K  494M   1% /dev/shm
/dev/sda3       477M  2.3M  449M   1% /home

 

 

 

 

 3) RAID 5

 

최소 디스크 개수	3개 이상
장점	디스크 1개가 장애가 발생되어도, 데이터 복구가 가능하다.
단점	디스크를 가용할 수 있는 용량은 '전체 디스크 개수 -1' 을 해야 한다.
비고	성능이 그리 중요하지 않고 쓰기 작업이 많지 않은 다중 사용자 시스템에 적합하다.

 

 

 

Ex1) RAID 5 구성

 

 - /dev/sdc1, /dev/sdd1, /dev/sde1 RAID 타입 파티션 생성 확인

 
[root@CentOS2 /root]# fdisk -l /dev/sdc /dev/sdd /dev/sde | grep -i raid
/dev/sdc1               1         204      208880   fd  Linux raid autodetect
/dev/sdd1               1         204      208880   fd  Linux raid autodetect
/dev/sde1               1         204      208880   fd  Linux raid autodetect

 

 

 -  'mdadm' 명령어를 이용하여 RAID 5 구성 실시

[root@CentOS2 /root]# mdadm --create /dev/md5 --level=5 --raid-devices=3 /dev/sdc1 /dev/sdd1 /dev/sde1
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md5 started.

[root@CentOS2 /root]# ls /dev/md5
/dev/md5

[root@CentOS2 /root]# fdisk -l /dev/md5

Disk /dev/md5: 424 MB, 424673280 bytes
2 heads, 4 sectors/track, 103680 cylinders
Units = cylinders of 8 * 512 = 4096 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 524288 bytes / 1048576 bytes
Disk identifier: 0x00000000

[root@CentOS2 /root]# mdadm --detail --scan -v
ARRAY /dev/md5 level=raid5 num-devices=3 metadata=1.2 name=CentOS2:5 UUID=bf8908c0:0cb128dc:f4e87b4b:b6ffb981
   devices=/dev/sdc1,/dev/sdd1,/dev/sde1

[root@CentOS2 /root]# cat /proc/mdstat
Personalities : [raid0] [raid1] [raid6] [raid5] [raid4]
md5 : active raid5 sde1[3] sdd1[1] sdc1[0]
      414720 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/3] [UUU]

unused devices: <none>

 

 

 - CentOS 6.x에서는 재부팅하면 RAID 볼륨 장치 번호가 변경된다. 변경되는 것을 방지하는 방법은 다음과 같다.

 
[root@CentOS2 /root]# mdadm --detail --scan -v 1> /etc/mdadm.conf    (RAID 설정 정보를 'mdadm.conf'에 저장)

[root@CentOS2 /root]# cat /etc/mdadm.conf
ARRAY /dev/md5 level=raid5 num-devices=3 metadata=1.2 name=CentOS2:5 UUID=bf8908c0:0cb128dc:f4e87b4b:b6ffb981
   devices=/dev/sdc1,/dev/sdd1,/dev/sde1

 

 

 - 파일 시스템 생성 및 마운트 실시

[root@CentOS2 /root]# mkfs.ext4 /dev/md5 1> /dev/null
mke2fs 1.41.12 (17-May-2010)

[root@CentOS2 /root]# mkdir /raid5
[root@CentOS2 /root]# mount /dev/md5 /raid5

[root@CentOS2 /root]# df -h /raid5
Filesystem      Size  Used Avail Use% Mounted on
/dev/md5        385M  2.3M  362M   1% /raid5

 

 

 - /dev/sdd1 디스크 손상 실시

[root@CentOS2 /root]# ls /home
lost+found  user1  user2

[root@CentOS2 /root]# cp -rp /home/* /raid5
[root@CentOS2 /root]# echo "hello" > /raid5/testfile
[root@CentOS2 /root]# ls /raid5
lost+found  testfile  user1  user2

[root@CentOS2 /root]# dd if=/dev/zero of=/raid5/testfile bs=1024k count=500

dd: writing `/raid5/testfile': 장치에 남은 공간이 없음
378+0 records in
377+0 records out
396242944 bytes (396 MB) copied, 30.5113 s, 13.0 MB/s

[root@CentOS2 /root]# mdadm --detail --scan -v >> /etc/mdadm.conf

[root@CentOS2 /root]# mdadm --manage /dev/md5 --fail /dev/sdd1
mdadm: set /dev/sdd1 faulty in /dev/md5

[root@CentOS2 /root]# cat /proc/mdstat
Personalities : [raid0] [raid1] [raid6] [raid5] [raid4]
md5 : active raid5 sde1[3] sdd1[1](F) sdc1[0]
      414720 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/2] [U_U]

unused devices: <none>

[root@CentOS2 /root]# ls /raid5
lost+found  testfile  user1  user2

 

 

 - /dev/sdd1' 손상 상태에서 'dev/sdf1'으로 복구 실시

 

[root@CentOS2 /root]# fdisk -l /dev/sdf

Disk /dev/sdf: 213 MB, 213909504 bytes
64 heads, 32 sectors/track, 204 cylinders
Units = cylinders of 2048 * 512 = 1048576 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000875f9

   Device Boot      Start         End      Blocks   Id  System
/dev/sdf1               1         204      208880   fd  Linux raid autodetect

[root@CentOS2 /root]# mdadm --manage /dev/md5 --add /dev/sdf1
mdadm: added /dev/sdf1

[root@CentOS2 /root]# cat /proc/mdstat
Personalities : [raid0] [raid1] [raid6] [raid5] [raid4]
md5 : active raid5 sdf1[4] sde1[3] sdd1[1](F) sdc1[0]
      414720 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/2] [U_U]
      [======>..............]  recovery = 33.7% (70148/207360) finish=0.1min speed=14029K/sec

unused devices: <none>

[root@CentOS2 /root]# cat /proc/mdstat
Personalities : [raid0] [raid1] [raid6] [raid5] [raid4]
md5 : active raid5 sdf1[4] sde1[3] sdd1[1](F) sdc1[0]
      414720 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/2] [U_U]
      [============>........]  recovery = 60.8% (126720/207360) finish=0.0min speed=14080K/sec

unused devices: <none>

[root@CentOS2 /root]# cat /proc/mdstat
Personalities : [raid0] [raid1] [raid6] [raid5] [raid4]
md5 : active raid5 sdf1[4] sde1[3] sdd1[1](F) sdc1[0]
      414720 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/3] [UUU]

unused devices: <none>

 

[root@CentOS2 /root]# fdisk -l /dev/md5

Disk /dev/md5: 424 MB, 424673280 bytes
2 heads, 4 sectors/track, 103680 cylinders
Units = cylinders of 8 * 512 = 4096 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 524288 bytes / 1048576 bytes
Disk identifier: 0x00000000

[root@CentOS2 /root]# su - user1
[user1@CentOS2 /home/user1]$ exit
logout

 

 

 

Ex2) RAID 5 제거

 

[root@CentOS2 /root]# umount /dev/md5

 

[root@CentOS2 /root]# mdadm --stop /dev/md5
mdadm: stopped /dev/md5

 

[root@CentOS2 /root]# mdadm --zero-superblock /dev/sdc1 /dev/sdd1 /dev/sde1 /dev/sdf1

 

[root@CentOS2 /root]# mdadm --examine /dev/sdc1 /dev/sdd1 /dev/sde1 /dev/sdf1
mdadm: No md superblock detected on /dev/sdc1.
mdadm: No md superblock detected on /dev/sdd1.
mdadm: No md superblock detected on /dev/sde1.
mdadm: No md superblock detected on /dev/sdf1.

 

[root@CentOS2 /root]# ls /dev/md5
ls: cannot access /dev/md5: 그런 파일이나 디렉터리가 없습니다

 

[root@CentOS2 /root]# df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/sda1        13G  4.4G  7.3G  38% /
tmpfs           495M  500K  494M   1% /dev/shm
/dev/sda3       477M  2.3M  449M   1% /home

 

 

 

 

 4) RAID 0+1

최소 디스크 개수	4개 이상
장점	Stripe와 Mirror를 동시에 적용할 수 있다.
단점	비용이 많이 발생한다.
비고	CentOS에서는 지원하지 않기 때문에, Stripe를 구성하고 이를 Mirror로 구성해야 한다.

 

 

 

Ex1) RAID 0+1 구성

 

 - /dev/sdc1, /dev/sdd1, /dev/sde1, /dev/sdf1 RAID 타입 파티션 생성 확인

 
[root@CentOS2 /root]# fdisk -l /dev/sdc /dev/sdd /dev/sde /dev/sdf | grep -i raid
/dev/sdc1               1         204      208880   fd  Linux raid autodetect
/dev/sdd1               1         204      208880   fd  Linux raid autodetect
/dev/sde1               1         204      208880   fd  Linux raid autodetect
/dev/sdf1               1         204      208880   fd  Linux raid autodetect

 

 

 - CentOS에서는 'RAID 0+1' 레벨이 지원되지 않기 때문에, 먼저 Stripe 구성 실시

 

[root@CentOS2 /root]# mdadm --create /dev/md0 --level=0 --raid-devices=2  /dev/sdc1  /dev/sdd1
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md0 started.

[root@CentOS2 /root]# mdadm --create /dev/md1 --level=0 --raid-devices=2 /dev/sde1  /dev/sdf1
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md1 started.

 

 

 -  Mirror 구성 실시

 

[root@CentOS2 /root]# mdadm --create /dev/md2 --level=1 --raid-devices=2 /dev/md0 /dev/md1
mdadm: /dev/md0 appears to contain an ext2fs file system
       size=414720K  mtime=Tue Feb 23 13:49:04 2016
mdadm: Note: this array has metadata at the start and
    may not be suitable as a boot device.  If you plan to
    store '/boot' on this device please ensure that
    your boot-loader understands md/v1.x metadata, or use
    --metadata=0.90
mdadm: /dev/md1 appears to contain an ext2fs file system
       size=414720K  mtime=Tue Feb 23 13:49:04 2016
Continue creating array? y
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md2 started.

 

[root@CentOS2 /root]# ls /dev/md0
/dev/md0

[root@CentOS2 /root]# ls /dev/md1
/dev/md1

[root@CentOS2 /root]# ls /dev/md2
/dev/md2

[root@CentOS2 /root]# mdadm --detail --scan -v
ARRAY /dev/md0 level=raid0 num-devices=2 metadata=1.2 name=CentOS2:0 UUID=20576727:16c13b0e:946c3812:25fab12d
   devices=/dev/sdc1,/dev/sdd1
ARRAY /dev/md1 level=raid0 num-devices=2 metadata=1.2 name=CentOS2:1 UUID=1a11ffe9:4cbb5a2a:e3f645a8:220a4f4c
   devices=/dev/sde1,/dev/sdf1
ARRAY /dev/md2 level=raid1 num-devices=2 metadata=1.2 name=CentOS2:2 UUID=e67dc48f:eb0410e4:d24d484e:74e329fb
   devices=/dev/md0,/dev/md1

[root@CentOS2 /root]# cat /proc/mdstat
Personalities : [raid0] [raid1] [raid6] [raid5] [raid4]
md2 : active raid1 md1[1] md0[0]
      414400 blocks super 1.2 [2/2] [UU]

md1 : active raid0 sdf1[1] sde1[0]
      414720 blocks super 1.2 512k chunks

md0 : active raid0 sdd1[1] sdc1[0]
      414720 blocks super 1.2 512k chunks

unused devices: <none>

 

 

 - CentOS 6.x에서는 재부팅하면 RAID 볼륨 장치 번호가 변경된다. 변경되는 것을 방지하는 방법은 다음과 같다.

 
[root@CentOS2 /root]# mdadm --detail --scan -v 1> /etc/mdadm.conf    (RAID 설정 정보를 'mdadm.conf'에 저장)
[root@CentOS2 /root]# cat /etc/mdadm.conf
ARRAY /dev/md0 level=raid0 num-devices=2 metadata=1.2 name=CentOS2:0 UUID=20576727:16c13b0e:946c3812:25fab12d
   devices=/dev/sdc1,/dev/sdd1
ARRAY /dev/md1 level=raid0 num-devices=2 metadata=1.2 name=CentOS2:1 UUID=1a11ffe9:4cbb5a2a:e3f645a8:220a4f4c
   devices=/dev/sde1,/dev/sdf1
ARRAY /dev/md2 level=raid1 num-devices=2 metadata=1.2 name=CentOS2:2 UUID=e67dc48f:eb0410e4:d24d484e:74e329fb
   devices=/dev/md0,/dev/md1

 

 - 파일 시스템 생성 및 마운트 실시

[root@CentOS2 /root]# mkfs.ext4 /dev/md2 > /dev/null
mke2fs 1.41.12 (17-May-2010)

[root@CentOS2 /root]# mkdir /raid01
[root@CentOS2 /root]# mount /dev/md2 /raid01

[root@CentOS2 /root]# df -h /raid01
Filesystem      Size  Used Avail Use% Mounted on
/dev/md2        384M  2.3M  362M   1% /raid01

 

 Ex2) RAID 0+1 제거

 

[root@CentOS2 /root]# umount /dev/md2

 

[root@CentOS2 /root]# mdadm --stop /dev/md2
mdadm: stopped /dev/md2

 

[root@CentOS2 /root]# mdadm --stop /dev/md1
mdadm: stopped /dev/md1

 

[root@CentOS2 /root]# mdadm --stop /dev/md0
mdadm: stopped /dev/md0

 

[root@CentOS2 /root]# mdadm --zero-superblock /dev/sdc1 /dev/sdd1 /dev/sde1 /dev/sdf1

 

[root@CentOS2 /root]# mdadm --examine /dev/sdc1 /dev/sdd1 /dev/sde1 /dev/sdf1
mdadm: No md superblock detected on /dev/sdc1.
mdadm: No md superblock detected on /dev/sdd1.
mdadm: No md superblock detected on /dev/sde1.
mdadm: No md superblock detected on /dev/sdf1.

 

[root@CentOS2 /root]# ls /dev/md2
ls: cannot access /dev/md2: 그런 파일이나 디렉터리가 없습니다

 

[root@CentOS2 /root]# ls /dev/md1
ls: cannot access /dev/md1: 그런 파일이나 디렉터리가 없습니다

 

[root@CentOS2 /root]# ls /dev/md0
ls: cannot access /dev/md0: 그런 파일이나 디렉터리가 없습니다

 

[root@CentOS2 /root]# df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/sda1        13G  4.4G  7.3G  38% /
tmpfs           495M  500K  494M   1% /dev/shm
/dev/sda3       477M  2.3M  449M   1% /home

 

 

 

 

 5) RAID 1+0

최소 디스크 개수	4개 이상
장점	Stripe와 Mirror를 동시에 적용할 수 있다.
단점	비용이 많이 발생한다.
비고	RAID 0+1 보다 효율적이다.

 

 

Ex1) RAID 1+0 구성

 

 - /dev/sdc1, /dev/sdd1, /dev/sde1 RAID 타입 파티션 생성 확인

 
[root@CentOS2 /root]# fdisk -l /dev/sdc /dev/sdd /dev/sde /dev/sdf | grep -i raid
/dev/sdc1               1         204      208880   fd  Linux raid autodetect
/dev/sdd1               1         204      208880   fd  Linux raid autodetect
/dev/sde1               1         204      208880   fd  Linux raid autodetect
/dev/sdf1               1         204      208880   fd  Linux raid autodetect

 

 

 -  'mdadm' 명령어를 이용하여 RAID 1+0 구성 실시

[root@CentOS2 /root]# mdadm --create /dev/md10 --level=10 --raid-devices=4 /dev/sdc1 /dev/sdd1 /dev/sde1 /dev/sdf1
mdadm: /dev/sdc1 appears to contain an ext2fs file system
       size=103408K  mtime=Fri Feb 19 12:01:57 2016
mdadm: /dev/sdd1 appears to contain an ext2fs file system
       size=103408K  mtime=Fri Feb 19 10:15:46 2016
Continue creating array? y
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md10 started.

[root@CentOS2 /root]# ls /dev/md10
/dev/md10

[root@CentOS2 /root]# fdisk -l /dev/md10

Disk /dev/md10: 424 MB, 424673280 bytes
2 heads, 4 sectors/track, 103680 cylinders
Units = cylinders of 8 * 512 = 4096 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 524288 bytes / 1048576 bytes
Disk identifier: 0x00000000

[root@CentOS2 /root]# mdadm --detail --scan -v
ARRAY /dev/md10 level=raid10 num-devices=4 metadata=1.2 name=CentOS2:10 UUID=4b9dd62e:d750e756:98da4eaa:1c841ea6
   devices=/dev/sdc1,/dev/sdd1,/dev/sde1,/dev/sdf1

[root@CentOS2 /root]# cat /proc/mdstat
Personalities : [raid10]
md10 : active raid10 sdf1[3] sde1[2] sdd1[1] sdc1[0]
      414720 blocks super 1.2 512K chunks 2 near-copies [4/4] [UUUU]

unused devices: <none>

 

 

 - CentOS 6.x에서는 재부팅하면 RAID 볼륨 장치 번호가 변경된다. 변경되는 것을 방지하는 방법은 다음과 같다.

 
[root@CentOS2 /root]# mdadm --detail --scan -v 1> /etc/mdadm.conf    (RAID 설정 정보를 'mdadm.conf'에 저장)
[root@CentOS2 /root]# cat /etc/mdadm.conf
ARRAY /dev/md10 level=raid10 num-devices=4 metadata=1.2 name=CentOS2:10 UUID=4b9dd62e:d750e756:98da4eaa:1c841ea6
   devices=/dev/sdc1,/dev/sdd1,/dev/sde1,/dev/sdf1

 

 - 파일 시스템 생성 및 마운트 실시

[root@CentOS2 /root]# mkfs.ext4 /dev/md10 1> /dev/null
mke2fs 1.41.12 (17-May-2010)

[root@CentOS2 /root]# mkdir /raid10
[root@CentOS2 /root]# mount /dev/md10 /raid10

[root@CentOS2 /root]# df -h /raid10
Filesystem      Size  Used Avail Use% Mounted on
/dev/md10       385M  2.3M  362M   1% /raid10

 

Ex2) RAID 1+0 제거

[root@CentOS2 /root]# umount /dev/md10

[root@CentOS2 /root]# mdadm --stop /dev/md10
mdadm: stopped /dev/md10

[root@CentOS2 /root]# mdadm --zero-superblock /dev/sdc1 /dev/sdd1 /dev/sde1 /dev/sdf1

[root@CentOS2 /root]# mdadm --examine /dev/sdc1 /dev/sdd1 /dev/sde1 /dev/sdf1
mdadm: No md superblock detected on /dev/sdc1.
mdadm: No md superblock detected on /dev/sdd1.
mdadm: No md superblock detected on /dev/sde1.
mdadm: No md superblock detected on /dev/sdf1.

[root@CentOS2 /root]#  ls /dev/md10
/dev/md10

[root@CentOS2 /root]# df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/sda1        13G  4.4G  7.3G  38% /
tmpfs           495M   72K  495M   1% /dev/shm
/dev/sda3       477M  2.3M  449M   1% /home

 

 

 

 

 

 

 - 설정 초기화

 

[root@CentOS2 /root]# fdisk /dev/sdc

WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
         switch off the mode (command 'c') and change display units to
         sectors (command 'u').

 

Command (m for help): d
Selected partition 1

 

Command (m for help): w
The partition table has been altered!

 

Calling ioctl() to re-read partition table.
Syncing disks.

[root@CentOS2 /root]# fdisk /dev/sdd

WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
         switch off the mode (command 'c') and change display units to
         sectors (command 'u').

 

Command (m for help): d
Selected partition 1

Command (m for help): w
The partition table has been altered!

 

Calling ioctl() to re-read partition table.
Syncing disks.

[root@CentOS2 /root]# fdisk /dev/sde

WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
         switch off the mode (command 'c') and change display units to
         sectors (command 'u').

 

Command (m for help): d
Selected partition 1

 

Command (m for help): w
The partition table has been altered!

 

Calling ioctl() to re-read partition table.
Syncing disks.

[root@CentOS2 /root]# fdisk /dev/sdf

WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
         switch off the mode (command 'c') and change display units to
         sectors (command 'u').

 

Command (m for help): d
Selected partition 1

 

Command (m for help): w
The partition table has been altered!

 

Calling ioctl() to re-read partition table.
Syncing disks.

[root@CentOS2 /root]# fdisk /dev/sdg

WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
         switch off the mode (command 'c') and change display units to
         sectors (command 'u').

 

Command (m for help): d
Selected partition 1

 

Command (m for help): w
The partition table has been altered!

 

Calling ioctl() to re-read partition table.
Syncing disks.