centos7(rhel7) 환경에서 DRBD 설정하기

 

환경개요

서버 대수 : 2대
구성 방식 : Master & Standby 구성
OS : centos7

Master서버
IP : 192.168.0.177
hostname : node1
drbd 사용장치 : /dev/sdb1

Standby서버
IP : 192.168.0.178
hostname : node2
drbd 사용장치 : /dev/sdb1

 

1. elrepo 저장소 등록

Import the public key:
rpm –import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org

To install ELRepo for RHEL-7, SL-7 or CentOS-7:
rpm -Uvh http://www.elrepo.org/elrepo-release-7.0-2.el7.elrepo.noarch.rpm

 

2. drbd 패키지 설치

yum install drbd84-utils kmod-drbd84

사실 yum install drbd 라고 명령어를 내리면 drbd84-utils 를 자동으로 인지하고 설치한다.

 

3. selinux 끄기

파일 : /etc/sysconfig/selinux

SELINUX=diabled

리부팅을 해도 되고 ”setenforce 0” 명령을 실행해도 됨

4. 호스트이름 설정

Master :

hostname node1

Standby :

hostname node2

 

5. /etc/hosts 파일 설정 (Master, Standby 모두 동일)

192.168.0.177 node1
192.168.0.178 node2

 

 

6. 파티션 생성

[root@node1]# fdisk /dev/sdb
Welcome to fdisk (util-linux 2.23.2).

Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.

Command (m for help): n
Partition type:
 p primary (0 primary, 0 extended, 4 free)
 e extended
Select (default p): p
Partition number (1-4, default 1): 1
First sector (2048-4194303, default 2048): 
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-4194303, default 4194303): 
Using default value 4194303
Partition 1 of type Linux and of size 2 GiB is set

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

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


[root@node1]# fdisk -l /dev/sdb

Disk /dev/sdb: 2147 MB, 2147483648 bytes, 4194304 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0xc4ea1609

Device Boot Start End Blocks Id System
/dev/sdb1 2048 4194303 2096128 83 Linux

 

7. 설정파일 생성 (Master, Standby 모두 동일)

파일위치 : /etc/drbd.d/drbddata

resource drbddata {
startup {
wfc-timeout 30;
degr-wfc-timeout 30;
}
net {
cram-hmac-alg sha1;
shared-secret sync_disk;
}
syncer {
rate 100M;
al-extents 257;
on-no-data-accessible io-error;
}
on node1 {
device /dev/drbd0;
disk /dev/sdb1;
address 192.168.0.177:7788;
meta-disk internal;
}
on node2 {
device /dev/drbd0;
disk /dev/sdb1;
address 192.168.0.178:7788;
meta-disk internal;
}
}

 

8. 메타데이터 생성 (Master, Standby 모두 동일)

drbdadm create-md drbddata

대략 이런 결과…

[root@node1]# drbdadm create-md drbddata
md_offset 2146430976
al_offset 2146398208
bm_offset 2146332672

Found ext3 filesystem
 2096028 kB data area apparently used
 2096028 kB left usable by current configuration

Even though it looks like this would place the new meta data into
unused space, you still need to confirm, as this is only a guess.

Do you want to proceed?
[need to type 'yes' to confirm] yes

initializing activity log
NOT initializing bitmap
Writing meta data...
New drbd meta data block successfully created.
success

 

9. drbd 구동

Master 서버에서 먼저 drbd를 구동후 완료될때 까지 기다리자.
구동이 완료되고 난후 /proc/drbd 를 확인하여 상태를 본다.

[root@node1]# systemctl start drbd
[root@node1]# cat /proc/drbd 
version: 8.4.6 (api:1/proto:86-101)
GIT-hash: 833d830e0152d1e457fa7856e71e11248ccf3f70 build by phil@Build64R7, 2015-04-10 05:13:52
 0: cs:WFConnection ro:Secondary/Unknown ds:Inconsistent/DUnknown C r----s
 ns:0 nr:0 dw:0 dr:0 al:0 bm:0 lo:0 pe:0 ua:0 ap:0 ep:1 wo:f oos:2096028

여기 까지 확인했다면 Standby 서버에서도 drbd를 구동한다.
구동이 완료되고 난후 다시한번 /proc/drbd 를 확인하여 상태를 본다.

[root@node1]# cat /proc/drbd
version: 8.4.6 (api:1/proto:86-101)
GIT-hash: 833d830e0152d1e457fa7856e71e11248ccf3f70 build by phil@Build64R7, 2015-04-10 05:13:52
0: cs:Connected ro:Secondary/Secondary ds:Inconsistent/Inconsistent C r-----
ns:0 nr:0 dw:0 dr:0 al:0 bm:0 lo:0 pe:0 ua:0 ap:0 ep:1 wo:f oos:2096028

[root@node2]# cat /proc/drbd
version: 8.4.6 (api:1/proto:86-101)
GIT-hash: 833d830e0152d1e457fa7856e71e11248ccf3f70 build by phil@Build64R7, 2015-04-10 05:13:52
0: cs:Connected ro:Secondary/Secondary ds:Inconsistent/Inconsistent C r-----
ns:0 nr:0 dw:0 dr:0 al:0 bm:0 lo:0 pe:0 ua:0 ap:0 ep:1 wo:f oos:2096028

 

10. Master 설정 (Master 서버에서만 실행)

[root@node1]# drbdadm primary --force drbddata
[root@node1]# cat /proc/drbd
version: 8.4.6 (api:1/proto:86-101)
GIT-hash: 833d830e0152d1e457fa7856e71e11248ccf3f70 build by phil@Build64R7, 2015-04-10 05:13:52
0: cs:SyncSource ro:Primary/Secondary ds:UpToDate/Inconsistent C r-----
ns:74224 nr:0 dw:0 dr:74952 al:0 bm:0 lo:0 pe:0 ua:0 ap:0 ep:1 wo:f oos:2021804
[>....................] sync'ed: 3.8% (2021804/2096028)K
finish: 0:01:21 speed: 24,740 (24,740) K/sec

drbdadm -- --overwrite-data-of-peer primary drbddata

 

11. 파티션 마운트

[root@node1 ~]# mkfs.ext4 /dev/drbd0
mke2fs 1.42.9 (28-Dec-2013)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
131072 inodes, 524007 blocks
26200 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=536870912
16 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912

Allocating group tables: done
Writing inode tables: done
Creating journal (8192 blocks): done
Writing superblocks and filesystem accounting information: done

[root@node1 ~]# mount /dev/drbd0 /data
[root@node1 ~]# df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/mapper/centos-root 6981632 2489436 4492196 36% /
devtmpfs 499476 0 499476 0% /dev
tmpfs 508740 0 508740 0% /dev/shm
tmpfs 508740 6708 502032 2% /run
tmpfs 508740 0 508740 0% /sys/fs/cgroup
/dev/sda1 508588 153416 355172 31% /boot
/dev/drbd0 2030316 6144 1902988 1% /data

 

12. Master 가 죽었다고 가정한뒤 Standby를 활성화

Master가 죽었음을 흉내

systemctl stop drbd

Standby에서 상태확인

[root@node2]# cat /proc/drbd
version: 8.4.6 (api:1/proto:86-101)
GIT-hash: 833d830e0152d1e457fa7856e71e11248ccf3f70 build by phil@Build64R7, 2015-04-10 05:13:52
0: cs:WFConnection ro:Secondary/Unknown ds:UpToDate/DUnknown C r-----
ns:0 nr:2211728 dw:2211728 dr:0 al:0 bm:0 lo:0 pe:0 ua:0 ap:0 ep:1 wo:f oos:0

Standby  서버를 primary 모드로 전환

[root@node2 drbd.d]# drbdadm primary drbddata
[root@node2 drbd.d]# cat /proc/drbd
version: 8.4.6 (api:1/proto:86-101)
GIT-hash: 833d830e0152d1e457fa7856e71e11248ccf3f70 build by phil@Build64R7, 2015-04-10 05:13:52
0: cs:WFConnection ro:Primary/Unknown ds:UpToDate/DUnknown C r-----
ns:0 nr:2211728 dw:2211728 dr:728 al:0 bm:0 lo:0 pe:0 ua:0 ap:0 ep:1 wo:f oos:0

13. Master 서버를 복구한뒤 다시 서비스 전환

Master 서버가 복구되었음을 가정하고
drbd 서비스를 올림

[root@node1 ~]# systemctl start drbd
[root@node1 ~]# cat /proc/drbd
version: 8.4.6 (api:1/proto:86-101)
GIT-hash: 833d830e0152d1e457fa7856e71e11248ccf3f70 build by phil@Build64R7, 2015-04-10 05:13:52
0: cs:Connected ro:Secondary/Primary ds:UpToDate/UpToDate C r-----
ns:0 nr:0 dw:0 dr:0 al:0 bm:0 lo:0 pe:0 ua:0 ap:0 ep:1 wo:f oos:0

/proc/drbd를 확인해보면 본래의 Master서버가 secondary 상태임을 알 수 있다.

Standby 서버를 secondary 모드로 전환
(현재 Standby서버가 primary 모드인데, 구성상 primary 상태의 서버가 두대일 수 없으므로 secondary 모드로 전환하는 것이다)

[root@node2]# drbdadm secondary drbddata
[root@node2]# cat /proc/drbd
version: 8.4.6 (api:1/proto:86-101)
GIT-hash: 833d830e0152d1e457fa7856e71e11248ccf3f70 build by phil@Build64R7, 2015-04-10 05:13:52
0: cs:Connected ro:Secondary/Secondary ds:UpToDate/UpToDate C r-----
ns:73108 nr:2211728 dw:2284836 dr:1898 al:6 bm:0 lo:0 pe:0 ua:0 ap:0 ep:1 wo:f oos:0

Master 서버를 primary 모드로 전환

[root@node1 ~]# drbdadm primary drbddata
[root@node1 ~]# cat /proc/drbd
version: 8.4.6 (api:1/proto:86-101)
GIT-hash: 833d830e0152d1e457fa7856e71e11248ccf3f70 build by phil@Build64R7, 2015-04-10 05:13:52
0: cs:Connected ro:Primary/Secondary ds:UpToDate/UpToDate C r-----
ns:0 nr:73108 dw:73108 dr:728 al:0 bm:0 lo:0 pe:0 ua:0 ap:0 ep:1 wo:f oos:0

이것으로 복구 작업이 완료되었다.