Setting Up Network RAID1 With DRBD On Debian Squeeze - Page 2
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4 Install And Configure DRBD
server1/server2:
Now install DRBD on both nodes as follows:
apt-get install drbd8-utils
Load the DRBD kernel module:
modprobe drbd
To check if it is loaded, run:
lsmod | grep drbd
Output should be similar to this one:
root@server1:~# lsmod | grep drbd
drbd 193312 0
lru_cache 5042 1 drbd
cn 4563 1 drbd
root@server1:~#
Now we back up the original /etc/drbd.conf file and create a new one on both nodes as follows:
cp /etc/drbd.conf /etc/drbd.conf_orig
cat /dev/null > /etc/drbd.conf
vi /etc/drbd.conf
global { usage-count no; }
common { syncer { rate 100M; } }
resource r0 {
protocol C;
startup {
wfc-timeout 15;
degr-wfc-timeout 60;
}
net {
cram-hmac-alg sha1;
shared-secret "secret";
}
on server1.example.com {
device /dev/drbd0;
disk /dev/sdb1;
address 192.168.0.100:7788;
meta-disk internal;
}
on server2.example.com {
device /dev/drbd0;
disk /dev/sdb1;
address 192.168.0.101:7788;
meta-disk internal;
}
}
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Make sure you use the correct node names in the file (instead of server1.example.com and server2.example.com) - please make sure you use the node names that the command
uname -n
shows on both nodes. Also make sure you fill in the correct IP addresses in the address lines and the correct disk in the disk lines (if you don't use /dev/sdb1).
Now we initialize the meta data storage. On both nodes run:
drbdadm create-md r0
root@server1:~# drbdadm create-md r0
Writing meta data...
initializing activity log
NOT initialized bitmap
New drbd meta data block successfully created.
root@server1:~#
Then start DRBD on both nodes:
/etc/init.d/drbd start
root@server1:~# /etc/init.d/drbd start
Starting DRBD resources:[ d(r0) s(r0) n(r0) ]....
root@server1:~#
The next step has to be carried out on server1 only:
server1:
Now make server1 the primary node:
drbdadm -- --overwrite-data-of-peer primary all
Afterwards, data will start to synchronize between server1 and server2.
server2:
Take a look at
cat /proc/drbd
to see the synchronization progress:
root@server2:~# cat /proc/drbd
version: 8.3.7 (api:88/proto:86-91)
srcversion: EE47D8BF18AC166BE219757
0: cs:SyncTarget ro:Secondary/Primary ds:Inconsistent/UpToDate C r----
ns:0 nr:15790400 dw:15790144 dr:0 al:0 bm:963 lo:9 pe:29622 ua:8 ap:0 ep:1 wo:b oos:15664096
[=========>..........] sync'ed: 50.3% (15296/30716)M
finish: 0:02:44 speed: 95,212 (85,352) K/sec
root@server2:~#
(You can run
watch cat /proc/drbd
to get an ongoing output of the process. To leave watch, press CTRL+C.)
Wait until the synchronization has finished - output should be as follows:
root@server2:~# cat /proc/drbd
version: 8.3.7 (api:88/proto:86-91)
srcversion: EE47D8BF18AC166BE219757
0: cs:Connected ro:Secondary/Primary ds:UpToDate/UpToDate C r----
ns:0 nr:31454240 dw:31454240 dr:0 al:0 bm:1920 lo:0 pe:0 ua:0 ap:0 ep:1 wo:b oos:0
root@server2:~#
The snippet ro:Secondary/Primary tells you that this node is the secondary node.
server1:
On server1, the output of
cat /proc/drbd
is as follows (after the synchronization has finished):
root@server1:~# cat /proc/drbd
version: 8.3.7 (api:88/proto:86-91)
srcversion: EE47D8BF18AC166BE219757
0: cs:Connected ro:Primary/Secondary ds:UpToDate/UpToDate C r----
ns:31454240 nr:0 dw:0 dr:31454440 al:0 bm:1920 lo:0 pe:0 ua:0 ap:0 ep:1 wo:b oos:0
root@server1:~#
The snippet Primary/Secondary tells you that this is the primary node.
Now that we have our new network RAID1 block device /dev/drbd0 (which consists of /dev/sdb1 from server1 and server2), let's create an ext3 filesystem on it and mount it to the /data directory. This has to be done only on server1!
mkfs.ext3 /dev/drbd0
mkdir /data
mount /dev/drbd0 /data
Afterwards you should see /dev/drbd0 in the outputs of...
mount
root@server1:~# mount
/dev/sda1 on / type ext3 (rw,errors=remount-ro)
tmpfs on /lib/init/rw type tmpfs (rw,nosuid,mode=0755)
proc on /proc type proc (rw,noexec,nosuid,nodev)
sysfs on /sys type sysfs (rw,noexec,nosuid,nodev)
udev on /dev type tmpfs (rw,mode=0755)
tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev)
devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=620)
/dev/drbd0 on /data type ext3 (rw)
root@server1:~#
... and:
df -h
root@server1:~# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda1 29G 775M 27G 3% /
tmpfs 249M 0 249M 0% /lib/init/rw
udev 244M 112K 244M 1% /dev
tmpfs 249M 0 249M 0% /dev/shm
/dev/drbd0 30G 173M 28G 1% /data
root@server1:~#
5 Test
server1:
Now let's create some files or directories in the /data directory and check whether they get replicated to server2.
touch /data/test1.txt
touch /data/test2.txt
ls -l /data/
root@server1:~# ls -l /data/
total 16
drwx------ 2 root root 16384 Aug 8 12:45 lost+found
-rw-r--r-- 1 root root 0 Aug 8 12:48 test1.txt
-rw-r--r-- 1 root root 0 Aug 8 12:48 test2.txt
root@server1:~#
Now let's unmount the /data directory on server1:
umount /data
Then assign the secondary role to server1:
drbdadm secondary r0
Now we go to server2, make it the primary node and check if we can see the files/directories we created on server1 in the /data directory on server2.
server2:
First we assign the primary role to server2:
drbdadm primary r0
Check the output of
cat /proc/drbd
... and you should see that server2 is the primary node now:
root@server2:~# cat /proc/drbd
version: 8.3.7 (api:88/proto:86-91)
srcversion: EE47D8BF18AC166BE219757
0: cs:Connected ro:Primary/Secondary ds:UpToDate/UpToDate C r----
ns:4 nr:32083300 dw:32083304 dr:325 al:1 bm:1920 lo:0 pe:0 ua:0 ap:0 ep:1 wo:b oos:0
root@server2:~#
Next we create the /data directory and mount /dev/drbd0 to it:
mkdir /data
mount /dev/drbd0 /data
Let's check the contents of the /data directory:
ls -l /data/
If everything went fine, it should contain the files/directories that we created on server1:
root@server2:~# ls -l /data/
total 16
drwx------ 2 root root 16384 Aug 8 12:45 lost+found
-rw-r--r-- 1 root root 0 Aug 8 12:48 test1.txt
-rw-r--r-- 1 root root 0 Aug 8 12:48 test2.txt
root@server2:~#
server1:
Now that we have switched roles, the output of
cat /proc/drbd
on server1 should show you that server1 has the secondary role:
root@server1:~# cat /proc/drbd
version: 8.3.7 (api:88/proto:86-91)
srcversion: EE47D8BF18AC166BE219757
0: cs:Connected ro:Secondary/Primary ds:UpToDate/UpToDate C r----
ns:32083300 nr:4 dw:629064 dr:31454797 al:529 bm:2044 lo:0 pe:0 ua:0 ap:0 ep:1 wo:b oos:0
root@server1:~#
6 Links
- DRBD: http://www.drbd.org/
- Debian: http://www.debian.org/
