Creating a Two Node Mysql Cluster On Ubuntu With DRBD Part 2

2011-05-11 · 7 min read · Linux OpenSource Personal Thoughts Ubuntu VMware

This blog is a follow on from a blog post I wrote ages ago and have eventually got round to finishing it off In this part of the process we will create the disks and setup the DRBD devices First we need to connect to the Virtual Machines from a terminal session as it makes life much easier and quicker when you connect remotely. You will need to make sure that your servers have static IP addresses. For this document I will be using the following IP addresses for my servers.

1drbdnode1 = 172.16.71.139
2drbdnode2 = 172.16.71.140
3drbdmstr = 172.16.71.141 (clustered IP address)
4Subnet Mask = 255.255.255.0
5Gateway = 172.16.71.1
6DNS Servers = 8.8.8.8 and 4.4.4.4

So to set the IP address as fixed you need to do the following. Connect to the console of drbdnode1 and login now we need to edit the file that contains the IP address of the network card enter the following command and press return

1sudo nano /etc/network/interfaces

enter the password for the user you are logged in as You should see the following screen

now use your arrow keys on your keyboard and move the white cursor to the section that starts with iface eth0 press Ctrl K to remove the line then add the lines below with your IP address details

1auto eth0
2iface eth0 inet static
3address 172.16.71.139
4netmask 255.255.255.0
5network 172.16.71.0
6broadcast 172.16.71.255
7gateway 172.16.71.1

It should end up looking like this

Now press Ctrl X to exit Then Y Then press Enter to save Now type in the following

1sudo /etc/init.d/networking restart

Do the same for drbdnode2 Now that we have given each server a static Ip address we can connect via ssh to the server to do the admin remotely. To do this you need to have a machine that has an ssh client installed most linux and osx clients have one already installed if you are on windows look for putty and use that. So open a terminal on your machine and the in the following

1ssh [email protected] and press enter.

You need to substitute the username you created on your server when setting it up for the word cluster in the above command. You will be prompted to accept a key for the server. Type yes and press enter. Now enter the password for the user and press enter. You should see a screen like this

Connect to both cluster nodes to make sure you are not stopped down the line to fix the problem. You are now ready to work on your cluster. First we need to create host records for the two servers type the following into your terminal session

1sudo nano /etc/hosts

and add a record for each server it should look something like this

Save the file as before and do the same for node2 but swap the names and ipadresses Now we need to install a few packages that will allow us to use drbd in the terminal on drbdnode1 type

1apt-get install heartbeat drbd8-utils

and press enter you should have a screen like this

Press Y and then Enter to install the software. Do this on drbdnode2 as well Now we need to create the partitions that we will use for the drbd cluster to find out which disk we will be using run the command

1sudo fdisk -l

to see which disks have not been partitioned your screen should look like this

As you can see at the end is the disk /dev/sdb does not have a partition table look for the line “ Disk /dev/sdb doesn't contain a valid partition table “ to create a partition table we need to run the following commands

1sudo fdisk /dev/sdb
2n (to create a new partition)
3p (to select a primary partition)
41 (for the first partition)
5Enter (to select the start cylinder)
6and enter (to select the end cylinder)
7w (to write the changes)

the screen should look like this

Do this on both servers once this is complete we now need to edit the drbd configuration files to set up our clustered filesystem. In your terminal on drbdnode1 enter the command

1sudo nano /etc/drbd.d/clusterdisk.res

Enter the password for your user and edit the file Copy and paste the following code into your terminal screen and then change the details to match your server names and ip addresses

 1resource clusterdisk {
 2  # name of resources
 3  protocol C;
 4  on drbdnode1 { # first server hostname
 5  device /dev/drbd0; # Name of DRBD device
 6  disk /dev/sdb1; # Partition to use, which was created using fdisk
 7  address 172.16.71.139:7788; # IP addres and port number used by drbd
 8  meta-disk internal; # where to store metadata meta-data
 9}
10
11on drbdnode2
12{
13  # second server hostname
14  device /dev/drbd0;
15  disk /dev/sdb1;
16  address 172.16.71.140:7788;
17  meta-disk internal;
18}
19disk {
20  on-io-error detach;
21}
22net {
23  max-buffers 2048;
24  ko-count 4;
25}
26syncer {
27  rate 10M;
28  al-extents 257;
29}
30startup {
31  wfc-timeout 0;
32  degr-wfc-timeout 120; # 2 minutos.
33}
34
35}

The screen should look similar to this

ctrl x (to exit) y (to save the changed file) enter (to overwrite the file) Now we need to create the DRBD resource enter the following command into your terminal session

1sudo drbdadm create-md clusterdisk

After running this command you should see a screen similar to this

On drbdnode1 enter the following command

1drbdadm -- --overwrite-data-of-peer primary all

this will activate it as the primary drbd node to see if this has worked you can run the following command

1sudo drbdadm status

the result should look like this on drbdnode1

and like this on drbdnode2

you will see that drbdnode1 has a status of cs="SyncSource" and drbdnode2 has a status of cs="SyncTarget" this tells you what role they are playing in the cluster at the end of this line you will see a status resynced_percent="3.8" this tells you how much the drbd disk has synced. Once the sync is complete connect to drbdnode1 and run the following command

1sudo mkfs.ext4 /dev/drbd0

this will create an ext4 partition on the drbd file system. Which will sync across to drbdnode2

Configuring heartbeat resource

Now we need to setup the Mysql resource in the heartbeat configuration firstly we need to create a file called authkeys. The file should be created in /etc/ha.d directory. You can do this with the following command

1nano /etc/ha.d/authkeys

in this file you need to add the following text.

1auth 3
2
33 md5 [SECRETWORD]

Replace [SECRETWORD] with a key you have generated. This file needs to be on both servers in the /etc/ha.d directory. After you have created the file you need to change the permissions on the file to make it more secure. This can be done with the following command

1chmod 600 /etc/ha.d/authkeys

do this on both servers Now we need to create the /etc/ha.d/ha.cf file to store the cluster config. You can do this with the following command

1nano /etc/ha.d/ha.cf

copy and paste this code into the file

 1logfile /var/log/ha-log
 2
 3keepalive 2
 4
 5deadtime 30
 6
 7udpport 695
 8
 9bcast eth0
10auto\_failback off
11stonith\_host drbdnode1 meatware drbdnode2
12stonith\_host drbdnode2 meatware drbdnode1
13node drbdnode1 drbdnode2

do the same for both servers next is the haresources file. Create the file here

1nano /etc/ha.d/haresources

paste this code in there

1dhcp-1 IPaddr::172.16.71.141 /24/eth0 drbddisk::clusterdisk Filesystem::/dev/drbd0::/var/lib/mysql::ext4 mysql

Your cluster is now ready to role. All you now need to do is test the cluster which I will tell you how to do in a future blog post Let me know how you get on

Creating a Two Node Mysql Cluster On Ubuntu With DRBD Part 2

Configuring heartbeat resource

Posts in this series