As I’ve been written on my previous post about Maildir Replication using ChironFS in postfix, I will explain step by step it can also be done by using drbd and ocfs2.
Compiling & Installing
note: if your Linux distribution is shipped with a kernel older than 2.6.33 you have to install a kernel module package and packages for the user land code. If your distribution contains a Linux-2.6.33 kernel or newer you only need to install the user land code.
In my case i have my linux distribution older than 2.6.33, so i will also compile drbd kernel module.
Download drbd source and create Binary RPMS packages
$ wget http://oss.linbit.com/drbd/8.3/drbd-8.3.10.tar.gz $ tar xvzf drbd-8.3.10.tar.gz $ cd drbd-8.3.10 $ ./configure --enable-spec --with-km $ cp ../drbd*.tar.gz `rpm -E %_sourcedir` $ rpmbuild -bb drbd.spec $ rpmbuild -bb drbd-km.spec $ sudo rpm -ivh /path/to/RPMS/drbd-*
I’ll be using loop files for this setup since I don’t have access to raw partitions. but if you have raw block device available you can subtitute this part:
resource r0 {
meta-disk internal;
device /dev/drbd0;
disk /dev/loop0;
Into:
resource r0 {
meta-disk internal;
device /dev/drbd0;
disk /dev/sdxx;
sdxx can be sda1, sdb1 sdb2 or what ever your raw disk device called
# dd if=/dev/zero of=/drbd-postfix.img bs=1M count=5000 # losetup /dev/loop0 /drbd-postfix.img
Place this DRBD resource file in /etc/drbd.d/r0.res. Be sure to adjust the server names and IP addresses for your servers.
resource r0 {
meta-disk internal;
device /dev/drbd0;
disk /dev/loop0;
syncer { rate 1000M; }
net {
allow-two-primaries;
after-sb-0pri discard-zero-changes;
after-sb-1pri discard-secondary;
after-sb-2pri disconnect;
}
startup { become-primary-on both; }
on postfix1 { address 192.168.200.18:7789; }
on postfix2 { address 192.168.200.114:7789; }
}