Jun 192011
 

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; }
}

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Jun 142011
 

In this tutorial I will describe how to set up postfix and maildir which can automatically replicate email when email is delivered. We will not touch the postfix configuration at all. we will manipulate maildir directory behavior using ChironFS, instead.

what is ChironFS?

This the Chiron Filesystem. It is a Fuse based filesystem. It’s main purpose is to guarantee filesystem availability using replication. But it isn’t a RAID implementation. RAID replicates DEVICES not FILESYSTEMS.

Things we need before installing chironfs

  • fuse
  • fuse-devel
  • fuse-libs
  • ChironFS source/binary from here

Compile ChironFS source

RPM:

$ rpmbuild --rebuild chironfs-1.0.0-1.fc8.src.rpm
$ rpm -ivh /path/to/chironfs-1.0.0-1.fc12.rpm

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