Configuring clustered Samba

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Revision as of 23:27, 27 May 2007 by Sahlberg (talk | contribs) (add description for public_addresses.txt)

Setting up a simple CTDB Samba cluster

As of April 2007 you can setup a simple Samba3 or Samba4 CTDB cluster, running either on loopback (with simulated nodes) or on a real cluster with TCP. This page will tell you how to get started.

Clustering Model

The setup instructions on this page are modelled on setting up a cluster of N nodes that function in nearly all respects as a single multi-homed node. So the cluster will export N IP interfaces, each of which is equivalent (same shares) and which offers coherent CIFS file access across all nodes.

Getting the code

You need two source trees, one is a copy of Samba3 with clustering patches, and the other is the ctdb code itself. Both source trees are stored in bzr repositories. See for more information on bzr.

The fastest way to checkout an initial copy of the Samba3 tree with clustering patches is:

  rsync -avz .

To update this tree when improvements are made in the upstream code do this:

   cd samba_3_0_ctdb
   bzr merge

If you don't have bzr and can't easily install it, then you can instead use the following command to update your tree to the latest version:

   cd samba_3_0_ctdb
   rsync -avz .

Volker Lendecke maintains his own tree that sometimes has later changes in it. To merge from Volkers tree use this command:

   bzr merge

Generally the two trees will only be a day or so apart, but Samba/ctdb is undergoing fast development at the moment, so one day can include quite a few changes.

To get an initial checkout of the ctdb code do this:

  rsync -avz .

To update this tree when improvements are made in the upstream code do this:

   cd ctdb
   bzr merge

If you don't have bzr and can't easily install it, then you can instead use the following command to update your tree to the latest version:

   cd ctdb
   rsync -avz .

Building the Samba3 tree

To build a copy of Samba3 with clustering and ctdb support you should do this:

   cd samba_3_0_ctdb/source
   ./configure --prefix=/gpfs0/samba/prefix --with-ctdb=/usr/src/ctdb --with-cluster-support --enable-pie=no
   make proto

You should replace the /gpfs0/samba/prefix path with the cluster shared storage path you will use to install Samba. The path should to be a directory that is the same on all nodes of the cluster. If you are setting up a virtual cluster on loopback then this can be any local directory.

The /usr/src/ctdb path should be replaced with the path to the ctdb sources that you downloaded above

Building the CTDB tree

To build a copy of the CTDB code you should do this:

  cd ctdb
  ./configure --prefix=/gpfs0/samba/prefix
  make install

Installing Samba3

To install Samba3 you should do this:

 cd samba_3_0_ctdb/source
 make install

If your path points to another version of Samba, it is recommended that you reset your path to point to the bin/ and sbin/ directories of this newer Samba installation (e.g. /gpfs0/samba/prefix/bin and /gpfs0/samba/prefix/sbin). Then you need to configure an appropriate smb.conf. There is a very simple example in samba_3_0_ctdb/examples/ctdb. You need to put this smb.conf in the lib/ subdirectory of the prefix you chose above.

Next you need to initialise the Samba password database, e.g.

 smbpasswd -a root

or if you have not reset your path to point to this newer version of Samba:

 /gpfs0/samba/prefix/bin/smbpasswd -a root

Samba with clustering must use the tdbsam or ldap SAM passdb backends (it must not use the default smbpasswd backend). The rest of the configuration of Samba is exactly as it is done on a normal system. See the docs on for details.

Cluster Configuration

The two main cluster configuration file are cluster_nodes.txt and public_addresses.txt in your Samba configuration directory (the lib/ subdirectory of your Samba installation prefix).


This file needs to be created and should contain a list of the private IP addresses that the CTDB daemons will use in your cluster. This should be a private non-routable subnet which is only used for CTDB traffic.

Example :


This file contains a list (one for each node) of public cluster addresses. these are the addresses that the SMBD daemons will bind to. During failover of nodes, the CTDB daemons will take over the public address of a failed node to ensure that all public addresses are always available to clients.


These are the IP addresses that you should configure in DNS for the name of the clustered samba server and are the addresses that cifs clients will connect to.

Starting the cluster

There is an example startup script in samba_3_0_ctdb/examples/ctdb/ This script will read your cluster_nodes.txt and create smb.conf files for each node, and start smbd and ctdbd on each node of the cluster.

Loopback Setup

For testing purposes you can setup a Samba/CTDB cluster on a single computer using loopback networking. To set this up you need to do this:

- use ifconfig to create IP aliases for your loopback device for each virtual node
- put the list of aliased IP addresses in cluster_nodes.txt

For example in order to create loopback devices 2 through 4 (lookpback device 1 already exists on most systems), you could do this:

 for i in `seq 2 4`; do
   ifconfig lo:$i 127.0.0.$i

then to configure these you would create a cluster_nodes.txt with the lines:

Then start the cluster as above. For the system to start you also need an onnode script in your path. For this simple example of running a simulated cluster on a single computer the onnode.loop example script can be renamed to onnode in order to create the necessary script. The user rarely needs to directly invoke this script but it is used by the cluster startup script to remotely execute commands on other cluster nodes. There is a second example onnode script, onnode.ssh, which is not needed for this example (but which could be renamed to onnode, instead of using onnode.local, when using a multi-computer cluster). The last line of onnode.ssh, which contains the sample command for starting ssh could be changed (e.g. for certain Kerberized ssh configurations) when the cluster is run over multiple computers.

Testing your cluster

Once your cluster is up and running, you may wish to know how to test that it is functioning correctly. The following tests may help with that

Using ctdb_control

The ctdb package comes with a utility called ctdb_control that can be used to look at the behaviour of the ctdb protocol. If you run it with no options it will provide some terse usage information. The most commonly used commands are:

- ctdb_control ping
- ctdb_control status all

Using smbcontrol

You can check for connectivity to the smbd daemons on each node using smbcontrol

- smbcontrol smbd ping

Using Samba4 smbtorture

The Samba4 version of smbtorture has several tests that can be used to benchmark a CIFS cluster. You can download Samba4 like this:

 svn co svn://

Then configure and compile it as usual. The particular tests that are helpful for cluster benchmarking are the RAW-BENCH-OPEN, RAW-BENCH-LOCK and BENCH-NBENCH tests. These tests take a unclist that allows you to spread the workload out over more than one node. For example:

 smbtorture //localhost/data -Uuser%password  RAW-BENCH-LOCK --unclist=unclist.txt --num-progs=32 -t60

A suitable unclist.txt is generated in your $PREFIX/lib directory when you run

For NBENCH testing you need a client.txt file. A suitable file can be found in the dbench distribution at