This section describes best practices for the following subjects:

This page is a list of Best Practices for when setting up and installing Xpand. See Xpand Installation Guide Bare OS Instructions to complete the initial installation and general configuration instructions. 

Network Configuration

IP addressing and Hostnames

When setting up a new cluster it is best to maintain consistent ordering and numbering with IP address, hostnames, and node numbers.

For example:

Currently, to achieve this, you have to add nodes one at a time to the cluster using either ALTER CLUSTER Syntax - Flex Up or the Flex Up page on the XpandGUI. Otherwise, the node number is random as the numbers are assigned in the order that the nodes respond to the addition request.

This is only relevant for on-premises installations, as you don't typically have that much control over IP address allocation in cloud/hosted environments.

Multi-homed Network Configuration

While Xpand runs fine on nodes with a single network connection, the recommended network topology is a setup with at least two ethernet connections; the front-end and back-end. The front-end ethernet is for external traffic to communicate with the cluster while the back-end ethernet should be used for internode communication only.

For more information on setting up the network, please see Network Security with Xpand.

When adding nodes to a cluster in a cloud environment such as AWS or Rackspace it is important to use the internal IP address as using the external address can cause cluster creation to fail.

Network Security

The 3 main approaches to security are as follows:

In a typical secure configuration, you will limit access to TCP Ports 80, 8080, and 22 to the network CIDR range that maps to the public IPs for your administrative clients (typically exposed through your firewall), and you will limit access to TCP Port 3306 to your administrative client CIDR range and also to the range of IPs used by your application servers (if they are outside your firewall).

For complete details on how to set up security, please see Network Security with Xpand.

Front-end Load Balancing

Xpand has been designed to take full advantage of a front-end load balancer. We recommend HAProxy. Please see Load Balancing Xpand with HAProxy for details.


NTP should be running so that the nodes' clocks do not get out of sync; otherwise, you may get inconsistent timestamps when using now() , and this also makes log analysis much more difficult. See Verify NTP is running on Xpand.

Managing Internode SSH Access

There are three methods of internode SSH access, listed here in order of administrative simplicity:

  1. Host Based Authentication. The Xpand installer will set up host based authentication if allowed. (This is Recommended.)
  2. Key Pair Authentication. For information on configuring key pair authentication, see Internode Administrative Connectivity via Ethernet.
  3. Password.

If you use password-based authentication then the CLX Command Line Tool will require a password for most commands.

For ease of use, we suggest having the same password for each node.


Databases are not typically network-bound (as compared to a file server), however, a clustered database system does rely upon low latency links between nodes.

To learn more about how network latency can affect nodes in a cluster please see Recognizing Platform Limits.

Storage Configuration



Below are some general best practices on RAID configuration for Xpand:

For more information about the various RAID level please see Wikipedia: RAID.

File System

For optimal performance use the ext4 format for your filesystem. 

Xpand will work when using an ext3 formatted volume, but it will generate warnings during startup and space allocation. Growing an ext3 device file will take longer than with other volume formats. 

You can see which format your filesystem is with the following:

shell> # df -T
Filesystem    Type   1K-blocks       Used  Available Use% Mounted on
/dev/md1      ext3    14446128    2253276   11459028  17% /
tmpfs        tmpfs    16440012     131076   16308936   1% /dev/shm
/dev/md0      ext3      253807      27521     213182  12% /boot
/dev/md3      ext4  1060589952  993662712   13052376  99% /data/clustrix
/dev/sdh1     ext3   484535504    9458888  450657416   3% /data/clustrix/log 

In the above example, we have most of the partitions running ext3 and the main /data partition running ext4.

Operating System Concerns


Below are the general operating system best practices and concerns for running the Xpand software. 


Do not configure swap. Having the database process go to swap, even on SSD, will degrade performance.