Use the following configuration settings in the node or cluster configuration file to implement the Swarm multi-server feature:

Chassis Processes Setting

The chassis.processes setting allows specifying the number of independent Swarm server processes to be started in a physical chassis.

For best results, use n-1 processes for a chassis with n CPU cores, as too many Swarm server processes impairs performance. The setting value must be an integer greater than 1.

For example, to implement two server processes within a single physical chassis, add the following entry to the node or cluster configuration file:

chassis.processes = 2

Make sure that the number of IP addresses specified by the network.ipAddress setting matches the number of processors specified by the chassis.processes setting. For example, if you set chassis.processes = 3, make sure you specify three IP addresses.

Network Setup Settings

When you implement a multi-server Swarm storage cluster, you must assign each node a static IP address because DHCP cannot be implemented in multi-server mode. When you enable the multi-server mode, the network.ipAddress setting syntax is extended by appending the IP address for each process in a list, separated by a space.

The number of IP addresses must equal the number of server processes specified in the chassis.processes setting. The network.netmask, default network.gateway, and all other network settings are shared for all processes. They need to be specified once, as in a single-process implementation.

For example, for a chassis with two processes, you can use the following node or cluster configuration file entries:

chassis.processes = 2 
network.ipAddress = 192.10.11.200 192.10.11.201 
network.netmask = 255.255.0.0 
network.gateway = 192.10.1.1

Using the disk.volumes Setting

When you configure a multi-server chassis, the disk.volumes setting in the node or cluster configuration file specifies the volume or volumes Swarm can use for cluster storage. The recommended setting (disk.volumes = all) causes Swarm to use all volumes greater than the configured disk.minGB (64 GB by default). If you are booting Swarm from a USB flash drive, that drive is automatically excluded from the volume list.

The disk.volumes = all setting causes all volumes in a chassis to be distributed evenly among the number of Swarm processes as defined by the chassis.processes setting. This distribution occurs automatically at boot time and adapts to any changes in the number of drives or processes from the previous boot. This allows Swarm to redistribute volumes among Swarm processes as needed each reboot.

Using the node.subcluster Setting

When using the multi-server mode, all nodes in a chassis are assigned a subcluster name, either by the administrator or automatically at boot time. You can optionally set the subcluster name using the node.subcluster setting.

If the node.subcluster setting is blank or not set, an automatic value is assigned when using multi-server mode in Swarm. The automatic subcluster assignment sets the subcluster name to the value of the first IP address for the chassis. The automatic assignment of subcluster creates a different subcluster each multi-server chassis.

Set node.subcluster = to a value up to 16 characters the subcluster is named. Special characters such as quotation marks and dashes cannot be used. Enter the following in the node or cluster configuration file to name the chassis ServerXYZ:

node.subcluster = ServerXYZ

When you assign the subcluster, you can include more than one multi-server chassis in the same subcluster provided more than one subcluster is used for the whole cluster.

You can use subclusters for other purposes, such as data protection. For example, if you have data centers in separate wings of your building, you can create subclusters to copy content to data centers in both wings to provide high availability in case of a partial building loss. A loss could be events like a fire, flooding, or air conditioning problems.

See Local Area Replication Using Subclusters.