Adding Clients

This page describes how to add clients to a bare-metal cluster.

About Client Hosts

Client hosts are used to running applications that need to access the Weka filesystems. They do not contribute CPUs or drives to the cluster and only connect to the cluster to use its filesystems.

Adding (Stateless) Clients

To use the Weka filesystems from a client host, all that is needed is to call the mount command. The mount command automatically installs the software version, and there is no need to join the client to the cluster.

To mount a filesystem in this manner, first, install the Weka agent from one of the backend instances and then mount the filesystem. For example:

# Agent Installation (one time)
curl http://Backend-1:14000/dist/v1/install | sh

# Creating a mount point (one time)
mkdir -p /mnt/weka

# Mounting a filesystem
mount -t wekafs Backend-1/my_fs /mnt/weka

For the first mount, this will install the Weka software and automatically configure the client. For more information on mount and configuration options, refer to Mounting Filesystems Using the Stateless Clients Feature.

It is possible to configure the client OS to automatically mount the filesystem at boot time. For more information refer to Mounting Filesystems Using fstab or Mounting Filesystems Using autofs.

Note: Clients can be deployed on diskless-servers. They can use RAM for Weka client software and NFS mount for the traces. For more information, contact the Weka Support Team.

Note: The different clients must have a unique IP and FQDN.

Adding (Stateful) Clients Which Are Always Part of the Cluster

Note: It is possible to add instances that do not contribute resources to the cluster but are used for mounting filesystems. It is recommended to use the previously described method for adding client instances for mounting purposes. However, in some cases it could be useful to permanently add them to the cluster, e.g., to use these instances as NFS/SMB servers which are always expected to be up.

Stage 1: Install the Software

Verify that the Weka software is installed on the client host according to the installation instructions. For further information, see Obtaining the Weka Install File and Stage 1 in Weka System Installation Process.

Note: All hosts (clients and backends) in a Weka system cluster must use the same software version. If attempts are made to mix multiple versions, the new hosts will fail to join the cluster.

Stage 2: Joining the Cluster

Command: weka cluster host add

Once the client host is in the stem mode (this is the mode defined immediately after running the install.shcommand), use the following command line on the client host to add it to the cluster:

weka -H <backend-hostname> cluster host add <client-hostname>

Parameters in Command Line

Name	Type	Value	Limitations	Mandatory	Default
backend-hostname	String	IP/hostname of one of the existing backend instances in the cluster	Existing backend IP/FQDN	Yes
client-hostname	String	IP/hostname of the client currently being added	Unique IP/FQDN	Yes

Note: On completion of this stage, the host-ID of the newly added host will be received. Make a note of it for the next steps.

Stage 3: Configuring the Host as Client

Command: weka cluster host cores

To configure the new host as a client, run the following command:

weka cluster host cores <host-id> <cores> --frontend-dedicated-cores=<frontend-dedicated-cores>

Parameters in Command Line

Name	Type	Value	Limitations	Mandatory	Default
host-id	String	Identifier of the host to be added to the cluster	Must be a valid host identifier	Yes
cores	Number	Number of physical cores to be allocated to the Weka client	Maximum 19 cores	Yes
frontend-dedicated-cores	Number	Number of physical cores to be dedicated to FrontEnd processes	For clients, the number of total cores and frontend-dedicated-cores must be equal	Yes, in order to configure a host as a client

Stage 4: Configuring Client Networking

Command: weka cluster host net add

Note: If the new client is to communicate with the Weka system cluster over the kernel UDP stack, it is not necessary to run this command.

If a high-performance client is required and the appropriate network NIC is available, use the following command to configure the networking interface used by the client to communicate with the Weka system cluster hosts:

weka cluster host net add <host-id> <device> --ips=<ips> --netmask=<netmask> --gateway=<gateway>

Parameters in Command Line

Name	Type	Value	Limitations	Mandatory	Default
host-id	String	Identifier of the host to be added to the cluster	Must be a valid host identifier	Yes
device	String	Network interface device name e.g., eth1	Must be a valid network device name	Yes
ips	IP address	The IP address of the new interface	Must be a valid IP address	Yes
gateway	IP address	The IP address of the default routing gateway	The gateway must reside within the same IP network of ips (as described by netmask). Not relevant for IB / L2 non-routable networks.	No
netmask	Number	Number of bits in the netmask, e.g., the netmask of 255.255.0.0 has 16 netmask bits	Describes the number of bits that identify a network ID (also known as CIDR).	No

Note: When configuring an InfiniBand client, do not pass the --ips, --netmask and --gateway parameters.

Note: InfiniBand/Ethernet clients can only join a cluster with the same network technology connectivity. It is possible to mix InfiniBand and Ethernet clients in the same cluster as long as the cluster backends are connected to both network technologies.

Stage 5: Applying the Host Configuration

Command: weka cluster host apply

After successfully configuring the host and its network device, run the following command to finalize the configuration by activating the host:

weka cluster host apply <host-id> [--force]

Parameters in Command Line

Name	Type	Value	Limitations	Mandatory	Default
host-id	Comma-separated string	Identifier of the host to be added to the cluster	Must be a valid host identifier	Yes
force	Boolean	Do not prompt for confirmation		No	Off