Overview

There are two methods available for mounting a filesystem in one of the cluster hosts:

1. Using the traditional method: See below and also refer to Adding Clients (Bare Metal Installation) or Adding Clients (AWS Installation), where first a client is configured and joins a cluster, after which a mount command is executed.

2. Using the Stateless Clients feature: See Mounting Filesystems Using the Stateless Clients Feature below, which simplifies and improves the management of clients in the cluster and eliminates the Adding Clients process.

This page describes both these options.

Traditional Method for Mounting a Filesystem

To mount a filesystem on one of the cluster hosts, let’s assume the cluster has a filesystem called demo. To add this filesystem to a host, SSH into one of the hosts and run the mountcommand as the root user, as follows:

mkdir -p /mnt/weka/demo
mount -t wekafs demo /mnt/weka/demo

The general structure of amount command for a WekaIO filesystem is:

mount -t wekafs [-o option[,option]...]] <fs-name> <mount-point>

There are three options for mounting a filesystem on a cluster client: coherent, read cache and write cache. Refer to the descriptions in the links below to understand the differences between these modes:

• ​Coherent mount mode​

• ​Read cache mount mode​

• ​Write cache mount mode​

Mounting Filesystems Using the Stateless Clients Feature

The Stateless Clients feature defers the process of joining the cluster until a mount is performed. Simplifying and improving the management of clients in the cluster, it removes tedious client management procedures, which is particularly beneficial in AWS installations where clients may join and leave in high frequency. Furthermore, it unifies all security aspects in the mount command, eliminating the search of separate credentials at cluster join and mount.

To use the Stateless Clients feature, a WekaIO agent must be installed. Once this is complete, mounts can be created and configured using the mount command, and can be easily removed from the cluster using the unmount command.

Assuming the WekaIO cluster is using the backend IP of 1.2.3.4, running the following command as root on a client will install the agent:

curl http://1.2.3.4:14000/dist/v1/install | sh

On completion, the agent is installed on the client machine.

Invoking the Mount Command

Command: mount -t wekafs

Use the following command line to invoke the mount command:

mount -t wekafs -o <options> <backend0>[,<backend1>,...,<backendN>]/<fs> <mount-point>

Parameters in Command Line

Mount Command Options

Each mount option can be passed with an individual -o flag to mount.

For All Clients Types

Additional Mount Options Available using the Stateless Clients Feature

Any subsequent mount commands after the first mount command (where the client software is installed and the host joins the cluster) can use the same command, or use just the traditional mount parameters as defined in Mounting Filesystems, since it is not necessary to join a cluster.

It is now possible to access WekaIO filesystems via the mount-point, e.g., by cd /mnt/weka/ command.

After the execution of anumount command which unmounts the last WekaIO filesystem, the client is disconnected from the cluster and will be uninstalled by the agent. Consequently, executing a new mount command requires the specification of the cluster, cores and networking parameters again.

Mounting Filesystems Using fstab

Edit /etc/fstab file to include the filesystem mount entry:

• A comma-separated list of backend hosts, with the filesystem name

• The mount point

• Filesystem type - wekafs

• Mount options:

  • Configure systemd to wait for the weka-agent service to come up, and set the filesystem as a network filesystem, e.g.:

    • x-systemd.requires=weka-agent.service,x-systemd.mount-timeout=infinity,_netdev

  • Any additional wekafs supported mount option

# create a mount point 
mkdir -p /mnt/weka/my_fs
​
#edit fstab file
vi /etc/fstab
​
#fstab
backend-0,backend-1,backend-3/my_fs /mnt/weka/my_fs  wekafs  x-systemd.requires=weka-agent.service,x-systemd.mount-timeout=infinity,_netdev   0       0

Reboot the machine for the systemd unit to be created and marked correctly.

The filesystem should now be mounted at boot time.

Mounting Filesystems Using autofs

It is possible to mount a WekaIO filesystem using the autofs command.

To get started, install autofs on the host:

# On RedHat/Centos
yum install -y autofs

# On Debian/Ubuntu
apt-get install -y autofs

Then run the following commands to create the autofs configuration files for WekaIO filesystems:

echo "/mnt/weka   /etc/auto.wekafs -fstype=wekafs" > /etc/auto.master.d/wekafs.autofs
echo "*   &" > /etc/auto.wekafs

Or run the following commands for stateless clients (which require the backend names as parameters):

echo "/mnt/weka   /etc/auto.wekafs -fstype=wekafs,num_cores=1,net=<netdevice>" > /etc/auto.master.d/wekafs.autofs
echo "*   <backend-1>,<backend-2>/&" > /etc/auto.wekafs

Finally, restart the autofs service:

service autofs restart

The configuration is distribution-dependent, and it is necessary to ensure that the service is configured to start automatically after the host is rebooted. To verify that the autofs service automatically starts after restarting the server, run the following command: systemctl is-enabled autofs. If the output is enabled the service is configured to start automatically.

In Amazon Linux, for example, autofs service can be verified with chkconfig command. If the output is on for the current runlevel (can be checked with runlevel command), autofs will be enabled upon reboot.

# chkconfig | grep autofs
autofs         0:off 1:off 2:off 3:on 4:on 5:on 6:off

It is now possible to access WekaIO filesystems using thecd /mnt/weka/<fs-name> command.