Mounting Filesystems
There are two methods available for mounting a filesystem in one of the cluster hosts:
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.
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.
Note: Using the mount command as explained below first requires the installation of the WekaIO client, configuring of the client and joining it to a WekaIO cluster.
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/demomount -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​
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.
​
Command: mount -t wekafs
Use the following command line to invoke the mount command:
mount -t wekafs -o <options> <backend0>[,<backend1>,...,<backendN>]/<fs> <mount-path>
Parameters in Command Line
Name | Type | Value | Limitations | Mandatory | Default |
| ​ | See Additional Mount Options below | ​ | ​ | ​ |
| String | IP/host name of a backend host | Must be a valid name | Yes | ​ |
| String | Filesystem name | Must be a valid name | Yes | ​ |
| String | Path to mount on the local machine | Must be a valid path name | Yes | ​ |
Each mount option can be passed with an individual -o flag to mount
Option | Value | Description | Default |
| None | Set mode to coherent | No |
| None | Set mode to read cache | No |
| None | Set mode to write cache | Yes |
| Positive number, time in milliseconds | After the defined time period, every metadata cached entry is refreshed from the system, allowing the host to take into account metadata changes performed by other hosts. | 1000 |
| Positive number, time in milliseconds | Each time a file or directory lookup fails, an entry specifying that the file or directory does not exist is created in the local dentry cache. This entry is refreshed after the defined time, allowing the host to use files or directories created by other hosts. | 0 |
| None | Mount filesystem as read-only | No |
| None | Mount filesystem as read-write | Yes |
| 32, 64 or auto | Size of the inode in bits, which may be required for 32 bit applications. | Auto |
| None | Write debug logs to the console | No |
| None | Don't show any logs to console | No |
| None | Can be defined per mount (access can only be degraded if there are ACLs defined but the mount has no ACL) | No |
Note: Current ACL support is limited. It does not support inheritance of default ACLs and has some impact on performance.
Option | Value | Description | Default |
| Number | The amount of memory to be used by the client (for huge pages) | 1400 MiB |
| Number | Number of frontend cores to allocate for the client. Either If none are specified, the client will be configured with 1 core. If 0 is specified then you must use | 1 |
| String | This option must be specified for on-premises installation, and must not be specified for AWS installations.
The The gateway itself is optional and does not have to be specified when no routing is required in the data network. In the cluster, device names are generated by the order in which they appear in the command line. For example, if there are two Set | ​ |
| Number | The network bandwidth limitation for the entire container, in Mb/s. This limitation is for all nodes running within the container, and an attempt is made to detect it automatically based on the environment e.g., when in AWS. Setting a per-node limitation can be performed in the container definition file. | Auto-select |
| Number | The number of seconds without connectivity after which the client will be removed from the cluster. Minimum value: 60 seconds. | 86,720 seconds (24 hours) |
Note: These parameters are only effective on the first mount command for each client.
For Example: On-Premise Installations
mount -t wekafs -o num_cores=1 -o net=ib0 backend-host-0/my_fs /mnt/weka
Running this command on a host installed with the WekaIO agent will download the appropriate WekaIO version from the hostbackend-host-0and create a WekaIO container which allocates a single core and a named network interface (ib0). Then it will join the cluster that backend-host-0 is part of and mount the filesystem my_fs on /mnt/weka.
mount -t wekafs -o num_cores=0 -o net=udp backend-host-0/my_fs /mnt/weka
Running this command will use UDP mode (usually selected when the use of DPDK is not available)
For Example: AWS Installations
mount -t wekafs -o num_cores=2 backend1,backend2,backend3/my_fs /mnt/weka
Running this command on an AWS host will allocate two cores (multiple-frontends) and attach and configure two ENIs on the new client. The client will attempt to rejoin the cluster via all three backends used in the command line.
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.
Note: 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 output is enabled, the service is configured to start automatically.
It is now possible to access WekaIO filesystems using thecd /mnt/weka/<fs-name> command.
After the execution of anunmount 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.
Note: By default, the command selects the optimal core allocation for WekaIO. If necessary, contact the WekaIO Support Team to learn how to allocate specific cores to the WekaIO client.
Note: When running in AWS, the instance IAM role must allow the following permissions:ec2:AttachNetworkInterface, ec2:CreateNetworkInterface and ec2:ModifyNetworkInterfaceAttribute..
Note: Memory allocation for a client is predefined. Contact the WekaIO Support Team when it is necessary to change the amount of memory allocated to a client.
WekaIO utilizes the Linux page cache for the mounted filesystem. This allows for better performance when accessing the same files multiple times at around the same time.
It is possible to mount a WekaIO filesystem using the autofs command. This is useful because mounting a WekaIO filesystem can only be performed after the WekaIO system has started running on a host, i.e., it is not possible to mount WekaIO filesystems at boot time by adding them to /etc/fstab.
To get started, install autofs on the host:
# On RedHat/Centosyum install -y autofs
# On Debian/Ubuntuapt-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.autofsecho "* &" > /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.autofsecho "* <backend-1>,<backend-2>/&" > /etc/auto.wekafs
Finally, restart the autofs service:
service autofs restart
Note: 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 output is enabled, the service is configured to start automatically.
It is now possible to access WekaIO filesystems using thecd /mnt/weka/<fs-name> command.
For Example: Thedefaultfilesystem is automatically mounted under/mnt/weka/default.
