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Chapter 6. Red Hat Gluster Storage Volumes

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A Red Hat Gluster Storage volume is a logical collection of bricks, where each brick is an export directory on a server in the trusted storage pool. Most of the Red Hat Gluster Storage Server management operations are performed on the volume. For a detailed information about configuring Red Hat Gluster Storage for enhancing performance see, Chapter 13, Configuring Red Hat Gluster Storage for Enhancing Performance

Warning

Red Hat does not support writing data directly into the bricks. Read and write data only through the Native Client, or through NFS or SMB mounts.

Note

Red Hat Gluster Storage supports IP over Infiniband (IPoIB). Install Infiniband packages on all Red Hat Gluster Storage servers and clients to support this feature. Run the yum groupinstall "Infiniband Support" to install Infiniband packages.

Volume Types

Distributed
Distributes files across bricks in the volume.
Use this volume type where scaling and redundancy requirements are not important, or provided by other hardware or software layers.
See Section 6.5, “Creating Distributed Volumes” for additional information about this volume type.
Replicated
Replicates files across bricks in the volume.
Use this volume type in environments where high-availability and high-reliability are critical.
See Section 6.6, “Creating Replicated Volumes” for additional information about this volume type.
Distributed Replicated
Distributes files across replicated bricks in the volume.
Use this volume type in environments where high-reliability and scalability are critical. This volume type offers improved read performance in most environments.
See Section 6.7, “Creating Distributed Replicated Volumes” for additional information about this volume type.
Dispersed
Disperses the file's data across the bricks in the volume.
Use this volume type where you need a configurable level of reliability with a minimum space waste.
See Section 6.8, “Creating Dispersed Volumes” for additional information about this volume type.
Distributed Dispersed
Distributes file's data across the dispersed subvolume.
Use this volume type where you need a configurable level of reliability with a minimum space waste.
See Section 6.9, “Creating Distributed Dispersed Volumes” for additional information about this volume type.

6.1. Setting up Gluster Storage Volumes using gdeploy

The gdeploy tool automates the process of creating, formatting, and mounting bricks. With gdeploy, the manual steps listed between Section 6.3 Formatting and Mounting Bricks and Section 6.8 Creating Distributed Dispersed Volumes are automated.
When setting-up a new trusted storage pool, gdeploy could be the preferred choice of trusted storage pool set up, as manually executing numerous commands can be error prone.
The advantages of using gdeploy to automate brick creation are as follows:
  • Setting-up the backend on several machines can be done from one's laptop/desktop. This saves time and scales up well when the number of nodes in the trusted storage pool increase.
  • Flexibility in choosing the drives to configure. (sd, vd, ...).
  • Flexibility in naming the logical volumes (LV) and volume groups (VG).

6.1.1. Getting Started

Prerequisites

  1. Generate the passphrase-less SSH keys for the nodes which are going to be part of the trusted storage pool by running the following command: 
    # ssh-keygen -f id_rsa -t rsa -N ''
  2. Set up password-less SSH access between the gdeploy controller and servers by running the following command: 
    # ssh-copy-id -i root@server

    Note

    If you are using a Red Hat Gluster Storage node as the deployment node and not an external node, then the password-less SSH must be set up for the Red Hat Gluster Storage node from where the installation is performed using the following command: 
    # ssh-copy-id -i root@localhost
  3. Install ansible by running the following command: 
    # yum install ansible

    Important

    Ensure you install Ansible 1.9* for gdeploy.
  4. You must also ensure the following:
    • Devices should be raw and unused
    • For multiple devices, use multiple volume groups, thinpool and thinvol in the gdeploy configuration file
gdeploy can be installed in two ways:
  • Using a node in a trusted storage pool
  • Using a machine outside the trusted storage pool
Using a node in a cluster

The gdeploy package is bundled as part of the initial installation of Red Hat Gluster Storage.

Using a machine outside the trusted storage pool

You must ensure that the Red Hat Gluster Storage is subscribed to the required channels. For more information see, Subscribing to the Red Hat Gluster Storage Server Channels in the Red Hat Gluster Storage 3.1 Installation Guide.

Execute the following command to install gdeploy: 
# yum install gdeploy
For more information on installing gdeploy see, Installing Ansible to Support Gdeploy section in the Red Hat Gluster Storage 3.1 Installation Guide.

6.1.2. Setting up a Trusted Storage Pool

Creating a trusted storage pool is a tedious task and becomes more tedious as the nodes in the trusted storage pool grow. With gdeploy, just a configuration file can be used to set up a trusted storage pool. When gdeploy is installed, a sample configuration file will be created at: 
/usr/share/doc/ansible/gdeploy/examples/gluster.conf.sample

Note

The trusted storage pool can be created either by performing each tasks, such as, setting up a backend, creating a volume, and mounting volumes independently or summed up as a single configuration.
For example, for a basic trusted storage pool of a 2 x 2 replicated volume the configuration details in the configuration file will be as follows: 
[hosts]
10.0.0.1
10.0.0.2
10.0.0.3
10.0.0.4

[devices]
/dev/vdb

[volume]
action=create
volname=glustervol
transport=tcp,rdma
replica=yes
replica_count=2
force=yes

[clients]
action=mount
hosts=10.0.0.1
fstype=glusterfs
client_mount_points=/mnt/gluster
With this configuration a 2 x 2 replica trusted storage pool with the given IP addresses and backend device as /dev/vdb with the volume name as glustervol can be created.
For more information on possible values, see Section 6.1.7, “Configuration File”
After modifying the configuration file, invoke the configuration using the command: 
# gdeploy -c conf.txt

Note

You can create a new configuration file by referencing the template file available at /usr/share/doc/ansible/gdeploy/examples/gluster.conf.sample . To invoke the new configuration file, run gdeploy -c /path_to_file/config.txt command.
To only setup the backend see, Section 6.1.3, “Setting up the Backend ”
To only create a volume see, Section 6.1.4, “Creating a Volume”
To only mount clients see, Section 6.1.5, “Mounting Clients”

6.1.3. Setting up the Backend

In order to setup a Gluster Storage volume, the LVM thin-p must be set up on the storage disks. If the number of machines in the trusted storage pool is huge, these tasks takes a long time, as the number of commands involved are huge and error prone if not cautious. With gdeploy, just a configuration file can be used to set up a backend. The backend is setup at the time of setting up a fresh trusted storage pool, which requires bricks to be setup before creating a volume. When gdeploy is installed, a sample configuration file will be created at: 
/usr/share/doc/ansible/gdeploy/examples/gluster.conf.sample
Example configuration file: 
[hosts]
10.0.0.1
10.0.0.2

[devices]
/dev/vdb

[disktype]
RAID10

[diskcount]
10

[stripesize]
128
For more information on possible values, see Section 6.1.7, “Configuration File”
After modifying the configuration file, invoke the configuration using the command: 
# gdeploy -c conf.txt

6.1.4. Creating a Volume

Setting up volume involves writing long commands by choosing the hostname/IP and brick order carefully and this could be error prone. gdeploy helps in simplifying this task. When gdeploy is installed, a sample configuration file will be created at: 
/usr/share/doc/ansible/gdeploy/examples/gluster.conf.sample
For example, for a basic trusted storage pool of a 2 x 2 replicate volume the configuration details in the configuration file will be as follows: 
[hosts]
10.0.0.1
10.0.0.2
10.0.0.3
10.0.0.4

[volume]
action=create
volname=glustervol
transport=tcp,rdma
replica=yes
replica_count=2
force=yes
For more information on possible values, see Section 6.1.7, “Configuration File”
After modifying the configuration file, invoke the configuration using the command: 
# gdeploy -c conf.txt

6.1.5. Mounting Clients

When mounting clients, instead of logging into every client which has to be mounted, gdeploy can be used to mount clients remotely. When gdeploy is installed, a sample configuration file will be created at: 
/usr/share/doc/ansible/gdeploy/examples/gluster.conf.sample
Following is an example of the modifications to the configuration file in order to mount clients: 
[clients]
action=mount
hosts=10.70.46.159
fstype=glusterfs
client_mount_points=/mnt/gluster
volname=10.0.0.1:glustervol

Note

If the fstype is NFS, then mention it as nfs-version. By default it is 3.
For more information on possible values, see Section 6.1.7, “Configuration File”
After modifying the configuration file, invoke the configuration using the command: 
# gdeploy -c conf.txt

6.1.6. Configuring a Volume

The volumes can be configured using the configuration file. The volumes can be configured remotely using the configuration file without having to log into the trusted storage pool. For more information regarding the sections and options in the configuration file, see Section 6.1.7, “Configuration File”

6.1.6.1. Adding and Removing a Brick

The configuration file can be modified to add or remove a brick:
Adding a Brick

Modify the [volume] section in the configuration file to add a brick. For example: 

[volume]
action=add-brick
volname=10.0.0.1:glustervol
bricks=10.0.0.1:/mnt/new_brick
After modifying the configuration file, invoke the configuration using the command: 
# gdeploy -c conf.txt
Removing a Brick

Modify the [volume] section in the configuration file to remove a brick. For example: 

[volume]
action=remove-brick
volname=10.0.0.1:glustervol
bricks=10.0.0.2:/mnt/brick
state=commit
Other options for state are stop, start, and force.
After modifying the configuration file, invoke the configuration using the command: 
# gdeploy -c conf.txt
For more information on possible values, see Section 6.1.7, “Configuration File”

6.1.6.2. Rebalancing a Volume

Modify the [volume] section in the configuration file to rebalance a volume. For example: 
[volume]
action=rebalance
volname=10.70.46.13:glustervol
state=start
Other options for state are stop, and fix-layout.
After modifying the configuration file, invoke the configuration using the command: 
# gdeploy -c conf.txt
For more information on possible values, see Section 6.1.7, “Configuration File”

6.1.6.3. Starting, Stopping, or Deleting a Volume

The configuration file can be modified to start, stop, or delete a volume:
Starting a Volume

Modify the [volume] section in the configuration file to start a volume. For example: 

[volume]
action=start
volname=10.0.0.1:glustervol
After modifying the configuration file, invoke the configuration using the command: 
# gdeploy -c conf.txt
Stopping a Volume

Modify the [volume] section in the configuration file to start a volume. For example: 

[volume]
action=stop
volname=10.0.0.1:glustervol
After modifying the configuration file, invoke the configuration using the command: 
# gdeploy -c conf.txt
Deleting a Volume

Modify the [volume] section in the configuration file to start a volume. For example: 

[volume]
action=delete
volname=10.70.46.13:glustervol
After modifying the configuration file, invoke the configuration using the command: 
# gdeploy -c conf.txt
For more information on possible values, see Section 6.1.7, “Configuration File”

6.1.7. Configuration File

The configuration file includes the various options that can be used to change the settings for gdeploy. The following options are currently supported:
  • [hosts]
  • [devices]
  • [disktype]
  • [diskcount]
  • [stripesize]
  • [vgs]
  • [pools]
  • [lvs]
  • [mountpoints]
  • {host-specific-data-for-above}
  • [clients]
  • [volume]
The options are briefly explained in the following list:
  • hosts

    This is a mandatory section which contains the IP address or hostname of the machines in the trusted storage pool. Each hostname or IP address should be listed in a separate line.

    For example: 
    [hosts]
10.0.0.1
10.0.0.2
  • devices

    This is a generic section and is applicable to all the hosts listed in the [hosts] section. However, if sections of hosts such as the [hostname] or [IP-address] is present, then the data in the generic sections like [devices] is ignored. Host specific data take precedence. This is an optional section.

    For example: 
    [devices]
/dev/sda
/dev/sdb

    Note

    When configuring the backend setup, the devices should be either listed in this section or in the host specific section.
  • disktype

    This section specifies the disk configuration that is used while setting up the backend. gdeploy supports RAID 10, RAID 6, and JBOD configurations. This is an optional section and if the field is left empty, JBOD is taken as the default configuration.

    For example: 
    [disktype]
raid6
  • diskcount

    This section specifies the number of data disks in the setup. This is a mandatory field if the [disktype] specified is either RAID 10 or RAID 6. If the [disktype] is JBOD the [diskcount] value is ignored. This is a host specific data.

    For example: 
    [diskcount]
10
  • stripesize

    This section specifies the stripe_unit size in KB.

    Case 1: This field is not necessary if the [disktype] is JBOD, and any given value will be ignored.
    Case 2: This is a mandatory field if [disktype] is specified as RAID 6.
    For [disktype] RAID 10, the default value is taken as 256KB. If you specify any other value the following warning is displayed: 
    "Warning: We recommend a stripe unit size of 256KB for RAID 10"

    Note

    Do not add any suffixes like K, KB, M, etc. This is host specific data and can be added in the hosts section.
    For example: 
    [stripesize]
128
  • vgs

    This section specifies the volume group names for the devices listed in [devices]. The number of volume groups in the [vgs] section should match the one in [devices]. If the volume group names are missing, the volume groups will be named as GLUSTER_vg{1, 2, 3, ...} as default.

    For example: 
    [vgs]
CUSTOM_vg1
CUSTOM_vg2
  • pools

    This section specifies the pool names for the volume groups specified in the [vgs] section. The number of pools listed in the [pools] section should match the number of volume groups in the [vgs] section. If the pool names are missing, the pools will be named as GLUSTER_pool{1, 2, 3, ...}.

    For example: 
    [pools]
CUSTOM_pool1
CUSTOM_pool2
  • lvs

    This section provides the logical volume names for the volume groups specified in [vgs]. The number of logical volumes listed in the [lvs] section should match the number of volume groups listed in [vgs]. If the logical volume names are missing, it is named as GLUSTER_lv{1, 2, 3, ...}.

    For example: 
    [lvs]
CUSTOM_lv1
CUSTOM_lv2
  • mountpoints

    This section specifies the brick mount points for the logical volumes. The number of mount points should match the number of logical volumes specified in [lvs] If the mount points are missing, the mount points will be names as /gluster/brick{1, 2, 3…}.

    For example: 
    [mountpoints]
/rhs/mnt1
/rhs/mnt2
  • brick_dirs

    This is the directory which will be used as a brick while creating the volume. A mount point cannot be used as a brick directory, hence brick_dir should be a directory inside the mount point.

    This field can be left empty, in which case a directory will be created inside the mount point with a default name. If the backend is not setup, then this field will be ignored. In case mount points have to be used as brick directory, then use the force option in the volume section.

    Important

    If you only want to create a volume and not setup the back-end, then provide the absolute path of brick directories for each host specified in the [hosts] section under this section along with the volume section.
    For example: 
    [brick_dirs]
/mnt/rhgs/brick1
/mnt/rhgs/brick2
  • host-specific-data

    For the hosts (IP/hostname) listed under [hosts] section, each host can have its own specific data. The following are the variables that are supported for hosts. 

    * devices - List of devices to use
* vgs - Custom volume group names
* pools - Custom pool names
* lvs - Custom logical volume names
* mountpoints - Mount points for the logical names
* brick_dirs - This is the directory which will be used as a brick while creating the volume
    For example: 
    [10.0.01]
devices=/dev/vdb,/dev/vda
vgs=CUSTOM_vg1,CUSTOM_vg2
pools=CUSTOM_pool1,CUSTOM_pool1
lvs=CUSTOM_lv1,CUSTOM_lv2
mountpoints=/rhs/mount1,/rhs/mount2
brick_dirs=brick1,brick2
  • peer

    This section specifies the configurations for the Trusted Storage Pool management (TSP). This section helps in making all the hosts specified in the [hosts] section to either probe each other to create the trusted storage pool or detach all of them from the trusted storage pool. The only option in this section is the option names 'manage' which can have it's values to be either probe or detach.

    For example: 
    [peer]
manage=probe
  • clients

    This section specifies the client hosts and client_mount_points to mount the gluster storage volume created. The 'action' option is to be specified for the framework to determine the action that has to be performed. The options are 'mount' and 'unmount'. The Client hosts field is mandatory. If the mount points are not specified, default will be taken as /mnt/gluster for all the hosts.

    The option fstype specifies how the gluster volume is to be mounted. Default is glusterfs (FUSE mount). The volume can also be mounted as NFS. Each client can have different types of volume mount, which has to be specified with a comma separated. The following fields are included: 
    * action
* hosts
* fstype
* client_mount_points
    For example: 
    [clients]
action=mount
hosts=10.0.0.10
fstype=nfs
nfs-version=3
client_mount_points=/mnt/rhs
  • volume

    The section specifies the configuration options for the volume. The following fields are included in this section: 

    * action
* volname
* transport
* replica
* replica_count
* disperse
* disperse_count
* redundancy_count
* force
    • action

      This option specifies what action must be performed in the volume. The choices can be [create, delete, add-brick, remove-brick].

      create: This choice is used to create a volume.
      delete: If the delete choice is used, all the options other than 'volname' will be ignored.
      add-brick or remove-brick: If the add-brick or remove-brick is chosen, extra option bricks with a comma separated list of brick names(in the format <hostname>:<brick path> should be provided. In case of remove-brick, state option should also be provided specifying the state of the volume after brick removal.
    • volname

      This option specifies the volume name. Default name is glustervol

      Note

      • In case of a volume operation, the 'hosts' section can be omitted, provided volname is in the format <hostname>:<volname>, where hostname is the hostname / IP of one of the nodes in the cluster
      • Only single volume creation/deletion/configuration is supported.
    • transport

      This option specifies the transport type. Default is tcp. Options are tcp or rdma or tcp,rdma.

    • replica

      This option will specify if the volume should be of type replica. options are yes and no. Default is no. If 'replica' is provided as yes, the 'replica_count' should be provided.

    • disperse

      This option specifies if the volume should be of type disperse. Options are yes and no. Default is no.

    • disperse_count

      This field is optional even if 'disperse' is yes. If not specified, the number of bricks specified in the command line is taken as the disperse_count value.

    • redundancy_count

      If this value is not specified, and if 'disperse' is yes, it's default value is computed so that it generates an optimal configuration.

    • force

      This is an optional field and can be used during volume creation to forcefully create the volume.

    For example: 
    [volname]
action=create
volname=glustervol
transport=tcp,rdma
replica=yes
replica_count=3
force=yes
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