OpenShift Container Storage is now OpenShift Data Foundation starting with version 4.9.
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5.6. Creating an Arbiter Volume (optional)
Arbiter volume supports all persistent volume types with better consistency and less disk space requirements. An arbitrated replicated volume, or arbiter volume, is a three-way replicated volume where every third brick is a special type of brick called an arbiter. Arbiter bricks do not store file data; they only store file names, structure, and metadata. The arbiter uses client quorum to compare this metadata with the metadata of the other nodes to ensure consistency in the volume and prevent split-brain conditions.
Advantages of arbitrated replicated volumes:
- Better consistency: When an arbiter is configured, arbitration logic uses client-side quorum in auto mode to prevent file operations that would lead to split-brain conditions.
- Less disk space required: Because an arbiter brick only stores file names and metadata, an arbiter brick can be much smaller than the other bricks in the volume.
For more information about Arbitrated Replicated Volumes, see https://access.redhat.com/documentation/en-us/red_hat_gluster_storage/3.4/html-single/administration_guide/#Creating_Arbitrated_Replicated_Volumes
Before creating the arbiter volume, make sure heketi-client packages are installed.
subscription-manager repos --enable=rh-gluster-3-for-rhel-7-server-rpms
# subscription-manager repos --enable=rh-gluster-3-for-rhel-7-server-rpms
yum install heketi-client
# yum install heketi-client
If you want to upgrade your already existing Heketi server, then see, https://access.redhat.com/documentation/en-us/red_hat_openshift_container_storage/3.10/html-single/deployment_guide/index#upgrade_heketi_rhgs
5.6.1. Creating an Arbiter Volume Copia collegamentoCollegamento copiato negli appunti!
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Arbiter volume can be created using the Heketi CLI or by updating the storageclass file.
5.6.1.1. Creating an Arbiter Volume using Heketi CLI Copia collegamentoCollegamento copiato negli appunti!
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To create an Arbiter volume using the Heketi CLI one must request a replica 3 volume as well as provide the Heketi-specific volume option “user.heketi.arbiter true” that will instruct the system to create the Arbiter variant of replica 3.
For example:
heketi-cli volume create --size=4 --gluster-volume-options='user.heketi.arbiter true'
# heketi-cli volume create --size=4 --gluster-volume-options='user.heketi.arbiter true'
5.6.1.2. Creating an Arbiter Volume using the Storageclass file Copia collegamentoCollegamento copiato negli appunti!
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To create an arbiter volume using the storageclass file ensure to include the following two parameters in the storageclass file:
- user.heketi.arbiter true
- (Optional) user.heketi.average-file-size 1024
Following is a sample storageclass file:
Note
For information about managing arbiter volumes see, Chapter 9, Managing Arbitrated Replicated Volumes