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ClickHouse Volume Expansion
This guide will give an overview on how KubeDB Ops-manager operator expand the volume of various component of ClickHouse
.
Before You Begin
- You should be familiar with the following
KubeDB
concepts:
How Volume Expansion Process Works
The following diagram shows how KubeDB Ops-manager operator expand the volumes of ClickHouse
database components. Open the image in a new tab to see the enlarged version.
The Volume Expansion process consists of the following steps:
At first, a user creates a
ClickHouse
Custom Resource (CR).KubeDB
Provisioner operator watches theClickHouse
CR.When the operator finds a
ClickHouse
CR, it creates required number ofPetSets
and related necessary stuff like secrets, services, etc.Each PetSet creates a Persistent Volume according to the Volume Claim Template provided in the petset configuration. This Persistent Volume will be expanded by the
KubeDB
Ops-manager operator.Then, in order to expand the volume of the various components (ie. Combined, Broker, Controller) of the
ClickHouse
, the user creates aClickHouseOpsRequest
CR with desired information.KubeDB
Ops-manager operator watches theClickHouseOpsRequest
CR.When it finds a
ClickHouseOpsRequest
CR, it halts theClickHouse
object which is referred from theClickHouseOpsRequest
. So, theKubeDB
Provisioner operator doesn’t perform any operations on theClickHouse
object during the volume expansion process.Then the
KubeDB
Ops-manager operator will expand the persistent volume to reach the expected size defined in theClickHouseOpsRequest
CR.After the successful Volume Expansion of the related PetSet Pods, the
KubeDB
Ops-manager operator updates the new volume size in theClickHouse
object to reflect the updated state.After the successful Volume Expansion of the
ClickHouse
components, theKubeDB
Ops-manager operator resumes theClickHouse
object so that theKubeDB
Provisioner operator resumes its usual operations.
In the next docs, we are going to show a step-by-step guide on Volume Expansion of various ClickHouse database components using ClickHouseOpsRequest
CRD.