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46 lines
1.9 KiB
Markdown
46 lines
1.9 KiB
Markdown
# Scaling your ArangoDB deployment
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The ArangoDB Kubernetes Operator allows easily scale the number of DB-Servers and Coordinators up or down as needed.
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The scale up or down, change the number of servers in the custom resource.
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E.g., change `spec.dbservers.count` from `3` to `4`.
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Then apply the updated resource using:
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```bash
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kubectl apply -f {your-arango-deployment}.yaml
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```
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Inspect the status of the custom resource to monitor the progress of the scaling operation.
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**Note: It is not possible to change the number of Agency servers after creating a cluster**.
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Make sure to specify the desired number when creating CR first time.
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## Overview
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### Scale-up
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When increasing the `count`, operator will try to create missing pods.
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When scaling up, make sure that you have enough computational resources / nodes, otherwise pod will be stuck in Pending state.
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### Scale-down
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Scaling down is always done one server at a time.
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Scale down is possible only when all other actions on ArangoDeployment are finished.
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The internal process followed by the ArangoDB operator when scaling down is as follows:
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- It chooses a member to be evicted. First, it will try to remove unhealthy members or fall-back to the member with
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the highest `deletion_priority` (check [Use deletion_priority to control scale-down order](#use-deletion_priority-to-control-scale-down-order)).
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- Making an internal calls, it forces the server to resign leadership.
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In case of DB servers it means that all shard leaders will be switched to other servers.
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- Wait until server is cleaned out from the cluster.
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- Pod finalized.
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#### Use deletion_priority to control scale-down order
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You can use `.spec.deletion_priority` field in `ArangoMember` CR to control the order in which servers are scaled down.
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Refer to [ArangoMember API Reference](/docs/api/ArangoMember.V1.md#specdeletionpriority-integer) for more details.
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