+++
title = "When upgrading a Bonsai cluster's Elasticsearch or OpenSearch major version, what is the likely impact to availability of the system and what are the possible recovery steps?"
weight = 96
updated = 2023-06-17
aliases = ["/docs/when-upgrading-a-bonsai-clusters-elasticsearch-or-opensearch-major-version-what-is-the-likely-impact-to-availability-of-the-system-and-what-are-the-possible-recovery-steps.html"]

[extra]
nav_title = "Major Version Upgrades"
weight = 60
+++

There are 2 options for a major version upgrade.

**Option 1 - Enterprise Plans**

Schedule a time with our team for us to perform a snapshot-restore process to upgrade a major version. During the process, you can expect a short period (depending on your cluster's disk capacity) of read-only mode. In most cases it takes a few seconds. TitanIAM users will find that it handles retries, so as far as their application is concerned, this would be close to zero-downtime.

The read-only mode would end with an atomic update to the routing layer, sending incoming traffic to the new hardware. This gives our team a fallback path if something goes awry. However, any writes applied between the routing update and fallback are simply lost.

**Option 2 - Non-Enterprise Plans**

Check out our documentation on [Upgrading Major Versions](@/docs/cluster-management/version-upgrades/upgrading-major-versions/index.md). By following our recommended variation of a blue-green strategy outlined in the documentation and assuming you can pause or buffer your updates:

- Version upgrades happen instantaneously
- Can be performed with zero downtime
- Offers recovery steps depending on your use case's approach