[Yandex Cloud documentation](../index.md) > [Yandex Managed Service for OpenSearch](index.md) > Inspections and recommendations

# Inspections and recommendations in Managed Service for OpenSearch 

Managed database clusters regularly undergo diagnostics to detect possible issues, increase the cluster's reliability, and improve its performance. The results of such checks are displayed as inspections under **Recommendations**. You can see notifications about successful checks and recommendations on eliminating discovered risks. The responsibility to troubleshoot any detected issues lies within the Yandex Cloud user's [remit](../overview/concepts/mdb-responsibilities.md).

All checks have a severity level:

* High level: Criteria of high cluster availability, significant risks of reduced performance, data loss risks. Such checks warrant special attention and require following the recommendations provided. 
* Moderate level: Possible risks of reduced performance, suboptimal memory and disk space usage.
* Low level: Potential risks and cluster operation limitations.

The list of recommendations is updated regularly. For each recommendation, the following timestamps are fixed: the date of the risk's first detection and the date of the most recent status update on this issue. If the recommendation seems to be excessive or incorrect, you can hide it, specifying a reason. Once the hiding period expires, the recommendation will automatically become available again if the issue persists.

Recommendations are available at the cluster, folder, and cloud levels and provide tips for all your resources. However, the absence of recommendations does not mean that your cluster is optimized: the list of checks gets continuously appended but still remains incomprehensive and cannot replace monitoring, since it is **targeted at detecting patterns rather than specific issues**. You can additionally run cluster performance diagnostics and analyze monitoring metrics.

Managing recommendations in Managed Service for OpenSearch requires the [managed-opensearch.editor role or higher](security/index.md).

## Available inspections in Managed Service for OpenSearch {#mos-recommendations}

| **Category** | **Check** | **Risk** | **Severity** |
|---------------------|-----------------------------------------------|---------------------------------------------------------------------------------------------------------|-----------------|
| Performance | CPU usage | [Risk of reduced performance](#opensearch_cpu_idle) | High         |
| High availability | Database version updates | [Database version is out of date](#opensearch_deprecated_version) | High         |
| High availability | Autoscaling feature | [Disk space autoscaling is not configured](#opensearch_disk_autoscaling) | Low          |
| High availability | Autoscaling feature (restrictions) | [Disk space autoscaling is restricted](#opensearch-disk-autoscaling-limit) | Moderate       |
| High availability | Allocating disk space | [Risk of cluster unavailability](#opensearch_disk_free_space) | High         |
| High availability | Memory allocation | [Lack of RAM](#opensearch_oom) | High         |
| High availability | High cluster availability during zone failure | [Risk of data loss and cluster unavailability in the event of a zone failure](#opensearch_high_availability) | High         |

### Risk of reduced performance {#opensearch_cpu_idle}

**Description**

The host continuously uses all CPU resources, which may cause delays in query processing. Check the [load](operations/monitoring.md) and optimize your queries (which may include using the WebSQL [AI assistant](../websql/operations/ai-assistant.md)) or increase the cluster's computing resources.

**Action**

To increase the cluster's computing resources:

1. [Navigate](https://console.yandex.cloud/link/managed-opensearch) to **Managed Service for OpenSearch**.
1. Click the name of your cluster and select the **Node groups** tab.
1. Click ![image](../_assets/console-icons/ellipsis.svg) in the row with the group you need and select **Edit**.
1. Select a host class with the required amount of vCPUs.
1. Click **Save changes**.

### Database version is out of date {#opensearch_deprecated_version}

**Description**

Database version is out of date. Support for the version was officially discontinued. Clusters are running, but support is limited. We recommend upgrading to a supported version.

**Action**

To upgrade the database version:

1. In the [management console](https://console.yandex.cloud), navigate to the folder page.
1. Navigate to **Managed Service for OpenSearch**.
1. Select the cluster and click **Edit**.
1. In the **Version** field, select the OpenSearch version you need.
1. Click **Save**.

For more on supported database versions, see [Database version control policy](concepts/update-policy.md).

### Disk space autoscaling is not configured {#opensearch_disk_autoscaling}

**Description**

Disk space autoscaling is not configured in shards. Configure autoscaling to prevent disk overflow.

**Action**

To increase the disk size:

1. [Navigate](https://console.yandex.cloud/link/managed-opensearch) to **Managed Service for OpenSearch**.
1. Click the name of your cluster and select the **Node groups** tab.
1. Click ![image](../_assets/console-icons/ellipsis.svg) in the row with the group you need and select **Edit**.
1. In the **Increase size** field, set the conditions for autoscaling.
1. Click **Save changes**. 

### Disk space autoscaling is limited {#opensearch-disk-autoscaling-limit}

**Description**

The disk autoscaling limit has been reached, so the cluster cannot increase its disk space when needed. Change the autoscaling settings in the cluster and increase the limit.

**Action**

To increase the disk size:

1. [Navigate](https://console.yandex.cloud/link/managed-opensearch) to **Managed Service for OpenSearch**.
1. Click the name of your cluster and select the **Node groups** tab.
1. Click ![image](../_assets/console-icons/ellipsis.svg) in the row with the group you need and select **Edit**.
1. Specify the maximum storage size after the expansion.
1. Click **Save changes**.

### Risk of cluster unavailability {#opensearch_disk_free_space}

**Description**

Your host is low on free space. Some operations may be disabled, while the whole cluster may become unavailable, i.e., switch to read-only mode. Increase the disk size or clear unused data.

**Action**

To increase the disk size:

1. [Navigate](https://console.yandex.cloud/link/managed-opensearch) to **Managed Service for OpenSearch**.
1. Click the name of your cluster and select the **Node groups** tab.
1. Click ![image](../_assets/console-icons/ellipsis.svg) in the row with the group you need and select **Edit**.
1. In the disk type settings, increase the disk size.
1. Click **Save changes**.

### Not enough RAM {#opensearch_oom}

**Description**

The cluster is running out of RAM, which leads to slow performance or emergency shutdowns. Increase the cluster's RAM.

**Action**

To increase the amount of RAM:

1. [Navigate](https://console.yandex.cloud/link/managed-opensearch) to **Managed Service for OpenSearch**.
1. Click the name of your cluster and select the **Node groups** tab.
1. Click ![image](../_assets/console-icons/ellipsis.svg) in the row with the group you need and select **Edit**.
1. Select a host class with the required amount of RAM.
1. Click **Save changes**.

### Risk of data loss and cluster unavailability in the event of a zone failure {#opensearch_high_availability}

**Description**

The cluster does not provide high availability and is not covered by an SLA. Most hosts reside in a single availability zone. The cluster is not protected: the system does not block risky changes to cluster and index settings, such as specifying links to non-existent availability zones or node groups in shard placement rules. Enable protection to prevent dangerous changes. To ensure SLA compliance, you must configure two or more hosts with the `DATA` role and three or more hosts with the `MANAGER` role; all in different availability zones, where no zone contains more than half of all hosts with each role.

To check for possible risks, run this command:

`curl --user user:pass -X POST https://url/_plugins/_security/availability_guard/analyze -d '{}'`

**Action**

To add a host to another zone:

1. [Navigate](https://console.yandex.cloud/link/managed-opensearch) to **Managed Service for OpenSearch**.
1. Click the name of your cluster and select the **Node groups** tab.
1. Click ![image](../_assets/console-icons/ellipsis.svg) in the row with the group you need and select **Edit**.
1. Update the host placement across availability zones.
1. Finish configuring the host and click **Save**.