[Yandex Cloud documentation](../../index.md) > [Yandex Managed Service for MySQL®](../index.md) > [Step-by-step guides](index.md) > Logs and monitoring > Cluster and host state monitoring # MySQL® cluster and host state monitoring Data on the cluster and host state is available in the [management console](https://console.yandex.cloud). You can view them on the **Monitoring** tab of the cluster management page or in [Yandex Monitoring](../../monitoring/concepts/index.md). Diagnostic information about cluster states is presented as graphs. Chart update rate: * Standard hosts and hosts with an increased RAM to vCPU ratio (`memory-optimized`): 15 seconds. * Hosts with a guaranteed vCPU share under 100% (`burstable`): 150 seconds. {% note info %} The most appropriate multiple units (MB, GB, and more) are automatically used in charts. {% endnote %} You can [configure alerts](#monitoring-integration) in Yandex Monitoring to receive notifications about cluster failures. In Yandex Monitoring, there are two alert thresholds: `Warning` and `Alarm`. If the specified threshold is exceeded, you will receive alerts via the configured [notification channels](../../monitoring/concepts/alerting.md#notification-channel). ## Cluster state monitoring {#monitoring-cluster} To view detailed information on the health state of a Managed Service for MySQL® cluster: {% list tabs group=instructions %} - Management console {#console} 1. Navigate to **Managed Service for MySQL**. 1. Click the name of your cluster and select the **Monitoring** tab. The page that opens will display performance charts for the cluster. To get started with Yandex Monitoring metrics, dashboards, or alerts, click **Open in Monium** in the top panel. The following charts are displayed for a cluster: * **Queries per second**: Number of user queries per second for each cluster host. * **Average query time**: Average query time for each cluster host. * **Slow queries per second**: Number of queries per second that are longer than specified in [long_query_time](../concepts/settings-list.md#setting-long-query-time). The information is displayed for each cluster host. * **Connections**: Number of connections for each cluster host. * **Threads running**: Number of running threads for each cluster host. * **Disk usage**: Disk space usage for each host and the entire cluster. * **Is Primary, [boolean]**: Shows whether the host is the master. * **Is Alive, [boolean]**: Shows the availability of each cluster host. * **Replication lag**: Replica lag time behind the master. * **Free space**: Free disk space for each host and the entire cluster. * **OOM Count**: Number of out-of-memory events on each cluster host. The **Master overview** section shows the master details: * **Query quantiles**: Query execution time, percentiles. * **Threads**: Number of threads. The following is displayed separately: * **Threads cached**: Number of cached threads. * **Threads connected**: Number of open DB connections. The maximum number of open connections is set in [max_connections](../concepts/settings-list.md#setting-max-connections). * **Threads running**: Number of running threads. * **Thread states**: Number of threads in each state. * **Disk usage**: Disk space usage. The following is displayed separately: * **data**: Amount of space used by data. * **default tablespace**: Amount of space used by data in the tablespace. * **innodb logs**: Amount of space used by InnoDB logs. * **relaylogs**, **binlogs**: Amount of space used by MySQL® service logs. * **temp tablespace**: Amount of space used by data in the temporary tablespace. * **undo tablespace**: Amount of space used by data in the [InnoDB undo tablespace](https://dev.mysql.com/doc/refman/8.0/en/innodb-undo-tablespaces.html). * **InnoDB rows operation**: Number of InnoDB row operations. * **InnoDB locks**: Row lock waits in InnoDB. The following is displayed separately: * **innodb_row_lock_current_waits**: Current number of row lock waits. * **innodb_row_lock_waits**: Number of operations with row lock waits per second. * **Temp tables**: Number of temporary tables and files created per second. * **Sorts and joins**: Number of sort and join operations per second. * **Table cache**: Table caching. The following is displayed separately: * **open_tables**: Number of open tables. * **opened_tables**: Number of open tables per second. * **table_open_cache_hits**: Number of open table cache hits per second. * **table_open_cache_misses**: Number of open table cache misses per second. {% endlist %} ## Host state monitoring {#monitoring-hosts} To view detailed information on the state of individual Managed Service for MySQL® hosts: {% list tabs group=instructions %} - Management console {#console} 1. Navigate to **Managed Service for MySQL**. 1. Click the name of your cluster and select the **Monitoring** tab. 1. Navigate to the **Hosts** tab and select the host. The page that opens will display performance charts for the cluster hosts. To get started with Yandex Monitoring metrics, dashboards, or alerts, click **Open in Monium** in the top panel. The following charts are displayed for the hosts: * **CPU usage**: CPU usage percentage by consumption type. * **Memory usage**: RAM usage by consumption type. * **Disk IOPS**: Number of read and write operations per second. * **Network Packets**: Number of packets sent and received over the network per second. * **Network Bytes**: Network data transmit and receive rate. For **Replica** hosts, the **Received** value is normally greater than **Sent** on the **Network Bytes** and **Network Packets** charts. The **MySQL overview** section shows detailed information about the DBMS state on the host: * **Query quantiles**: Query execution time, percentiles. * **Queries per second**: Number of user queries per second. * **Slow queries per second**: Number of queries per second that are longer than specified in [long_query_time](../concepts/settings-list.md#setting-long-query-time). * **Threads**: Number of threads. The following is displayed separately: * **Threads cached**: Number of cached threads. * **Threads connected**: Number of open DB connections. The maximum number of open connections is set in [max_connections](../concepts/settings-list.md#setting-max-connections). * **Threads running**: Number of running threads. * **Thread states**: Number of threads in each state. * **Handlers**: Number of operation handlers. * **Replication lag**: Replica lag time behind the master. * **File IO write bytes**: Data write rate by file type. * **File IO read bytes**: Data read rate by file type. * **Disk usage**: Disk space usage. The following is displayed separately: * **data**: Amount of space used by data. * **default tablespace**: Amount of space used by data in the tablespace. * **innodb logs**: Amount of space used by InnoDB logs. * **relaylogs**, **binlogs**: Amount of space used by MySQL® service logs. * **temp tablespace**: Amount of space used by data in the temporary tablespace. * **undo tablespace**: Amount of space used by data in the [InnoDB undo tablespace](https://dev.mysql.com/doc/refman/8.0/en/innodb-undo-tablespaces.html). * **File IO write operations**: Number of write operations per second by file type. * **File IO read operations**: Number of read operations per second by file type. * **Temp tables**: Number of temporary tables and files created per second. * **Sorts and joins**: Number of sort and join operations per second. * **Table cache**: Table caching. The following is displayed separately: * **open_tables**: Number of open tables. * **opened_tables**: Number of open tables per second. * **table_open_cache_hits**: Number of open table cache hits per second. * **table_open_cache_misses**: Number of open table cache misses per second. * **InnoDB rows operation**: Number of InnoDB row operations. * **InnoDB locks**: Row lock waits in InnoDB. The following is displayed separately: * **innodb_row_lock_current_waits**: Current number of row lock waits. * **innodb_row_lock_waits**: Number of operations with row lock waits per second. * **InnoDB lock time**: Maximum InnoDB row lock wait time. * **InnoDB cache efficiency**: Efficiency of the InnoDB buffer. The following is displayed separately: * **innodb_buffer_pool_reads**: Number of read operations per second where InnoDB had to access the disk. * **innodb_buffer_pool_read_requests**: Total number of read operations per second. * **InnoDB data operations**: Number of InnoDB operations per second. The following is displayed separately: * **innodb data fsyncs**: Number of `fsync()` operations when flushing data to disk. * **innodb data reads**: Number of disk reads. * **innodb data writes**: Number of disk writes. * **SemiSync latency**: Maximum transaction commit latency in [semi-synchronous replication](https://dev.mysql.com/doc/refman/5.7/en/replication-semisync.html). * **Inode usage**: Inode usage as a percentage of the total. Under **MySQL overview** → **Disk Metrics Details**: * **Disk write latency (percentiles)**: Disk write latency, percentiles. * **Disk write bytes**: Average and maximum disk write rate. * **Disk write operations**: Average and maximum number of write operations per second. * **Disk read latency (percentiles)**: Disk read latency, percentiles. * **Disk read bytes**: Average and maximum disk read rate. * **Disk read operations**: Average and maximum number of read operations per second. * **Disk write throttler latency (percentiles)**: Write delay introduced by exceeding disk quota, percentiles. * **Disk read throttler latency (percentiles)**: Read delay introduced by exceeding disk quota, percentiles. * **Disk used quota**: Average and maximum quota used percentage for disk operations. {% endlist %} ## Setting up alerts in Yandex Monitoring {#monitoring-integration} {% list tabs group=instructions %} - Management console {#console} 1. In the [management console](https://console.yandex.cloud), select the folder with the cluster for which you want to set up alerts. 1. Navigate to ![image](../../_assets/console-icons/display-pulse.svg) **Monitoring**. 1. Under **Service dashboards**, select: * **Managed Service for MySQL® — Cluster Overview** to set up cluster alerts. * **Managed Service for MySQL® — Host Overview** to set up host alerts. 1. On the chart of interest, click ![options](../../_assets/console-icons/ellipsis.svg) and select **Create alert**. 1. If the chart displays multiple metrics, select the data query for the relevant metric and click **Continue**. For more on the query language, see [this Yandex Monitoring guide](../../monitoring/concepts/querying.md). 1. Set the `Alarm` and `Warning` alert thresholds. 1. Click **Create alert**. {% endlist %} To have other cluster health indicators monitored automatically: {% list tabs group=instructions %} - Management console {#console} 1. [Create an alert](../../monitoring/operations/alert/create-alert.md). 1. Add a status metric. 1. In the alert parameters, set the alert thresholds. {% endlist %} Recommended threshold values for selected metrics: | Metric | Internal metric name  | `Alarm` | `Warning` | |-------------------------------------|:-------------------------:|:-------------------------:|:-------------------------:| | Replication lag | `mysql_replication_lag` | `600` | `60` | | Number of healthy hosts | `mysql_is_alive` | ` - 2` | ` - 1` | | Average query execution time | `mysql_latency_query_avg` | — | `2,000` | | Storage space used | `disk.used_bytes` | 90% of the storage size | 80% of the storage size | | CPU usage | `cpu.idle` | `10` | `20` | The `Alarm` and `Warning` thresholds for the `disk.used_bytes` metric are specified exclusively in bytes. For example, the recommended values for a 100 GB disk are as follows: * `Alarm`: `96,636,764,160` bytes (90%) * `Warning`: `85,899,345,920` bytes (80%) You can check the current storage size in the [cluster details](cluster-list.md#get-cluster). For a complete list of supported metrics, see [this Monitoring guide](../../monitoring/metrics-ref/managed-mysql-ref.md). ## Cluster health and status {#cluster-health-and-status} The **State** of a cluster shows the health of its hosts, while the **Status** shows whether the cluster is started, stopped, or is at an intermediate stage. To view the health state and status of a cluster: 1. Navigate to **Managed Service for MySQL**. 1. In the cluster row, hover over the indicator in the **Availability** column. ### Cluster health states {#cluster-health} State | Description | Suggested actions :--- | :--- | :--- **ALIVE** | Cluster is operating normally. | No action is required. **DEGRADED** | Cluster is not running at its full capacity: the state of at least one of the hosts is other than `ALIVE`. | Run the diagnostics:If you cannot find the cause yourself, [contact support](https://center.yandex.cloud/support). **DEAD** | The cluster is down: none of its hosts are running. | [Make a support request](https://center.yandex.cloud/support) stating the following: **UNKNOWN** | Cluster state is unknown. | [Make a support request](https://center.yandex.cloud/support) stating the following: ### Cluster statuses {#cluster-status} Status | Description | Suggested actions :--- | :--- | :--- **CREATING** | Preparing for the first start | Wait a while and get started. The time it takes to create a cluster depends on the host class. **RUNNING** | The cluster is operating normally | No action is required. **STOPPING** | The cluster is stopping | After a while, the cluster status will switch to `STOPPED` and the cluster will be disabled. No action is required. **STOPPED** | The cluster is stopped | Start the cluster to get it running again. **STARTING** | Starting the cluster that was stopped earlier | After a while, the cluster status will switch to `RUNNING`. Wait a while and get started. **UPDATING** | Updating the cluster's configuration | Once the update is complete, the cluster will get the status it had prior to the update: `RUNNING` or `STOPPED`. **ERROR** | Error when performing an operation with the cluster or during a maintenance window | If the cluster remains in this status for a long time, [contact support](https://center.yandex.cloud/support). You can see whether a cluster is available by its status. **STATUS_UNKNOWN** | The cluster is unable to determine its status | If the cluster remains in this status for a long time, [contact support](https://center.yandex.cloud/support).