# RabbitMQ on Amazon MQ: Disk limit alarm
RABBITMQ\$1DISK\$1ALARM

 Disk limit alarm is an indication that the volume of disk used by a RabbitMQ node has decreased due to a high number of messages not consumed while new messages were added. RabbitMQ will raise a disk limit alarm when the broker's free disk space, identified by Amazon CloudWatch metric `RabbitMQDiskFree`, reaches the disk limit, identified by `RabbitMQDiskFreeLimit`. `RabbitMQDiskFreeLimit` is set by Amazon MQ and has been defined considering the disk space available for each broker instance type. 

 An RabbitMQ on Amazon MQ broker that has raised a disk limit alarm will become unavailable for new messages being published. If you have a publisher and consumer on the same connection, the consumer will also be unavailable to receive messages. When running RabbitMQ in a cluster, the disk alarm is cluster-wide. If one node goes under the limit, all other nodes will block incoming messages. Due to the lack of disk space, your broker might also experience other issues that complicate diagnosis and resolution of the alarm. 

 Amazon MQ will not restart a broker experiencing a disk alarm and will return an exception for `RebootBroker` API operations as long as the broker continues to raise the alarm. 

**Note**  
You cannot downgrade a broker from an `mq.m5` instance type to an `mq.t3.micro` instance type. If you wish to downgrade, you must delete your broker and create a new one.

## Diagnosing and addressing disk limit alarm


 Amazon MQ enables metrics for your broker by default. You can [view your broker metrics](amazon-mq-accessing-metrics.md) by accessing the Amazon CloudWatch console, or by using the CloudWatch API.`MessageCount` is a useful metric when diagnosing the RabbitMQ disk limit alarm. Messages are stored in memory until they are consumed or discarded. A high message count indicates overutilization of disk storage and can lead to a disk alarm. 

 To diagnose the disk limit alarm, use the Amazon MQ Management Console to: 
+  Create a new connection to consume messages published to the queues. 
+  Purge messages from queues. 
+  Delete the queues from your broker. 

**Note**  
It may take up to several hours for the RABBITMQ\$1DISK\$1ALARM status to clear after you take the required actions.

 To prevent the disk limit alarm from reoccurring, you can upgrade your host [ instance type](rmq-broker-instance-types.md) to an instance with additional resources. For information on how to update your broker's instance type see `UpdateBrokerInput` in the Amazon MQ REST API Reference. We also recommend keeping your publishers and consumers on different connections.