ESXi host reports this message when the latency on the device is higher than the average latency:

Device naa.5000c5000b36354b performance has deteriorated. I/O latency increased from average value of 1832 microseconds to 19403 microsecond

This occurs when either the latency ratio to the last time the log was updated is 30 or if the ratio doubled since the last log. The device latency may increase due to one of these reasons:

If the device latency is too high for a consistent period of time, check the storage performance by verifying the logs on the storage array for any indication of a failure. If failures are logged on the storage array side, take corrective actions. Contact your storage vendor for information regarding checking logs on the array.

Also, check if these messages are generated when there were any scheduled tasks, such as backups or replications, as these can also cause intermittent performance hits.

Overload conditions on the device

If the message is generated because of an overload condition, attempt to reduce the load on the affected storage device.

 

If running a LUN replication tool, pause the task from the storage end and attempt a storage vMotion to a different datastore. This should help improve the I/O operations.

For translated versions of this article, see:

• Español: Rendimiento deteriorado del dispositivo de almacenamiento (2072906)
• Português: Deterioração do desempenho do dispositivo de armazenamento (2037347)
• 日本語: ストレージ デバイスのパフォーマンスが低下した (2079930)
• 简体中文: 存储设备性能降低 (2076267)