This incident has been resolved.

We have restored storage access on all affected cloud servers to normal operating status and continue to monitor the situation.
If your server is still not fully functional, please contact our support at support@upcloud.com.
We apologise for the incident.

We have identified an issue with one of the storage servers in our Singapore data centre. The affected storage disks may have entered a read-only state or caused the cloud server to become unresponsive.
We are working to restore the services and resolve the situation as soon as possible.