Kubernetes: How to increase ephemeral-storage
Is it may be connected with the fact that all the volumes have a limit of 7.4 GB?
You really have a single volume /dev/vda1 and multiple mount points and not several volumes with 7.4GB
Not sure where you are running Kubernetes but that looks like a virtual volume (in a VM). You can increase the size in the VM configuration or cloud provider and then run this to increase the size of the filesystem:
ext4:
$ resize2fs /dev/vda1xfs:
$ xfs_growfs /dev/vda1
Other filesystems will have their own commands too.
The most common issue for running out of disk space on the master(s) is log files, so if that's the case you can set up a cleanup job for them or change the log size configs.