Known Issues

This section collects currently known issues affecting CINECA HPC Cloud systems.

The list below is intended as a quick reference for users who may experience problems on the system. We strongly encourage all users to report any issues they encounter - whether listed here or not - to the user support team.

PCI interfaces restrictions on a single VM

Status: Open | Last Update: 2025-11-05 | Systems: All

Description

There is a restriction imposed by libvirt which allows a maximum of 28 virtual PCI interfaces used for attaching block devices: 2 of these virtual PCIs are used for server needs (mainly boot device) which leaves 26 virtual PCI interfaces available for block device attaching. For this reason, it is possible to attach maximum 26 volumes to an instance created with the default Ubuntu images provided by CINECA.

SOLUTION:

To avoid this issue the solution is to upload a custom image, editing its metadata from Horizon Dashboard as follows: hw_scsi_model = virtio-scsi and hw_disk_bus = scsi.

Docker MTU issues on virtual machines

Status: Open | Last Update: 2025-11-05 | Systems: All

Description

Docker containers built on virtual machines are unable to communicate outside of the vm.

SOLUTION:

To use Docker in your virtual machine please set the MTU value at 1400 in the file /etc/docker/daemon.json.

{

"mtu" : 1400

}

Creating shares from snapshots

Status: Open | Last Update: 2025-11-04 | Systems: ADA

Description

In order to enable the creation of shares from snapshots, the corresponding openstack share-type needs to include the attribute: create_share_from_snapshot_support=True.

On ADA, the value of the attribute was set to False for both share types (generic, and cephfs) until 03/11/2025.

This implies that shares created on ADA before 4th of November 2025 can generate snapshots, but those are unusable since it is not possible to create new shares from them.