.. _known_issues_card:

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.

.. card:: PCI interfaces restrictions on a single VM

 +++++

 **Status:** :bdg-danger:`Open` | :octicon:`calendar` **Last Update:** 2025-11-05 | :octicon:`cache` **Systems:** All
  .. dropdown:: :octicon:`info` **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``.

.. card:: Docker MTU issues on virtual machines

 +++++

 **Status:** :bdg-danger:`Open` | :octicon:`calendar` **Last Update:** 2025-11-05 | :octicon:`cache` **Systems:** All
  .. dropdown:: :octicon:`info` **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.

        .. code-block:: json

            {

            "mtu" : 1400

            }

.. card:: Creating shares from snapshots

 +++++

 **Status:** :bdg-danger:`Open` | :octicon:`calendar` **Last Update:** 2025-11-04 | :octicon:`cache` **Systems:** ADA
  .. dropdown:: :octicon:`info` **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.