The storage infrastructure is shown in the second drop-down of the tree view. flexVDI supports three kinds of storage Objects: Image Storage, Media Storage and Direct Storage. An Image Storage provides storage for Guests' images. A Media Storage stores installation media (ISO images and flexVDI appliances). Finally, a Direct Storage offers Guests the possibility to directly access a Host's physical disk.
The Image Storage objects are logical storage units for Guests' images. It represents a storage space accessible by a set of Hosts. This space is further divided into Volumes, which store the virtual disks of the Guests. The typical use of an Image Storage is to map a shared disk array and its volumes to the set of Hosts connected to it. flexVDI supports the most common SAN technologies: SAS disk arrays, Fiber Channel, iSCSI...
For now, we will focus on making a local directory available to store Guests' images. If you want to learn how to access a shared storage, refer to the Storage chapter in the Administration Guide.
Volumes in an Image Storage can be internal or external. Internal volumes refer to volumes created and offered by the shared storage cabinet. flexVDI uses the OCFS2 cluster file system to manage internal volumes, and its configuration and management is discussed in the Administration Guide. OCFS2 supports reflinks and fallocate, which are particularly useful to work with large image files.
On the other hand, external volumes are not directly managed by flexVDI. The system administrator is responsible for mounting them in the same path in all the Hosts involved in the Image Storage. The two most common use cases for external volumes are:
- Use local storage in a single Host.
- Use an NFS or CIFS shared folder accessible by a set of Hosts (Beware: neither NFS nor CIFS support fallocate, so creating new images is a slow process).
In the tree view, external volumes are identified by a small white arrow in its icon:
Be careful that the
/home/images directory is read-writable by the qemu user. Otherwise guests will not be able to start.
Click on the External Volume, and you will see something like this in the details view:
Media Storages are repositories of ISO image files. These files can be mounted as disks by Guests and are useful for the initial installation of the OS. At the end of the , you activated the local CIFS server, so you should already have a Media Storage called cifs. Copy some installation ISOs there in order to install a new Guest later. Click on it, and information about it will be displayed in the details view: