Test Lab

oVirt Framework

Fedora 18 is also delivered with the oVirt framework in the current 3.1 version. With the help of the oVirt engine, a complex cloud management environment can be created independent of the manufacturer. ADMIN magazine presented the framework in detail in a previous article [10]. oVirt version 3.1 in Fedora 18 now supports live snapshots, shared disks, external disks, CPU pinning, jumbo frames, "prestarted" virtual machine pools, and quotas, as well as cloning virtual machines from a snapshot.

oVirt 3.1 also supports hot plugging with disk and network interfaces, as well as Posix filesystem storage. Also, the oVirt framework can connect with Red Hat Directory Server or IBM's Tivoli Directory Server and use remote databases. All-in-one operation makes it possible to run the engine hypervisor on the same machine.

VirtSandbox

The VirtSandbox server tool [11] makes it possible to embed secure container environments in which a service is sealed off from the rest of the system. VirtSandbox allows the admin to confine individual applications in a secure sandbox with the help of KVM (optionally, LXC) as in other sandbox solutions, such as the SELinux sandbox, which has been included in Fedora and Red Hat since 2009.

VirtSandbox is based on virtual machines. The trick is that it is not necessary to set up an operating system in the VM explicitly, because the VM kernel can read parts of the host filesystem directly using the Plan9fs (Plan 9 filesystem). That makes the overhead of the solution very small, so that the time and effort needed to start a confined application using VirtSandbox is of hardly any consequence – Red Hat speaks of a maximum of three seconds compared with a native start of the same application.

In the KVM variation, VirtSandbox starts the kernel together with initramfs in a VM, which in turn calls up the actual application after the boot. According to Red Hat, access to the CPU in VirtSandbox goes largely without a sacrifice in performance, and access to devices lies at about 90 percent of normal speed. The admin sets up the sandbox with the virt-sandbox tool and, for example, specifies which network resources will be available in the sandbox. Many uses are conceivable, such as confining the entire web browser in the virtual sandbox for secure online banking.

System Storage Manager

The new System Storage Manager (SSM) [12] is also very interesting. With it, admins can complete many storage media configuration tasks in a uniform syntax, instead of having to combine tools like fdisk, btrfs, cryptsetup, lvm2, mdadm, or resize2fs. The Fedora admin can, for example, create ext3, ext4, XFS, and Btrfs volumes with the create option or check them with check.

The snapshot option makes a snapshot if the storage medium supports it. SSM can create, expand, or delete LVM, RAID, or Btrfs storage pools, and it can list devices, volumes, or LVM/RAID/Btrfs pools. The resize option enlarges or reduces the size of SSM volumes (Figure 4) or filesystems, and remove deletes them on request. The commands are largely self-explanatory. More information can be found in the man page.

Figure 4: The new System Storage Manager simplifies reducing the size of logical volumes tremendously.

For example, in the classical approach, the fdisk, mkfs, pvcreate, vgcreate, vgdisplay, lvcreate, and lvdisplay commands are all required for the admin to create logical volumes in an LVM volume group; only a single command is needed in SSM. Using ssm list provides a list of all available devices, including any LVM groups or RAID arrays.

In the example, Anaconda automatically creates the LVM group for the Fedora partition during the partitioning, and the same goes for the 500MB boot partition that doesn't belong to the LVM group. Creating a new logical LVM volume can then be achieved with

ssm create -s 4G --fstype ext4 /dev/sdb

This command specifies a logical volume of 4GB and formats it as ext4. The command also automatically creates the /dev/lvm_pool volume group required for this, which can easily be verified with the graphical Logical Volume Manager included in Fedora, provided the system-config-lvm package has been installed.

The tool makes it much easier to complete many scenarios because it does so many things automatically, such as creating a volume group on creation of logical volumes or creating the physical volumes when expanding a volume group. However, the opposite, such as just creating an LVM volume group without automatically creating volumes, is not possible, although you can do this using the classical tools. Restoring LVM snapshots is also not yet possible with SSM. Unfortunately, SSM does not reveal which of the underlying tools it uses itself.