Installation guide

Release Notes
30
15.1.3. Storage
• Indirect ring entries (spin locks) for the para-virtualized (virtio) driver improve block I/O performance
and allows more concurrent I/O operations.
• Virtualized storage devices can now be added and removed (hot plugged) from guests during
runtime.
• Support for block alignment storage topology awareness. Underlying storage hardware features
and physical storage sector sizes (for example, 4KB sectors) are presented to guests. This feature
requires compatible storage device information and commands. Guest topology awareness allows
virtualized guests to optimize file system layouts and improve performance of applications using I/O
optimizations.
• Performance enhancements for the qcow2 virtualized image format.
15.1.4. Networking
• MSI-X support which increases the number of interrupts available to network devices. MSI-X
support increases the performance of compatible hardware.
• Virtualized network devices can now be hot plugged and hot removed from running guests. Network
boot using gpxe for more advanced PXE network booting.
15.1.5. Kernel SamePage Merging
The KVM hypervisor in Red Hat Enterprise Linux 6 features Kernel SamePage Merging (KSM),
allowing KVM guests to share identical memory pages. Page sharing reduces memory duplication,
allowing a host with similar guest operating systems to run more efficiently.
15.1.6. Device Assignment
Assignment devices can now be hot plugged and hot removed from running guests.
15.1.7. virtio-serial
The para-virtualized serial device (virtio-serial) provides a simple communication interface between
the host's user space and the guest's user space. virtio-serial can be used for communication where
networking is not be available or unusable.
15.1.8. sVirt
sVirt is a new feature included with Red Hat Enterprise Linux 6.0 that integrates SELinux and
virtualization. sVirt applies Mandatory Access Control (MAC) to improve security when using
virtualized guests. sVirt improves security and hardens the system against bugs in the hypervisor that
might be used as an attack vector for the host or to another virtualized guest.
15.1.9. Migration
• Guest ABI stability provides enhanced migration support. Guests PCI device numbers are preserved
during migration and identical PCI device positions are presented after migrating the guest.
• Migration now accounts for CPU models. CPU models allow guests to take advantage of new
processor instruction sets. Guests can be migrated to hosts with a compatible CPU model.
• Enhancements to the migration protocol.