On 12-Mar-2013, the Quattor configuration templates for VOBoxes hosted on the Service Consolidation infrastructure (virtual machines hosted by HyperV hypervisors) will be updated to take advantage of the integrated paravirtualization drivers for HyperV hypervisors available in SLC5.9 and SLC6.4.

The next run of SPMA on SLC5.9 Virtual Machines (i.e. SLC5 machines with OSDATE >= 20130125) and SLC6.4 Virtual Machines (i.e. SLC6 machines with OSDATE >= 20130308) will then replace the Microsoft paravirtualization drivers, which were used until now, with the integrated drivers; the integrated drivers will then be loaded at the next reboot.

This change is not expected to affect the proper functioning of any existing Virtual Machine.

The following changes are noticeable however, on SLC5 only:

• disks will be seen as "sda", "sdb" instead of "hda", "hdb" with previous driver versions. This however does not affect normal partition mounts and the change will not affect existing machines -- unless users have unexpectedly performed advanced configuration explicitly referencing "hda" or "hdb" disks, but this seems unlikely. LVM partitions are not affected, even if created manually. Existing partition definitions in CDB do not need to be updated because installation still relies on SLC5.8 PXE images, which keeps referencing disks as "hda"/"hdb" like before.
   
• due to race conditions in the set of RPM operations performed by SPMA, in some cases a SLC5.9 Virtual Machine may attempt to load both integrated and Microsoft drivers at boot. In this case, the integrated drivers will be used and the Microsoft drivers will be not be loaded; however users may notice a message displayed on the console in the early stages of the boot process regarding the inability to initialize the Microsoft drivers ("vmbus" initialization failure). This does not affect in any way the proper functioning of the integrated drivers, and the message can be safely ignored. The situation will be fixed the next time the boot ramdisk is rebuilt (typically by a subsequent kernel upgrade, though one may also explicitly rebuild the ramdisk by running mkinitrd).