Es un copy/paste de la documentación oficial. Copio sólo lo que me interesa, para tenerlo en mente.
5. NEW FEATURES AND IMPROVEMENTS
Parallels Virtuozzo Containers 4.6 includes the following new features and improvements:
New Features
• Disk I/O limits
You can configure the bandwidth a Container is allowed to use for its disk input and output
(I/O) operations by means of the vzctl set –iolimit command. Limiting the disk I/O
bandwidth can help you prevent situations when high disk activities in one Container can slow
down the performance of other Containers on the Hardware...