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io bandwidth limit is avail in openvz
OpenVZ is an open source virtualization technology for Linux that enables the partitioning of a single physical Linux machine into multiple smaller independent units called containers.
* '''Disk I/O priority'''. Containers compete for I/O operations, and can affect each other if they use the same disk drive. OpenVZ introduces a per-container I/O priority, which can be used to e.g. decrease the "bad guy" I/O rate in order to not trash the other containers.
* '''Disk I/O bandwidth'''. I/O bandwidth (in bytes per second) can be limited per-container . === Memory === All the containers share the same physical memory and swap space, and other similar resources like a page cache. All that memory is managed by a single kernel, thus making memory distribution model very elastic — if memory is not used by one container, it can be used by another. Two major memory resource control parameters that are controlled per container are RAM and swap. If container is off its limit in terms of RAM, kernel tries to free some, by either shrinking the page cache or by swapping out. This reclamation mechanism is the same as used by a non-containerized kernel, the only difference is swap out is "virtual", in a sense that kernel does not write physical pages to the disk, but just removes those from container context (currently only available in commercial Parallels Virtuozzo Containersorder to avoid unnecessary I/O), while slowing down a container (to emulate the effect of real swap out). Next, if a situation of global (not per-container)memory shortage happens, such pages are really swapped out into a swap file on disk. The above memory control mechanism is efficient, easy to use and comprehend by an administrator, and overall very effective.
=== Miscellaneous resources ===
