On Sat, 1 Apr 2006, David Lesher wrote:
Panix is offering Xen-based virtual servers. I mention same here only because I've seen almost no discussion of virtualized servers, and hope to learn from the surely-resulting flameware....
Xen and similar solutions are gaining popularity because they work on a similar model as that used for ADSL: most users don't use all the resources all the time. By virtualizing, the provider can offer "dedicated colocation" at a somewhat lower cost to the user, and a *much* lower cost to the provider. If properly provisioned, by distributing more heavily loaded virtual machines appropriately, you can probably attain virtualization of 20-30 or more per 2-way or 2-dual-core SMP box and still have CPU left over. Note that Xen in particular has major advantages over some similar products because it eliminates CPU-consuming system trap hackery needed to emulate hardware devices and page-table mappings. Xen is not, however, backed with extensive commercial support (XenSource is still evolving at the moment), lacks easy integration into popular UI/control-panel products, and requires special kernels for the contained OS's (not such a big deal in practice). The current problems haven't stopped some early adopters from trying out Xen. By and large, those who were once using UML[*] and have now tried Xen have switched and not looked back. [*] User Mode Linux, which I went out of my way to heckle (with technically sound arguments, mind you) at an IETF when it was proposed as a method of virtualization. The sad part is, some folks bought the drivel and actually set up businesses using UML as a virtualization layer. -- -- Todd Vierling <tv@duh.org> <tv@pobox.com> <todd@vierling.name>