VMsafe, announced at VMworld Europe in February, is a set of application programming interfaces designed to allow third-party products to add security to VMware virtual servers without having to run an agent inside each. Here are some key points to keep in mind.

First, to use VMsafe you need Virtual Datacenter OS which includes VMware's latest evolution of its hypervisor technology for servers. VDC-OS is currently in beta test, so release dates are currently unknown. VDC-OS made APIs out of many of the internal features of VMware ESX, so that third parties could add in new security, networking, and management features.

Second, VMsafe is all about the vApp, VMware's new term for either a virtual appliance or a Virtual Machine (VM). A vApp can contain multiple applications and objects, either multiple VMs or ThinApps.

A vApp digitally signed by the proper authority will be able to access the VMsafe API, which will give that vApp the ability to peer into a VM, either its memory, disk, or network.

Unfortunately, VMware hasn't said much about what 'authorized' means in that context. It's not clear who the certifying authority will be, or if the signatures will be used just for installation or for continual use of the vApp.

Personally, I hope a valid signature will be necessary to allow a vApp to continue to function. This would prevent other vApps or tools from modifying the VMsafe vApp after installation and opening security holes after a VM image has already been locked down. VMware and VMsafe partners are currently working out these details.

VMsafe provides antivirus vendors with the ability to deploy a single instance of an antivirus (A/V) application per physical host, rather than requiring one for each virtual server. The theory is that this will decrease overall CPU utilization and increase A/V performance. The demos we saw at VMworld in which one A/V application served all the VMs on single host certainly bore this out. Even with single A/V instances however, I expect there to be some operation issues with respect to I/O performance, and the timing of A/V scans. Currently these issues force full disk A/V scans to be almost serialized on an VMware ESX host.

VMsafe should not be confused with the vNetwork API or vStorage API—a set of interfaces designed to allow simpler integration of VMware virtual infrastructures with third-party products such as the Cisco vSwitch.