On Thursday, 04/24/2008 at 10:27 EDT, "Gentry, Stephen" <[EMAIL PROTECTED]> wrote: > Ok, I'll ask. Why wouldn't one attach an OSA card directly to a Linux > guest? > Seriously, why shouldn't this be done?
Off the top of my head: (a) Security. You now limit what can be done with the OSA since you give it to a guest to use. You wouldn't want to share it with other guests (IMO). Do you know what low-level functions are available in the OSA? Me neither, but a virtual NIC is designed to prevent a guest from doing things you don't want it to do or limiting the scope of what it does. And I certainly wouldn't even THINK about letting a guest have arbitrary access to all your VLANs unless it is supposed to have that access. (b) High availability. If a guest is handling the OSA, then the guest must handle any OSA, cable, or switch errors or device outages. The VSWITCH handles that transparently for all guests using the VSWITCH. What if you have 5 guests that need OSAs? Each would need a backup as well. (c) Utilization. Who is using the OSA when this guest isn't? Does it sit idle? A VSWITCH operates an OSA on behalf of multiple guests. Alan Altmark z/VM Development IBM Endicott
