fault tolerance Archives

9 Things You’ll Love About vSphere 6.0

February 2, 2015 by Bob Plankers

vSphere 6.0, finally. It’s been in beta for what seems like an eternity. Betas are like Fight Club, where the first rule of participation is that you may not talk about your participation. But today’s the day that changes, as VMware just announced 6.0. A lot of rough edges were smoothed in this release, and all the limits have increased again (64 hosts per cluster, etc.). Beyond that, though, there’s much to like. Here are nine things I think are pretty neat about 6.0. 1. Centralized Services (PSC, Content Library, Update Manager) VMware has acknowledged that there’s a fair amount of “meta-administration” (my term) that goes on for vSphere. To help curb that they’ve created the Platform Services Controller, which is …

VMware Fault Tolerance, Determinism, and SMP

April 19, 2011 by Bob Plankers

We’re all at least roughly familiar with Fault Tolerance, a feature VMware added to vSphere 4 to establish a mirrored VM on a secondary host. It’s kind of like RAID 1 for VMs. To do this, Fault Tolerance records the inputs to a primary VM, and then replays it on the secondary VM to achieve the same results. There are two important and somewhat subtle points here that help us understand why Fault Tolerance is limited to one CPU. First, the process records the inputs, not the state of the PC after the inputs happen. If you moved the mouse on the primary it moves the mouse on the secondary VM in exactly the same fashion. If you ping the …