VMworld session TA3438 – Top 10 Performance improvements in vSphere 4

This was a really interesting session that really broke down a lot of the stuff that was improved in vSphere. VMware likes to talk about how vSphere has however many hundred new features, here’s an interesting list of the highlights:

• IO overhead has been cut in half. Also, IO for a VM can execute on a different core than the VM Monitor is running on. This means a single CPU VM can actually use two CPUs.
• The CPU scheduler is much better at scheduling SMP workloads. 4-way SMP VMs perform 20% petter, and 8-way is about 2x the performance of a 4-way with an Oracle OLTP workload, so performance scales well.
• EPT improves performance a LOT. Turning it on also enables Large Pages by default (which can negatively affect TPS). Applications need to have Large Pages turned on, like SQL (which gains 7% performance)
• Hardware iSCSI is 30% less overhead across the board, Software iSCSI is 30% better on reads, 60% better on writes!
• Storage VMotion is significantly faster, because of block change tracking and no need to do a self-VMotion (Which also means it doesn’t need 2x RAM)
• In vSphere performance between RDM and VMFS is less than 5%, and while this is the same as ESX3.5, performance of a VM on a VMFS volume where another operation (like a VM getting cloned) has improved.
• Big improvement in VDI workloads – a boot storm of 512 VMs is five times faster in vSphere. 20 minutes reduced to 4.
• PVSCSI does some very clever things like sharing the I/O queue depth with the underlying hypervisor, so you have one less queue.
• vSphere TCP stack is improved (I know from other sessions they’re using the new tcpip2 stack end-to-end.
• VMXNET3 gives big network I/O improvements, especially in Windows SMP VMs.
• Network throughput scales much better, 80% performance improvement with 16 VMs running full blast.
• VMotion 5x faster on active workloads, 2x faster at idle.
• 350K IOPS per ESX Host, 120K IOPS per VM.

All reasons to be running vSphere on your infrastructure today.