Virtual CPU changes can now be seen by guests as the number of sockets and number of cores, where previously guests could only see sockets (and one socket equals one core). Now it's possible to do such things as have the VM detect two sockets with two cores for a total of four CPUs — with advance settings. Instructions on this aren't particularly clear. Sadly, there's still a limit of eight vCPUs per VM, as well.
VMware's vCenter also tracks more storage statistics. We found more console info and tracking on throughput and latency for both hosts and VMs. And to our happiness, vCenter now tracks NFS stats as well.
VMware's vNetwork Distributed Switch (available only in the vSphere Enterprise Plus edition) adds network control, by protocol throttling in the switch. Similarly, storage I/O can be throttled as well, per VM, but this also requires the Enterprise Plus Edition.
As an example, we could limit iSCSI, FT (fault tolerance mirroring), NFS, as well as vMotion traffic. The control over both networking and storage resources allows administrative control over each VM. With vCenter, behavior becomes more molecularly confined, and therefore predictable so that machines can be further optimized with VMs.
VMware says that vCenter can now manage up to 1,000 hosts, and 10,000 powered on VMs. VMware also increased the number of VMs per cluster, from 1,280 to 3,000.
There's another claim that vMotion migration is five times faster. We were unable to corroborate this, but we did find that vMotion no longer queues jobs, one behind the other, it actually runs concurrent VM transfers from one host to another. We're inclined therefore, to believe the claims.
VMware 4.1 has new support for 8GBps Fibre Channel. There's also a vStorage API that supports more rapid array file movement through efficient space allocation. In turn, VMs are more rapidly created and provisioned through their life cycle.
VMware stressed in their pre-release briefing that many of the upgrades in VMware 4.1 were incremental, and related to extensibility and scalability. On most fronts, we found this to be true. If you had reasons to buy VMware 4.0, there are more reasons to buy VMware 4.1 for added scale and features. With Microsoft and Citrix breathing down their necks, VMware distinguishes itself by these incremental additions. Many of the juicier updated features and specs are available only in the Enterprise Plus Edition.
Henderson is principal researcher and Allen is a researcher for ExtremeLabs in Indianapolis. They can be reached at firstname.lastname@example.org.