Top 5 Planet V12n blog posts week 05

For a lot of people it has been a crazy week. Some of you might wonder why, some of you know what I’m talking about. VMware Partner Exchange 2010. With PEX coming up for many of you that means GTJD, GTJD? Yeah, Getting The Job Done! Being away for a week in my case means I need to wrap up project and answer a lot of emails before it gets out of control. That doesn’t however mean that I don’t have time to create a top-5.... This weeks list contains the all-star bloggers:

• Scott Drummonds - PVSCSI and Low-IO Workloads
  At low IOPS the CPU is doing very little work to access storage hardware.  In these environments it is simply not worth anyone’s time to implement and use a special driver storage driver.  But when 10-50k IOPS are streaming through the virtual SCSI bus, a new approach that halves the number of cycles spent on each IO will noticeably decrease CPU utilization.  This is why we created PVSCSI. The current design of PVSCSI coalesces based on OIOs only, and not throughput.  This means that when the virtual machine is requesting a lot of IO but the storage is not delivering, the PVSCSI driver is coalescing interrupts.  But without the storage supplying a steady stream of IOs there are no interrupts to coalesce.  The result is a slight increase to latency with little or no efficiency gain.
• Frank Denneman - Sizing VMs and NUMA nodes
  ESX is NUMA aware and will use the NUMA CPU scheduler when detecting a NUMA system. On non-NUMA systems the ESX CPU scheduler spreads load across all sockets in a round robin manner. This approach improves performance by utilizing as much as cache as possible. When using a vSMP virtual machine in a non-NUMA system, each vCPU is scheduled on a separate socket.
• Jason Boche - Configure VMware ESX(i) Round Robin on EMC Storage
  The answer was buried on page 88.  The nmp roundrobin setting useANO is configured by default to 0 which means unoptimized paths reported by the array will not be included in Round Robin path selection unless optimized paths become unavailable.  Remember I said early on that unoptimized and optimized paths reported by the array would be a key piece of information.  We can see this in action by looking at the device list above.  The very last line shows working paths, and only one path is listed for Round Robin use – the optimized path reported by the array.
• Scott Lowe - Using IP-Based Storage with VMware vSphere on Cisco UCS
  From the VMware side of the house, since you’re using 10GbE end-to-end, it’s very unlikely that you’ll need to worry about bandwidth; that eliminates any concerns over multiple VMkernel ports on multiple subnets or using multiple NFS targets so as to be able to use link aggregation. (I’m not entirely sure you could use link aggregation with the 6100XP interconnects anyway. Anyone?) However, since you are talking Cisco UCS you’ll have only two 10GbE connections (unless you’re using the full width blade, which is unlikely).
• Gabe - Licensing problems with VMware VIEW4
  The problem Jon was facing, was that it was impossible to just add those 20 (2×10) licenses to vCenter without assigning them to a host. Because, in our believe, there should just be 20 licenses in some sort of pool that each VDI VM would take one license from. It is possible to assign multiple hosts to one license so they can share the number of available VMs in that license. What you can’t do is have a host connect to more than one license, which in our opinion would also be feasible.