Top 5 Planet V12n blog posts week 06

VMware PEX 2010 was great... but it did mean I was extremely busy and didn’t have time to create the top-5. I just picked the 5 best reads this week. Check it out:

• Jason Boche - My VCDX defense experience
  The first 75 minutes is spent “defending” my design.  I’ve got about a 15 slide deck to get through and to use as reference throughout the design defense.  I’d highly recommend putting as much reference as you can in the slide deck which you can yourself refer to during the defense.  It will help illustrate design choices and jog your memory for design elements which you’ve forgotten due to nervousness. The first 5-10 minutes I was pretty nervous and stuttered once or twice during my presentation. After that, I warmed up and it felt more like a good technical discussion with co-workers which I enjoyed.
• Mike La Spina - Running ZFS over NFS as a VMware Store
  In this architecture we are defining a fault tolerant configuration using two physical 1Gbe switches with a quad or dual Ethernet adapter(s). On the OpenSolaris storage head we are using IPMP aka IP Multipathing to establish a single IP address to serve our NFS store endpoint. A single IP is more appropriate for VMware environments as they do not support multiple NFS IP targets per NFS mount point.  IPMP provisions layer 3 load balancing and interface fault tolerance. IPMP commonly uses ICMP and default routes to determine interface failure states thus it well suited for a NAS protocol service layer. In a effort to reduce excessive ICMP rates we will aggregate the two dual interfaces into a single channel connection to each switch. This will allow us to define two test IP addresses for the IPMP service and keep our logical interface count down to a minimum. We are also defining a 2 port trunk/aggregate between the two physical switches which provides more path availability and reduces  switch failure detection times.
• Hany Michael - vSphere In Motion: A Real-World Live Migration Scenario
  I was having a discussion with one of the large enterprises here in Qatar lately, and I was quite surprised to know from them that they are hesitated to migrate their VI3.5 environment to vSphere because of the associated downtime. What surprised me was not the fact that they can’t afford a downtime, I’ve spent 6 years of my career working in the Telecom sector and I know for a fact that 1 second of downtime could mean a disaster, or even translate to a loss of thousand of $$. What surprised me was that they didn’t know that it is possible to do this migration without any downtime!
• Scott Drummonds - Inaccuracy of In-guest Performance Counters
  Every couple of months I receive a request for an explanation as to why performance counters in a virtual machine cannot be trusted. While it is unfairly cynical to say that in-guest counters are never right, accurate capacity management and troubleshooting should rely on the counters provided by vSphere in either vCenter or esxtop. The explanation is too short to merit a white paper but I hope a blog article will serve as the authoritative comment on the subject.
• Bouke Groenescheij - Removevmha
  Today I’ve updated the popular removevmhba script to version 5.0. This version now includes the removal of the drivers in vSphere ESX 4.0 update 1 isos. Thanks to Dinny Davies who did excellent work again on finding a solution for removing them on vSphere ESX4 (he just beat me to it Wink). Check the original ESX 3.x.x version here, and the new ESX 4.x.x document here. Go ahead, grab removevmhba from the downloads section and give it a try. It removes the drivers only during installation, so you don’t need to bother disconnecting your SAN or zone out anything during installation (both Emulex and Qlogic - and also hardware initiated iSCSI adapters). It’s much safer for a scripted installation of ESX using the UDA or EDA. After the installation you will have the drivers (since it is installed as a package) - so you will get connection back to your SAN.