Virtualization - VMware Clusters and Blade Servers

Blade chassis help further consolidate the data-center footprint and provide an excellent platform to run virtualization; this further consolidates the data-center footprint.  I have noticed on a variety of installations the failure to ensure proper placement of the primary nodes when installing a VMware cluster on blade chassis technology. Primary placement is critical to ensure the availability of VMs in the event of a blade chassis failure. There are 5 primary nodes per cluster and these are selected as the nodes are added to the cluster. Primary nodes holds all cluster settings and node states and this is replicated to all primaries. Secondary nodes do not become primary nodes if a primary node were to fail. Heartbeats are sent from primary to primary nodes and from secondary to primary nodes. If a primary node fails and is not removed then no secondaries become primaries, but if a failed primary node is removed from the cluster than a secondary node  becomes a primary node - the selection of which secondary node becomes a primary node is random further complicating the balancing of primary nodes. The diagram below shows 3 blade chassis's running in RACK A leveraging VMware, the diagram below shows the problems that happen when improper placement of the primary nodes is not followed. In the case below the blade chassis's are HP C7000 series. The installation of ESX is completed in the order of the blade server slots assigned by the blade chassis and all 5 primary nodes end up on one blade chassis (the installation includes adding the nodes to the cluster). The issues identified in the diagram.

Virtualization - Zero Impact Maintenance

Leveraging Virtualization to provide zero impact maintenance during production hours.

 

Before performing maintenance on the physical node in question you need to migrate the VM over to another physical node. This step is non-disruptive to the production environment and the VM continues to provide services.

The migration happens fairly quickly with zero impact. You have to ability to migrate VM's either hot or cold but typically your VM's are running in production environment and cannot tolerate down time; therefore most administrators migrate them hot.

FCoE - Convergance

FCoE (Fibre Channel over Ethernet) allows companies to further converge their infrastructure reducing the complexity and costs.

• Reduction in Cables and Switches
• Reduction in Interface Cards
• Reduction in Power and Cooling

FCoE runs on your data network and removes the need to have a separate Fibre channel infrastructure. FcoE is not routable and will not extend across routed IP networks. FCoE runs on top of Ethernet and enhancements to Ethernet were required in order to prevent frame loss (PFC). The new enhancements to Ethernet are referred to as Lossless Ethernet.

• Priority Flow Control (802.1Qbb)

Additional enhancements to Ethernet may include (dependent on the vendor)

• Bandwidth Management (802.1Qaz)
• Congestion Management (802.1Qau)
• Shortest Path Bridging (802.1aq)

Servers leverage CNA (Converged Network Adapter) with contains both the NIC (Network Interface Card) and HBA (Host Bus Adapter). CNAs have 1 or more ports.

Note: The diagram below is NOT meant to show redundancy.

Introduction to QFabric