VCAP-CID Study Notes: Objective 1.3

Welcome to the VCAP-CID Study Notes. This is Objective 1.3 in the VCAP-CID blueprint Guide 2.8. The rest of the sections/objectives can be found here.

Bold items that have higher importance and copied text is in italic.

Skills and Abilities

  • Determine how storage and network topologies affect capacity requirements for a vCloud conceptual design
    • I’m not sure if they want you to really deep dive into the actual topologies or they want you to know the limitation of choosing a FiberChannel solution versus choosing a iSCSI/NAS solution. But lets say they really want us to go over topologies:
      • You have different storage topologies (borrowed from a whitepaper from Brocade):
        • Flat SAN
          • Simple redundant pathing, each server is connected to at least two switches, and those switches are connected to all storage devices
        • Mesh SAN
          • Each server connected to a at least two switches that are interconnected together. Any-to-any connections between devices.
        • Core Edge SAN
          • Here you have a core switch, a distribution layer and a edge layer. Similar to many LAN setups.
      • As for network topologies this could have an effect if using VSAN or NFS/iSCSI, and how networks will be interconnected.
    • The different topologies can affect the design and must be taken into account when creating it.
      • Example:
        • Customer has Flat Fiber Channel SAN and that will affect how you many storage arrays you can connect (on the number of ports available and bandwidth of the SAN switches)
        • Customer had Core Edge SAN using NFS with Edge switches connecting to Local Storage and Core Switches directly connecting to main storage as well (figure 4 in the whitepaper). This will affect they storage layout of the design, where tier 1 and tier 2 storage will be located etc.
  • Describe VMware vCloud Director and VMware vSphere functionality and limitations related to capacity.
    • This involves knowing the Configuration Maximums. Most of these maximums are so high that you will never reach them unless you have a very large environment.
    • Here you can read the Configuration Maximum for vSphere 5.1
      VCAP CID 1-3-2
    • This also includes knowing all the features of vCloud and vSphere as they will limit what you can do regarding to capacity. Just to name one, in vSphere 5.1 you can only put 32 datastores in a Datastore cluster and that might limit the size of a Tiered storage pool (and the datastore size is in turn limited to RTO/RPO availability and storage protocol limitations)
      • Please note that vSphere 5.5 allows 64 Datastores for each Datastore Cluster.
  • Given current and future customer capacity requirements, determine impact to the conceptual design.
    • Current and future capacity requirements include CPU, memory, storage, network bandwidth/port capacity. If you can and you have the numbers (eg. APC cooling/PSUs + SW) go for cooling and power as well.
    • The requirements are based on documentation from the customer or a Capacity Planner project for the existing environment.
    • The future capacity is the projected growth of the environment in all these areas, most likely based on numbers from the customer from previous years.
    • For this to impact the conceptual design you might not be able to replicate the amount of data you want to because of bandwidth issues, you will hit vSphere Configuration maximum, to few network ports, not enough power etc.
  • Given a customer datacenter topology, determine impact to the conceptual design.
    • If the customer has multiple datacenters that topology will impact the conceptual design if they will all be used. Bandwidth, connections, Network topology, cooling, power, storage, using stretched clusters are some of the thing you need to consider.
      • Internally to one datacenter this is based on rack space, and cabinets, cooling layout and power grid setups.
  • Given cloud capacity needs, constraints, and future growth potential, create an appropriate high-level topology.
    • Lets use an example:
      • Capacity need is 3-tiered storage layout with 20TB each. Tier 1 is replicated to a recovery site.
      • Constraints include a 50 Mbps link to a recovery site for replication.
      • Future Growth need is 20% each year (4TB each year)
        • As you might suspect you will need to know the bandwidth of the Tier1 workloads to be able to mitigate the risk of the link between the sites will be enough. If the bandwidth is enough, but will not be enough after 2 years, you could either increase link speed, or do it when a certain percentage of the link is used.

VCAP CID 1-3-1

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