I must admit that I had very little time to prepare for this exam, but that said I do have a pretty good home lab environment with two good sized ESXi hosts, iSCSI storage, VLANs and most of the features deployed that are part of the exam blueprint for the VCAP5-DCA. Having previously done the VCAP4-DCA last year I expected much of the same this time around, but I was mistaken. Sure, many of the blueprint topics share common ground but this exam tests your experience with vSphere 5 and you are expected to perform many of the tasks with your eyes shut. Well, not literally although much of it needs to be second nature to you.
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This year I’ve been working on a VMware design for a large enterprise customer, and had various conversations with the solutions team on everything from storage sizing to networking (that was one day!). This prompted me to address one topic that I feel deserves more attention, and that is the Cisco Nexus 1000V. If you are new to the 1000V virtual switch, then you might want to read the guide I published back in April 2012 on How to Deploy the Cisco Nexus 1000V. For now, grab a coffee and let’s begin with load-balancing policies…
VMware View has offered the ability to serve your desktops as linked clones since View 3.0 with View Composer, but with View 5.1 I still get asked many questions about how linked clones work, how snapshots are involved, delta files, and what other files make up each linked clone virtual desktop. You are probably already familiar with VMDK (Virtual Machine Disks) and snapshots, but the process View Composer takes to create linked clones may still be a bit of a mystery to you. Since the addition of View Storage Accelerator (VSA) in View 5.1 there are also some additional files that are created. This article will describe the files used by linked clones.
For my first post of 2013, I have decided to dive straight into sizing for VMware View 5.1. If you are planning a VMware View implementation then at some stage you will need to look at sizing, and calculating factors like how many desktops per View desktop pool, in addition to network configuration and storage considerations. The purpose of this article is to discuss sizing and configuration maximums for VMware View 5.1. Since VMware ESX 3.x, a configuration maximums document has been published by VMware for each version of vSphere that details the supported maximums for networking, compute, storage, vCenter, host, and even vCloud Director. Because there is no single ‘configuration maximums’ document for VMware View 5.1, I have included reference documents and material at the bottom of this article.
This week I passed the VCAP-DCD5 exam, but having already passed the VCAP-DCD4 exam I actually found it a little harder than I expected. I can’t tell you any specifics of the exam itself (other than what is on the blueprint) but I would like to share my own study method with you. You will need to be VCP5 before you can take this exam (the limited time period that excludes this pre-requisite is almost up), but even if you have done the VCAP4-DCA/DCD before, you should take a fresh approach to the DCD5. Something that helped me a lot was my ITIL experience, as I’ve previously had key involvement with Capacity and Availability management, in addition to being ITIL v3 Foundation certified . I’ll touch on this in a moment, but bear in mind that this is a Design exam and not a technical exam. Sure there are many technical areas, such as system requirements that you need to be aware of, but you need to have experience at either producing designs for your own organisation, or consultancy at delivering designs for customers. Without this knowledge, you may struggle with some of the questions around best practice, or picking the ‘best’ answer from multiple possible correct answers.
VMware KB 1027217 details the ports required between all the components in VMware View 5.0, but I noticed there were not any up to date diagrams illustrating this, so I’ve attached the View 5 Ports here. This won’t need much explanation, but a few key points to highlight here:
1. The replica View Connection Server detailed here is not a ‘slimmed down’ Connection Server, as both accept connections from the View Client and can tunnel connections. I’ve simply removed the PCoIP Gateway and HTTP(S) Secure Tunnel to keep the diagram tidy.
2. The JMS (Java Messaging Service) communication between the View Connection Server and Desktop VM (View Agent) is very important and requires that the View Connection servers are on the same low-latency LAN as the desktop VMs. This can also be encrypted with ‘Message Security Mode’ enabled.
3. When using RDP from the Windows View Client, notice that the RDP session is established locally (127.0.0.1) via the View Client which connects to the desktop VM.
4. If using the Security Server as a PCoIP gateway or secure tunnelling for RDP, the connection is established between the View Client and the Security Server, and then between the Security Server and the desktop VM (View Agent). In this configuration, the View Client does not connect to the desktop VM directly via RDP or PCoIP.
Installing the Cisco Nexus 1000V distributed virtual switch is not that difficult, once you have learned some new concepts. Before I jump straight into installing the Nexus 1000V, lets run through the vSphere networking options and some of the reasons you’d want to implement the Nexus 1000V.
vSS (vSphere Standard Switch)
Often referred to as vSwitch0, the standard vSwitch is the default virtual switch vSphere offers you, and provides essential networking features for the virtualisation of your environment. Some of these features include 802.1Q VLAN tagging, egress traffic shaping, basic security, and NIC teaming. However, the vSS or standard vSwitch, is an individual virtual switch for each ESX/ESXi host and needs to be configured as individual switches. Most large environments rule this out as they need to maintain a consistent configuration across all of their ESX/ESXi hosts. Of course, VMware Host Profiles go some way to achieving this but it’s still lacking in what features in distributed switches.
vDS (vSphere Distributed Switch)
So the vDS, also known as DVS (Distributed Virtual Switch) provides a single virtual switch that spans all of your hosts in the cluster, which makes configuration of multiple hosts in the virtual datacenter far easier to manage. Some of the features available with the vDS includes 802.1q VLAN tagging as before, but also ingress/egress traffic shaping, PVLANs (Private VLANs), and network vMotion. The key with using a distributed virtual switch is that you only have to manage a single switch.
Cisco Nexus 1000V
In terms of features and manageability, the Nexus 1000V is over and above the vDS as it’s going to be so familiar to those with existing Cisco skills, in addition to a heap of features that the vDS can’t offer. For example, QoS tagging, LACP, and ACLs (Access Control Lists). Recently I have come across two Cisco UCS implementations which require the Nexus 1000V to support PVLANs in their particular configuration (due to the Fabric Interconnects using End-Host Mode). There are many reasons one would choose to implement the Cisco Nexus 1000V, lets call it N1KV for short
It was announced this morning that the VDCD511 (VCAP5-DCD beta exam) is available to take from 13th February to 2nd March 2012. You can take it at VMware Partner Exchange 2012 in Las Vegas. When the final exam is released, for a limited time you won’t need to have a VCP5 certification as a pre-requisite. Even if you are not planning on taking this exam during the beta invitations, it’s a great opportunity to get studying. The blueprint does subtly differ from the VCAP4-DCD, and as with the previous exam you’ll be expected to understand the VMware design methodology.
Whilst working on a Vblock 300 implementation a few weeks ago I had an interesting conversation with one of the network architects at VCE and we discussed the subject of best practices surrounding 10Gb and 1Gb networking. Traditionally with 1Gb networking it is best practice to separate traffic on your ESX/ESXi hosts with vSwitches (or dvPortGroups) dedicated to each type of traffic (vMotion, Management, Storage, production networking) and typically designs will contain 6 to 8 NIC’s per host. With the introduction of 10Gb networking, I’ve noticed that some implementations have neglected to include some important design considerations regarding the use of 10Gb networking. Lets say for that we present 4 x 10Gb NIC’s to each host (these are vNIC’s in the Cisco UCS world) or we can present 6 x 1Gb NIC’s using traditional methods of separating the traffic into various dvportGroups. Which is best? Can we get away with just 2 x 10Gb NIC’s or do we need more? The key consideration here isn’t how many NIC’s (or vNIC’s) are presented to each host, but rather how much network bandwidth is available to each traffic type (i.e. vMotion, FT Logging, VM traffic) and critically how we control it.
Since the days when exams were written with chalk and slates and blog posts were cave paintings, it is obligatory to share the experience of taking exams within the community. I hope the title didn’t get you too excited as I signed an NDA and really can’t tell you how to pass this exam. But, what I can do is give you advice and help you focus your study where it really matters. For starters, if you are reading this then you are probably wondering about the VCP5 and the VCAP5 exams. I wouldn’t blame you if you are opting to hold on for the release of the VCAP5 exams, but as it stands whilst I write this post we have no idea when they will be released. It’s likely to be next year sometime, but that is a pure guess. Gregg over at TheSaffaGeek has already started compiling some material to help you with studying for the VCAP 5 exams. However, if you have decided to jump straight in and sit the VCAP-DCD4 (VDCD410) exam then here are my thoughts.
This exam is HARD-ass. There are a few peeps that say it’s easy, but I personally found this harder than the VCAP-DCA due to the shear number of questions (113 in total as stated in the blueprint). If you are a native English speaker then you get 3 hours 45 minutes (4 hours for non-native), and the key to passing this exam is primarily being able to skim-read a case study or scenario and understand design requirements, constraints, risks, assumptions and translate these into one or more of the possible answers. If you spend time reading each question in detail then you are likely to run out of time. It’s also a hard exam to study for because it tests your general experience with vSphere and design knowledge, so you are not just remembering where something is configured.