Hello Readers, with some delay, this is a Part 4 of ‘Interviewing for VMware vSphere Support Engineer job role’ series of posts.
In previous part I covered questions for a Second Level Support engineer, in this part I will talk about the Third level.
Third Level (Level 3) vSphere support engineer.
First lets talk about what this role is about in my team. You can think of a third level engineer role as of something in between last level support and architectural roles. Third level guys are very often involved in project works and are working directly with Architects. Third level support guys should be able to take architectural decisions, and explain why those decisions were taken. At the same time they should be able to implement all configurations defined in that decision. One of the usual (but not mandatory) requirements to become the third level in my team is VCAP-DCA and VCAP-DCD exams successfully passed.
As you can imagine, questions I ask to those guys are not only technical. I try to come up with questions to see their decision taking skills as well. Lets just jump in to it and take a look on some examples.
Question: What is the default PSP for IBM SVC running firmware version 7.1 in vSphere 5.5? Where can you find this information?
This question is quite confusing. You can hardly find anyone who can answer this question directly, unless it is someone with years of experience at IBM. But that’s not what I am after here. What I want to see is: first, if the candidate knows the terms and abbreviations, and second and most important is how he will try to find the information required. As an interviewer, feel free to replace the IBM SVC with any storage vendor used in your company.
Scenario: You are working on a design for a small company. You are now designing Storage part. You have following information.
ESXi hosts config:
Dual Intel Xeon E5-2650 CPU
128GB of Memory
Two Dual port NICs with total of 4 1G network interfaces.
Assumption: Customer environment uses existing iSCSI SAN
Requirement 1: Connection to storage should be redundant
Requirement 2: Storage IO should be distributed across all available HBAs
Come up with a Virtual Switch design for this solution. Ask questions to the interviewer to clarify missing information. List implementation steps to perform the configuration you described.
This may look somehow familiar to some of the readers. The scenario looks like a simple design scenario from the VCDX panel. It also looks like some of the questions on VCAP-DCD exam. Of course the level of complexity is nothing even close to those.
Next set of questions is theoretical, its purpose is to check if the candidate has deep understating of HA clustering technology on vSphere.
Question: How is the Master host elected in vSphere HA cluster?
Question: What does Host Isolation mean, how is it determined, what are the consequences and what can be done to avoid host isolation?
Question: What is HA ‘Slot size’, in which cases it is used and how is ‘Slot size’ calculated?
Understanding HA is very important when building vSphere environments, everything in IT is about availability.
Scenario: You are required to evaluate a vSphere environment which was build by an external consultant. Customer complains that environment does not perform as expected. According to the customer, every time during patching, at the moment when host is starting to enter the ‘Maintenance Mode’ its gets disconnected form vCenter. After some time, the host reconnects itself. No HA related event is reported.
You are provided with following technical specifications:
Cluster consists of 4 ESXi hosts
Host1D1 and Host2D1 are located in Datacenter 1
Host3D2 and Host4D2 are located in Datacenter 2
HA and DRS are enables for this cluster with default settings
There is a 1G shared connection between 2 Datacenters
High speed dedicated FC SAN is used for Storage
Evaluate technical details. Ask questions to clarify the unclear points. Explain how you would troubleshoot this situation.
Idea for this kind of troubleshooting scenario is again taken from VCAP-DCA and VCDX exams. Although the situation is much simpler. The purpose of this scenario is to evaluate the way candidate thinks, then some troubleshooting. The candidate is expected to ask questions for the points which are not clear. It is not required to come up with a solution.
Scenario: You need to urgently migrate a VM from one cluster to another. Although the VM is not in production it is very important to migrate it without downtime. After several checks you discover that vMotion network for the hosts in two clusters are on different VLANs which are not able to communicate with each other. Bellow is a screenshot of the environment you are working on.
Come up with a fast solution on how to migrate VMs from cluster Dev to cluster Temp.
This scenario helps to determine how fast the candidate can come up with a solution. Sometime with a non standard one.
These are all the question which came to my mind today. Of course there are much more out there. Share the questions you ask in your interviews in comments, I will be happy to read those.
In the next and last part of these series, my colleague Marek Duris will share the questions you may consider to ask to probe candidate’s business attitude.
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