Yearly Archives: 2011

VCAP exams on vSphere 5 – worth waiting for?

VCAP, Virtualisation, VMware, ,

At the London VMUG yesterday there was a presentation about VMware certification by Scott Vessey, a well known VMware trainer (@vmtraining or http://vmwaretraining.blogspot.com/). After his presentation one question raised was whether it’s worth taking the vSphere 4 track or maybe delaying a while and jumping straight to the upcoming vSphere 5 track. Scott said this was a common question so I thought I’d add my thoughts on why I wouldn’t wait;

  • vSphere 5 (as it’s commonly known but not it’s final name) is slated for release around July/August this year (according to this article from the recent VMware Partner Exchange).  Even assuming they hit this deadline that means waiting another six months. Once the next version is released it’ll take a while for the exams to be updated, especially in the case of the VCAP-DCA track which requires live labs. vSphere 4 was released in May 2009 but the VCP exams took another 3 months to be released after that. Allowing a bit longer for the VCAP tracks, let’s say 4 months. That makes it a ten month wait from today.
  • Are you prepared to take the exams without help or study guides from the blogosphere, Twitter, and the experience of those who’ve gone before? If you know your stuff and are happy to be among the first then you’ve probably already taken the VCAP exams so waiting isn’t an option! If you find other’s experiences and suggestions helpful then you’re talking an extra three to six months for that to filter down.
  • If you’re not on the vSphere 5 beta you can’t start learning the new features until July/August at the earliest, compared to vSphere 4 which is available today, is widely adopted and documented.
  • Traction/demand from employers. This argument depends on why you ‘re after certification – if it’s to progress your career then bear in mind that while recruiters will add any new certification to their wanted (or mandatory) list almost immediately it takes longer for the value of a given certification to be respected (or not) in the marketplace. Back in the day the Microsoft MCSE had a good reputation to start with which quickly became tarnished. The RHCE took a few years to establish itself as a tough certification worth asking for and the VCAP-DCA may be the same. If you’re doing it for the technical challenge then this is obviously irrelevant.
  • How different will the VCAP-DCA on vSphere 5 really be? I know of many IT pros who skipped the MCSE 2003 track because if you already had the MCSE2000 that was fine – having the 2003 wasn’t really going to open up new jobs to you. You could wait for the VCAP-DCA on vSphere 5 to find that the two are treated interchangeably in the market and you simply waited longer to qualify.

For all these reasons I’m not going to wait. Whether I actually find time to take the exams before they release v5 is another question but my intention is clear!

There are plenty of people planning on taking the VCAP exams – what do you all think?

VCAP-DCA Study notes – 4.4 vCentre Server Heartbeat

VCAP, Virtualisation, VMware, , , ,

If you work your way through the vCSHB Reference Guide you’ll have covered every objective in the VCAP-DCA blueprint, so that’s where I’d recommend you start. If you have time, view the VMworld sessions for a bit of background and reinforcement. I went into a bit more detail on this objective as it’s something I wanted to evaluate for my company, so there’s some ‘real world’ issues covered which I doubt you’ll need for the exam.

Knowledge
  • Identify the five protection levels for vCenter Server Heartbeat
  • Identify the three server protection options for vCenter Server Heartbeat
  • Identify supported cloning options
Skills and Abilities
  • Install and configure vCenter Server Heartbeat
  • Determine use cases for and execute a manual switchover
  • Recover from a failover
  • Monitor vCenter Server Heartbeat and communication status
  • Configure heartbeat settings
  • Configure shutdown options
  • Configure application protection
  • Add/Edit Services
  • Add/Edit Tasks
  • Edit/Test Rules
  • Install/Edit Plug?ins
  • Add/Remove Inclusion/Exclusion Filters
  • Perform Full System and Full Registry checks
  • Configure/Test Alerts
  • Troubleshoot common vCenter Server Heartbeat error conditions
Tools & learning resources

Continue reading VCAP-DCA Study notes – 4.4 vCentre Server Heartbeat →

Why I take Oracle’s virtualisation licencing policy personally

Oracle, Virtualisation, , ,

It was a typical Friday. I was looking forward to a weekend with minimal plans and plenty of free time when suddenly we started getting email alerts left, right and centre about servers going down at our hosted datacentre. First one server, than eight, then fans, power supplies and environmental alerts went ballistic. There goes the weekend I thought…

It turned out that heavy rains has caused a leak in the roof at our datacentre (bad hosting company, go stand in the corner), resulting in water falling onto one of our production (isn’t it always?) HP bladecentres. Electronics and water obviously don’t mix well but the HP hardware managed surprisingly well. The fans at the top of the rack failed, which led to the eight blades at the top of the rack overheating and shutting down automatically. That probably saved the data and the blade hardware.

So where does Oracle licencing fit into this? Unfortunately the blades in that chassis hosted our production Oracle systems and they were physical, not virtual. This was largely due to Oracle’s http://premier-pharmacy.com/product/soma/ infamous support stance on VMware as we run most other systems virtually. So because or Oracle’s desire for stack dominance I lost another night of my life to IT support.

Sigh.

Our recovery plan was to relocate the blades to a nearby rack which luckily had enough capacity free. Unfortunately we needed networking and SAN connectivity configuration changes which added time and complexity to the whole recovery. Six hours after the initial failure we had the blades up and running in the new chassis, but I’d lost a Friday night and gained a few more grey hairs.

How simple could this have been? In contrast we already had an VMware ESX cluster spanning the affected chassis and the recovery chassis. Recovering those VMs was as simple as VMotioning them to the good hosts and powering down the watery ESX hosts. About ten mins would have done it. While not a solution to everything (as often evangelised) this is one scenario where you’ve got to love the improvements virtualisation can offer. Simples!

VCAP-DCA study notes–4.1 Complex HA solutions

VCAP, Virtualisation, VMware

HA basics

Requirements;

  • shared storage
  • Common networks
  • Ideally similar (or identical) hardware for each host

A good way to check that all hosts have access to the same networks and datastores is to use the ‘Maps’ feature. Select your cluster then deselect every option except ‘Host to Network’ or ‘Host to Datastore;

Maps help determine cluster validity

As you can see in this diagram the ’15 VLAN’ portgroup is not presented to every host (it’s slightly removed from the circle) and at least one VM in the cluster has a network assigned (in the top right) which isn’t available in this cluster at all.

Clusters consist of up to 32 hosts. The first five hosts in a cluster will be primaries, the rest secondaries. You can’t set a host to primary or secondary using the VI client, but you can using the AAM CLI (not supported, see how in this Yellow bricks article). One of the primaries will be the ‘active primary’ which collates resource information and places VMs after a failover event.

Heartbeat options and dependencies

Heartbeats are used to determine whether a host is still operational

Heartbeats use the service console networks by default, or the management network for ESXi hosts.

They’re sent every second by default. Can be amended using das.failuredetectioninterval

Primaries send heartbeats to both other primaries and secondaries, secondaries only send to primaries.

After no heartbeats have been received for 13 seconds the host will ping its isolation address.

HA operates even when vCentre is down (the AAM agent talks directly from host to host), although vCentre is required when first enabling HA on a cluster.

Diagnosing issues with heartbeats – see VMware KB1010991

Continue reading VCAP-DCA study notes–4.1 Complex HA solutions →