I’ll keep this post really brief, but you could blow me down with a feather when I found out that it is possible to get completely free and official practice exam voucher codes from Kryterion!
The only proviso is that you need to already have passed at least one exam. It seems that one key benefit to being AWS certified is that they will provide you with a free exam voucher code for the next exam you do, which could be used towards either Associate or Professional level exams! How great is that?
For me personally, the practice exams are a brilliant (if not the best) way to prepare for the AWS exams. I always use them in the last couple of days as a way to check my progress, build confidence before the exams, and weed out / fill in any gaps in my knowledge.
So… how do I get these free official AWS practice exam voucher codes then?
It’s very simple! To get the free official practice exam voucher code, follow the steps below!
Log into your certification account.
Click Redeem My Benefits.
Select one of the lines from an existing exam and click Claim Benefit.
It will then provide you with an exam voucher code for free!
Then just go to Schedule and Manage Your Exams.
Click Register for an Exam.
Expand +AWS Practice Exams.
Add your preferred test practice to your basket.
Enter your code into the Coupon / Voucher Code field.
You’re done! Now just click Launch!
There we go, easy peasy! Even better, this is repeatable for as many exams as you have done, so each time you pass an exam, you will get another voucher!
There is a certain amount of irony that the last post I did was on re-skilling, as this is the precise reason that it has taken me about 6 weeks to get around to posting this deck from our session at the McVMUG (Scottish VMUG)! I have spent all my time studying for my Microsoft Azure Architect exam (70-534)! Anyway, enough about that, I will cover it in a future post!
Last month, Chris Porter and I did a presentation at the Scottish VMUG (aka McVMUG) on AWS for VMware admins; a simple beginners guide with a few gotchas and tips we’ve picked up along our journeys to the public cloud.
The results of our mini survey were very similar to those of the recent London VMUG, in that most people had little or no AWS experience, but several were planning to do any AWS certs in the next 12 months, though notably less than half this time round.
After the McVMUG I was fortune enough to be able to go and spend a couple of days visiting family in my hometown of Oban. Here are a couple of cheeky snaps I managed to grab on the stunning train, if grey, journey to the West Highlands (between watching Azure study videos!). There also follows a wee pano from the hill behind my teenage home, looking out across Oban bay towards the island of Kerrera. Definitely enough to make me homesick!
The subject matter of this post is a startup of sorts and was triggered by a conversation I had with an industry veteran a few months back. By veteran of course, I mean an old bugger! 😉
It is an entity which begins its journey sourcing a target market in the tech industry and spends day and night pursuing that market to the best of its ability.
It brings in resources to help meet the key requirements of the target market; some of those resources are costly, and others not so much.
Occasionally it hits a bump in the road with funding and potentially needs to find other sources of investment, and may go through several rounds of funding over the course of a number of years. Eventually it gets to a point where the product is of a decent quality and market value.
Then it does a market analysis and discovers that the market has shifted and if the entity does not pivot or indeed re-skill, they will become irrelevant within a few short years.
I am of course talking about the career of an IT professional.
Though I may be slightly exaggerating on the becoming irrelevant quite so fast, we certainly all made the choice to follow a career in one of the fastest moving industries on the planet. We have no choice but to continue to develop and maintain our knowledge, in order to keep driving our careers forward.
As a self-confessed virtual server hugger with a penchant for maintaining a pretty reasonable home lab, I enjoy understanding the detailed elements of a technology, how they interact, and acknowledging where the potential pitfalls are. The cloud, however, is largely obfuscated in this respect; to the point where many cloud companies will not even divulge the location of their data centres, never mind the equipment inside them and configuration thereof!
That said, those of you with a keen eye may have noticed a shift in my twitter stream in the past year or so, with subjects tending towards a more public cloudy outlook… Talking to a huge range of customers in various verticals on a regular basis, it feels to me that a great many organisations are right on the tipping point between their current on-premises / dedicated managed services deployment models, and full public cloud adoption (or at the very least hybrid!).
It’s hard to believe that companies like AWS have actually been living and breathing public cloud for over ten years already; that’s almost as long as my entire career! In that time they have grown from niche players selling a bit of object storage, to the Behemoth-aaS they are today. To a greater or lesser extent (and for better or worse!), they are now the yardstick upon which many cloud and non-cloud services are measured. This is also particularly the case when it comes to cost, much to the chagrin of many across the industry!
To me, this feels like the optimum time for engineers and architects across our industry (most definitely including myself) to fully embrace public and hybrid cloud design patterns. My development has pivoted predominantly towards technologies which are either native to, or which support public cloud solutions. Between family commitments, work, etc, we have precious little time to spend in personal development, so we need to spend it where we think we will get the most ROI!
So what have I been doing?
Instead of messing about with my vSphere lab of an evening, I have spent recent months working towards certified status in AWS, Azure, and soon, GCP. This has really been an eye opener for me around the possibilities of designs which can be achieved on the current public cloud platforms; never mind the huge quantity of features these players are likely to release in the coming 12 months, or the many more after that.
Don’t get me wrong, of course, everything is not perfect in the land of milk and honey! I have learned as much in these past months about workloads and solutions which are NOT appropriate for the public cloud, as I have about solutions which are! Indeed, I have recently produced a series of posts covering some of the more interesting AWS gotchas, and some potential workarounds for them. I will be following up with something similar for Azure in the coming months.
Taking AWS as an example, something which strikes me is that many of the features are not 100% perfect and don’t have every feature and nerd knob under the sun available. Most seem to have been designed to meet the 80/20 rule and are generally good enough to meet the majority of design requirements more than adequately. If you want to meet a corner use case or a very specific requirement, then maybe you need to go beyond native public cloud tooling.
Anyhow, that’s enough rambling from me… By no means does this kind of pivot imply that everything we as infrastructure folks have learned to date has been wasted. Indeed I personally have no intention to drop “on premises” skills and stop designing managed dedicated solutions. For the foreseeable future there will likely be a huge number of appropriate use cases, but in many, if not most cases I am being engaged to look at new solutions with a publicly cloudy mindset!
I write this whilst sitting in an airport lounge, having been disembarked from my plane due to a technical fault. I don’t really begrudge the airline in question; it was a plumbing issue! This is a physical failure of the aircraft in question and just one of those things (unless I find out later they didn’t do the appropriate preventative maintenance of course)! Sometimes failures just happen and I would far rather it was just a plumbing issue, not an engine issue!
What is not excusable, however, is if the downtime is easily preventable; for example, if you are designing a solution which has no resilience!
This is obviously more common with small and medium sized businesses, but even large organisations can be guilty of it! I have had many conversations in the past with companies who have architected their solutions with significant single points of failure. More often than not, this is due to the cost of providing an HA stack. I fully appreciate that most IT departments are not swimming in cash, but there are many ways around a budgetary constraint and still provide more highly available, or at least “Disaster Resistant” solutions, especially in the cloud!
Now obviously there is High Availability (typically within a single region or Data Centre), and Disaster Recovery (across DCs or regions). An ideal solution would achieve both, but for many organisations it can be a choice between one and the other!
Budgets are tight, what can we do?
Typically HA can be provided at either the application level (preferred), or if not, then at the infrastructure level. Many solutions to improvise availability are relatively simple and inexpensive. For example:
Building on a public cloud platform (and assuming that the application supports load balancing), why not test running twice as many instances with half the specification each? In most cases, unless there are significant storage quantities in each instance, the cost of scaling out this way is minimal.
If there is a single instance, split it out into two instances, immediately doubling your availability. If there are two instances, what about splitting into 4? The impact of a node loss is then only 25% of the overall throughput capacity for the application, and can even bring down the cost of HA for applications where the +1 in N+1 is expensive!
Again in cloud, if there are more than two availability zones in a region (e.g. on AWS), then take advantage of them! If an application can handle 2 AZs, then the latency of adding a third shouldn’t make much, if any difference, and costs will only increase slightly with a small amount of extra inter-AZ bandwidth or per-AZ services (e.g NAT gateways).
Again, in this scenario the loss of an AZ will only take out 33% of the application servers, not 50%, so it is possible to reduce the number of servers which are effectively there for failover only.
If you can’t afford to run an application as multi-AZ or multi-node, consider putting it in an auto-scaling group or scale-set with a minimum and maximum of 1 server. That way if an outage occurs or int he case of AWS, an entire AZ goes down, an instance will automatically be regenerated in an alternative AZ.
What if my app doesn’t like load balancers?
If you have an application which cannot be load balanced, you probably shouldn’t be thinking about running it in the cloud (not if you have any serious availability requirements anyway!). It amazes me how many business critical applications and services are still running in single servers all over the world!
If your organisation is dead set on using cloud for a SPoF app, then making it as ephemeral as possible can help. Start by splitting the DBs from the apps, as these can almost always be made HA by some means (e.g. master/slave replication, mirroring, log shipping, etc). Failover nodes also often don’t attract a license fee from many vendors (e.g. MS SQL), so always check your license documentation to see what you can achieve on the cheap.
Automate! If you can deploy application server(s) from a script, even if the worst happens, the application can be redeployed very quickly, in a consistent fashion.
The trend at the moment is moving towards a more agile deployment process and automated CI/CD pipelines. This enables companies to recover from an outage by rebuilding their environments and redeploying code rapidly (as long as they have a replica of the data or a highly available datastore!).
If it’s not possible to script or image the code deployment, then taking regular backups (and snapshots where possible) of application servers, and testing them often is an option! If you don’t want to go through the inflexible, unreliable and painful nightmare of doing system state restores, then take image-based backups (supported by the vast majority of backup vendors nowadays). Perhaps even syncing of application data to a warm standby server which can be brought online reasonably swiftly, or even use an inexpensive DR service such as Azure Site Recovery, to provide an avenue of last resort!
If maybe cloud isn’t the best place to locate your application, then provide HA at the infrastructure layer by utilising the HA features of your favourite hypervisor!
For example, VMware vSphere will have an instance back up and running within a minute or two of the failure of a host using the vSphere HA feature (which comes with every edition except Essentials!). On the assumption/risk that the power cycle does not corrupt OS, applications or data, you minimise exposure to hardware outages.
If the budget is not enough to buy shared storage and all VMs are running on local storage in the hypervisor hosts (I have seen this more than you might imagine!), then consider using something like vSphere Replication or Hyper-V Replicas to copy at least one of each critical VM role to another host, and if there are multiple instances, then spread them around the hosts.
Finally, make sure whatever happens there is some form of DR, even if it is no more than a holding page or application notification and a replica or off-site backup of critical data! Customers and users would rather see something telling them that you’re working to resolve the problem, than getting a spinning wheel and a timeout! If you can provide something which is of limited functionality or performance, then it’s better than nothing!
TLDR; High Availability on a Budget
There are a million and one ways to provide more highly available applications; these are just a few. The point is that providing highly available applications is not as expensive as you might initially think.
With a bit of elbow grease, a bit of scripting and regular testing, even on the smallest budgets you can cobble together more highly available solutions for even the crummiest applications! 🙂