VCP6-DCV Delta Exam (2V0-621D) Study Guide and Exam Experience

Having successfully completed the VCP6-DCV Delta Exam (2V0-621D) this week, I thought it would be worthwhile jotting down a few thoughts on the exam, and noting the resources I used to prepare for it.

I’ve previously completed the VCP3, VCP4 and VCP5 “DCV” exams, however being specifically a delta exam, this one was a little different. The exam primarily covers the differences between vSphere 5 and vSphere 6, with a handful of seemingly more general questions.

For summary impressions of the exam (i.e. the TLDR), jump to the end of this article! 🙂

Preparation
I used the following resources in prep for the exam:

homelab

The Exam
The exam itself was different to any previous VCP exam I’ve done. I would say that because the scope of the exam was much narrower, the depth of the questions seemed to me to be significantly more, with a few really tricky ones thrown in there.

Over all if I was to do it again (and when it comes time to do the VCP7 in a few years) I would probably just do the full VCP exam, rather than the delta. That way you can be sure of a decent number of the easy peasy questions which will probably be on stuff you’ve been doing for years, as well as the new stuff you may not know quite as well.

Obviously having not done the full VCP6 exam I can’t say this for sure, but I would say it’s a pretty good bet.

What a Fan-tash-tic result for Movember! Thank you!

This is just a quick post to thank you, everyone, for your amazing support of my (let’s be honest, poor!) Movember efforts!

After 30 days and nights of itching, scratching, shaving, nicking, picking, scalping, cringing, splashing, screaming, yelping, remembering, laughing, grooming, combing and grimacing (from my wife when I gave her a kiss), we managed to raise a staggering £711!!!

http://mobro.co/alexgalbraith

My wife is grimacing even more now that I have shaved the tash, but told her I’m keeping the sideboards for at least a couple more weeks… 🙂

Anyway, I have said it before and I’ll say it again, thank you to everyone for your amazing generosity, it really blew away both my expectations and my original target of £200!!!

To say thank you, what else can I do but provide a smorgasbord (perhaps a cheese board?) of tashes for your consumption.

Thank you, everyone!

Where and why is my data growing?…

I’ve written recently about issues of data gravity and data inertia, and about how important analytics are to managing your data “stockpile”, but one thing I haven’t gone into is the constant challenge of actually understanding your data composition, i.e. what the hell am I actually storing?!

Looking back to my days as a Windows admin maintaining what for the time were some massive, multi-terabyte (ooer – it was 10 years ago to be fair), filers and shared document storage systems; we had little to tell us what the DNA of those file shares was, how much of it was documents and other business-related content, and how much of it was actually people storing their entire MP3 collections and “family photos” on their work shared drives (yes, 100% true!).

Back then our only method of combating these issues was to run TreeSize to see who was using most space, then do windows searches for specific file types and manually clear out the crud; an unenviable task which came across a few surprising finds I won’t go into just now (ooer for the second time)! The problem was that we just didn’t know what we had!

Ten years later I have spoken to customers who are consuming data at very significant rates, but don’t have a grip on where it’s all going…

With that in mind, I was really interested in what the chaps at Qumulo had come up with when they presented at SFD8 recently. As they said at the time, the management of storage is getting easier, but the management of data is getting very much harder! Their primary vision is therefore quite succinctly described as “Build visible data and make storage invisible”.

Their “Data Aware” scale-out NAS solution is based around providing near-realtime analytics on the metadata, and was designed to meet the requirements of the 600 companies and individuals they interviewed before they even came up with their idea!

The product is designed to be software only and subscription-based, though they also provide scale out physical 1u / 4u appliances as well. I guess the main concept there is “have it your way”; there are still plenty of customers out there who want to buy software solution which is pre-qualified and supported on specific hardware (which sounds like an oxymoron but each to their own I say)! Most of Qumulo’s customers today actually buy the appliances.

The coolest thing about their solution is definitely their unique file system (QSFS – Qumulo Scalable File System). It uses a very clever, proprietary method to track changes within the filesystem based on the aggregate of child attributes in the tree (see their SFD8 presentation for more info). As you then don’t need to necessarily walk the entire tree to get an answer to a query (it should be noted this would be one specifically catered for by Qumulo though). It can then present statistics based on those attributes in near-realtime.

Whiteboard Dude approves!

Whiteboard Dude approves!

I would have killed for this level and speed of insight back in my admin days, and frankly I have a few customers right now who would really benefit!

Taking this a step further, the analytics can also provide performance statistics based on file path and type, so for example it could show you where the hotspots are in your filesystem, and which clients are generating them.

Who's using my storage?

Who’s using my storage?

Stuff I would like to see in future versions (though I know they don’t chase the Service Provider market), would be things like the ability to present storage to more than one Active Directory domain, straight forward RBAC (Role Based Access Control) at the management layer, more of the standard data services you see from most vendors (the RFP tick box features). Being able to mix and match the physical appliance types would also be useful as you scale and your requirements change over time, but I guess if you need flexibility, go with the software-only solution.

At a non-feature level, it would be sensible if they could rename their aggregate terminology as I think it just confuses people (aggregates typically mean something else to most storage bods).

Capacity Visualisation

Capacity Visualisation

Overall though I think the Qumulo system is impressive, as are the founder’s credentials. Their CEO/CTO team of Peter Godman and Aaron Passey, with whom we had a good chinwag outside of the SFD8 arena, both played a big part in building the Isilon storage system. As an organisation they already regularly work with customers with over 10 billion files today and up to 4PB of storage.

If their system is capable of handling this kind of scalability having only come out of stealth 8 months ago, they’re definitely one to watch…

Further Reading
Some of the other SFD8 delegates have their own takes on the presentation we saw. Check them out here:

Dan Frith – Qumulo – Storage for people who care about their data

Scott D. Lowe – Data Awareness Is Increasingly Popular in the Storage Biz

Disclaimer/Disclosure: My flights, accommodation, meals, etc, at Storage Field Day 8 were provided by Tech Field Day, but there was no expectation or request for me to write about any of the vendors products or services and I was not compensated in any way for my time at the event.

 

NanoLab – Part 10 – Your NUCs are nice and cool, but what about your stick?

I have been running a variety of Intel NUC nodes in my vSphere homelab over the past 3 years now, including the D34010WYKH, DC3217IYE & DC53427HYE.

In that time I have unfortunately seen more than my fair share of USB drive failures and corruptions, generally with an error which looks something like this:

Error loading /k.b00
Fatal error: 33 (Inconsistent data)

 
These are not cheap and nasty, or freebie USB drives, so I would not normally expect to see this rate of failures. The error only occurs when you reboot the host, and the startup bombs out at the start of the hypervisor launch. I have often managed to recover the stick by copying back corrupted files from another instance, but generally I needed to rebuild and restore the image. An unnecessary pain in the rear!

The Root Cause
The NUC case can become quite warm during normal operation with or without the fans spinning up, and I have come to believe that the main reason for the corruptions is that the USB stick itself is getting too hot and therefore eventually failing. Having pulled a USB out from a recently shut down node, they are really quite hot to the touch. You don’t actually see the symptom / failure until a reboot because the ESXi image actually runs in memory, so is only loaded from the USB stick at boot time.

The Solution
As for the solution, it’s really quite simple. I purchased a number of 12cm (5 inch) USB 2.0 extender cables on eBay for just 99p each (including delivery!).

These keep the USB stick indirectly attached to the NUC chassis, and as such the heat does not transfer into the flash drive. Since doing this I have not seen any further issues with the corruptions. Job done!

Keeping things cool: USB extender on Intel NUC

Keeping things cool: USB extender on Intel NUC

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