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Storage, Replication, and Backups

Level 13

This is the fourth post of my series on hyperconverged infrastructure (HCI) architectural design and decision-making. For my money, the differences between these diverse systems is a function of the storage involved in the design. On the compute side, these environments use x86 and a hypervisor to create a cluster of hosts to support a virtual machine environment. Beyond some nuances in the hardware-based models, networking tends toward a similar approach in each. But often, the storage infrastructure is a differentiator.

Back in 2008, LeftHand Networks (later acquired by HPE) introduced the concept of a virtual storage appliance. In this model, the storage would reside within the ESX servers in the cluster, become aggregated as a virtual iSCSI SAN, and allow for redundancy through the nodes. Should an ESX host crash, with the standard function of the VMs rebooting on a different host in the cluster, the storage would allow for consistency regardless. By today’s standards, it’s not at all inelegant, but lacks some of the functionality of, for example, vSAN. VMware vSAN follows a similar model, but can also incorporate deduplication, hybrid or all solid-state disc, and compression. To me, vSAN used in vSAN-ready nodes, also a component of Dell/EMC VxRail product, is a modernized version of what LeftHand brought to the table some 11 years ago. It’s a great model and eliminates the need for a company to build a virtualized infrastructure to purchase a more traditional SAN/NAS infrastructure to connect the virtualized environment. Cost savings and management make this more cost-effective.

Other companies in the space have leveraged the server-based storage model. The two that spring most rapidly to mind are Nutanix and Simplivity, who have built solutions based on packaged single SKUed boxes built around a similar model. Of course, the way to manage the environments are different, but support the goal of managing a virtual landscape with some aspects of differentiation (Nutanix supports their hypervisor, Acropolis, which nobody else does). From a hardware perspective, the concept of packaged equipment sized to manage a particular environment is practically the same: x86 servers run the hypervisor, with storage internal to each node of the cluster.

I’ve talked previously about some of the scalability issues that may or may not affect end users, so I won’t go deeper into it here. Feel free to check out some of my previous posts about cluster scalability issues causing consternation about growth.

But storage issues are still key, regardless of the platform you choose. I believe it’s one of only two or three issues of primary concern. While compression, deduplication, and the efficiency of how SSD is incorporated are key to using storage, there’s more. One of the keys to backing up the data in a major use-case for HCI, the hub-and-spoke approach in which the HCI sits on the periphery and a more centralized data center resides as the hub, is the replication of all changed data from the remote to the hub, with storage awareness.

I feel many of the implementations I’ve been part of have had the HCI as ROBO (remote office/back office), VDI, or a key application role and require a forward-thinking approach to the backup of these datasets. If you, as the decision-maker, value that piece as well, look at how the new infrastructure would handle the data and be able to replicate it (hopefully with no performance impact to the system) so all data is easily recoverable.

When I enter these conversations, if the customer doesn’t concern themselves with backup or security from the ground-up, mistakes are being made. I try to emphasize this is likely the key consideration from the beginning. 

20 Comments

There's a load of brainwork in there--thank you for sharing your thoughts on the topic.

Copying & pasting the text into SMOG produced some fun analyses of the readability of that technical information:  http://www.readabilityformulas.com/freetests/six-readability-formulas.php

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I'm happy my comprehension was 100%.  Thwack members are no slouches--and neither are contributors like you, mbleib​ !

Level 13

I've never seen that scaling before. Very interesting. Does it mean that I write at a college entry level? I was actually a literature major. I may not be all that techy, but I do pride myself on my writing, wordchoice and grammar.

Thanks, rschroeder​ for the feedback. Much appreciated.

Yes, the results suggest what you've shared would require a person to have college entry level reading skills to understand it.

The ability to easily read and understand text is measured through the ratio of sentences, sentence length (words per sentence) and how many sentences contain words with three or more syllables.

The shorter the sentences, and the fewer the sentences, combined with sentences containing more three-syllable words, the greater the need for more education before a reader can understand that writing.

The ratings equate to years of education.  Text that is easily read and understand is rated with a lower number.

To write so that the most people will be able to read one's text, one would use the fewest amount of long words, and, at the same time, accept that longer phrases might be required to transfer the same ideas.

A ranking of "1" means it could be read and understood by anyone with a First Grade education.

On the other hand, it's possible to create documentation that is difficult to read, and while it may suite one's own skills, it could prevent others from seeing the meaning.  And that may not be one's intent.

Ranks 1-12 equate to the U.S. public education system grades First through Twelfth.  Ranks 13-16 mean a college / undergraduate level of education is required to make sense of the writing.

Scores of 17-18 suggest the work may not be understood by readers without a Master's degree.

Ranks of 19 and higher predict only readers in a Ph.D. program (or beyond) may be able to make sense of what one has written.   And that's not good if you want people to like and know what you wrote.

Of course, there are exceptions, but this simple math can help one predict how will written topics may succeed by reaching more people.

I try to remember to create text that is easily readable by the people I hope will be exposed to my writing, but I have to try to remember--it doesn't always come naturally.

Level 13

This is quite interesting. I do try consistently to give thought to who my audience is, and not overload them with vocabulary that's not jargony, or even too flowery. So, this kind of validation is really helpful to me. Once again, thank you.

Level 13

I've never done very well on those reading scale things either.  My first draft is always too high and it takes several cuts to get it down to where it's acceptable.

Level 13

Good post by the way mbleib​.  Thanks for the series.  Definitely a lot that goes in to HCI and a lot of variables that you need to take into account to make sure that what you end up selecting is actually optimal for your environment.

Level 13

I've seen way too many of these implementations go awry because the variables hadn't been truly considered. I appreciate the feedback, df112

Level 14

Thanks for the article.  There seems to be a lot of chatter about HCI these days. 

Level 13

Couldn't agree more. Plus, as an architect, our role is to make sure that our salespeople don't send the customer in a potentially unsuccessful project because they've sold by popularity rather than functionality

I'm in the same boat as you, df112 .  Seeing the readability index for my writing helps me be more reader-friendly in current and future tasks.  The index can help me recognize sometimes I'm verbose merely because I want to seem smarter than I might be.  I don't needs that kind of ego stroking showing up in my writing; when I see it I try to fix it.

Level 13

I've been accused of being pedantic before, and rightly so! I make concerted effort to not use the 10$ words, when a more accessible one is just as accurate. That being said, when I can economically use the ideal word, even if it is more rarified than it needs to be, I'll still choose that one, but only out of necessity. I love language.

I like the way you think.  I, too, love a good turn of phrase.

Level 12

Something that scares me is people who have never tried restoring from a backup. I make a point to do this at least once every two months in a dev environment, just to make sure that everything is working properly.

The test has failed EVERY TIME I HAVE DONE THIS AT A NEW JOB!

MVP
MVP

Thanks for the article.

Level 15

Thanks for the write up

MVP
MVP

What bites is when you go to rebuild a server and want a full restore only to find out the backup team had been ignoring errors for a long period of time and you don't have a viable backup anymore......  I miss the days of a weekly full backup with daily incrementals and the ability to request a full backup before doing any major work on a system.

Level 13

Well, it's the same on all platforms. If you don't test it, you cannot rely on restoring it.  Spot, full, DR exercise, etc. are critical to ensuring that the backups are valid. Remember: Snapshots or Replication alone do NOT qualify as backups. They can be considered as part of the scenario, but never will they be the whole. I spend a lot of time working on this with customers. The backup on this HCI scenario is a big conversation, but in IT as a whole, I've spent much time with customers architecting and aiding to build a true DR strategy.

Level 11

Thanks for the article.

Level 13

Good article.  We have dipped our toes in the HCI environment.

Level 13

Thanks for the article

About the Author
Hi, I'm Matt Leib. I'm an old dude, with years on the customer side, years on the vendor side, and now, years on the channel side. Exist as a Pre-Sales Solutions Architect in the channel space. I specialize in virtualization, orchestration, storage and cloud. On my personal blog, I talk about anything from baseball and music to most technical things I enjoy including personal and enterprise tech. For the last few years, I've been a Tech Field Day delegate, and a blogger on Thwack's Geek Speak as well as a personal blog site at http://Virtuallytiedtomydesktop.wordpress.com . Always learning, growing (though sometimes, that's the waistline) and striving to be as good as I can. I also like to sing, play guitar, and am a rabid Cubs and Blackhawks fan. I live in Evanston, IL, a suburb of Chicago, also grew up here. I work for Connection Enterprise Solutions, in a strategic solutions role, speaking to C Level on Corporate IT Initiatives