VSAN – The spoken reality

Yesterday Maish and Christian had a nice little back and forth on their blogs about VSAN. Maish published a post titled “VSAN – The Unspoken Truth” which basically talks about how VSAN doesn’t fit blade environments, and how many enterprise environments adopted blade to get better density from a physical point of view. With that meaning increase the number of physical servers to the number of rack U(nits) consumed. Also there is the centralized management aspect of many of these blade solutions that is a major consideration according to Maish.

Christian countered this with a great article titled “VSAN – The Unspoken Future“. I very much agree with Christian’s vision. Christian’s point basically is that when virtualization was introduced IT started moving to blade infrastructures as that was a good fit for the environment they needed to build. Christian then explains how you can leverage for instance the SuperMicro Twin architecture to get a similar (high physical) density while using VSAN at the same time. (See my Twin posts here) However, the essence of the article is: “it shows us that Software Designed Data Center (SDDC) is not just about the software, it’s about how we think, manage AND design our back-end infrastructure.”

There are three aspects here in my opinion:

  • Density – the old physical servers vs rack units discussion.
  • Cost – investment in new equipment and (potential) licensing impact.
  • Operations – how do you manage your environment, will this change?

First of all, I would like to kill the whole density discussion. Do we really care how many physical servers you can fit in a rack? Do we really care you can fit 8 or maybe even 16 blades in 8U? Especially when you take in to consideration your storage system sitting next to it takes up another full rack. Than on top of that there is the impact density has in terms of power and cooling (hot spots). I mean if I can run 500 VMs on those 8 or 16 blades and that 20U storage system, is that better or worse than 500 VMs on 12 x 1U rack mounted with VSAN? I guess the answer to that one is simple: it depends… It all boils down the total cost of ownership and the return on investment. So lets stop looking at a simple metric like physical density as it doesn’t say much!

Before I forget… How often have we had those “eggs in a basket” discussions in the last two years? This was a huge debate 5 years back, in 2008/2009 did you really want to run 20 virtual machines on a physical host? What if that host failed? Those discussions are not as prevalent any longer for a good reason. Hardware improved, stability of the platforms increased, admins became more skilled and less mistakes are made… chances of hitting failures simply declined. Kind of like the old Microsoft blue screen of death joke, people probably still make the joke today but ask yourself how often does it happen?

Of course there is the cost impact. As Christian indicated, you may need to invest in new equipment… As people mentioned on twitter: so did we when we moved to a virtualized environment. And I would like to add: and we all know what that brought us. Yes there is a cost involved. The question is how do you balance this cost. Does it make sense to use a blade system even for VSAN when you can only have a couple of disks at this point in time? It means you need a lot of hosts, and also a lot of VSAN licenses (+maintenance costs). It may be smarter, from economical point of view, to invest in new equipment. Especially when you factor in operations…

Operations, indeed… what does it take / cost today to manage your environment “end to end”? Do you need specialized storage experts to operate your environment? Do you need to hire storage consultants to add more capacity? What about when things go bad, can you troubleshoot the environment by yourself? How about my compute layer, most blade environments offer centralized management for those 8 or 16 hosts. But can I reduce the number of physical hosts from 16 or 8 to for instance 5 with a slightly larger form factor? What would the management overhead be, if there is any? Each of these things need to be taken in to considerations and somehow quantified to compare.

Reality is that VSAN (and all other hyper-converged solutions) brings something new to the table, just like virtualization did years ago. These (hyper-converged) solutions are changing the way the game is played, so you better revise your play book!

VSAN and the AHCI controller (hint: not supported!)

I have seen multiple people reporting this already so I figured I would write a quick blog post. Several folks are going from Beta to GA release for VSAN and so far people have been very successful, except for those using disk controllers which are not on the HCL like the on-board AHCI controller. For whatever reason it appeared on the HCL for a short time during the beta, but it is not supported (and not listed) today. I have had similar issues in my lab, and as far as I am aware there is no workaround at the moment. The errors you will see appear in the various logfiles have the keywords: “APD”, “PDL”, “Path lost” or “NMP device <xyz> is blocked”.

Before you install / configure Virtual SAN I highly want to recommend validating the HCL: http://vmwa.re/vsanhcl (I figured I will need this URL a couple of times in the future so I created this nice short url)

Update: with 5.5 U2 it is reported AHCI works, however still not supported!

Essential Virtual SAN book, rough cut online now!

A couple of weeks back Eric Sloof broke the news about the book Cormac Hogan and I are working on: Essential Virtual SAN. As of this weekend the rough cut edition is (back) online again, and you can see some of the progress Cormac and I have been making over the last couple of months. As we speak we are working on the final chapters… so hopefully before the end of the month the rough cut should be complete!

Note that this is a rough cut and that means the book will go through tech review (by VSAN Architect Christos Karamanolis, and VMware Integration Engineer Paudie O’Riordan), than editing and a final review by Cormac and I before it will be published. So expect some changes throughout that whole cycle. Never the less, I think it is worth reading for those who have a Safari Online account:


Building a hyper-converged platform using VMware technology part 3

Considering some of the pricing details have been announced I figured I would write a part 3 of my “Building a hyper-converged platform using VMware technology” series (part 1 and part 2) Before everyone starts jumping in on the pricing details, I want to make sure people understand that I have absolutely no responsibilities whatsoever related to this subject, I am just the messenger in this case. In order to run through this exercise I figured I would take a popular SuperMicro configuration and ensure that the components used are certified by VMware.

I used the thinkmate website to get pricing details on the SuperMicro kit. Lets list the hardware first:

    • 4 hosts each with:
      -> Dual Six-Core Intel Xeon® CPU E5-2620 v2 2.10GHz 15MB Cache (80W)
      -> 128 GB (16GB PC3-14900 1866MHz DDR3 ECC Registered DIMM)
      -> 800GB Intel DC S3700 Series 2.5″ SATA 6.0Gb/s SSD (MLC)
      -> 5 x 1.0TB SAS 2.0 6.0Gb/s 7200RPM – 2.5″ – Seagate Constellation.2
      -> Intel 10-Gigabit Ethernet CNA X540-T2 (2x RJ-45)

The hardware is around $ 30081,-, this is without any discount. Just the online store price. Now the question is, what about Virtual SAN? You would need to license 8 sockets with Virtual SAN in this scenario, again this is the online store price without any discount:

  • $ 2495,- per socket = $ 19960,-

This makes the cost of the SuperMicro hardware including the Virtual SAN licenses for four nodes in this configuration roughly $ 50.041. (There is also the option to license Virtual SAN for View per user which is $ 50,-.) That is around $ 12600 per host including the VSAN licenses.

If you do not own vSphere licenses yet you will need to license vSphere itself as well, I would recommend Enterprise ( $ 2875,- per socket) as with VSAN you will automatically get Storage Policy Based Management and the Distributed Switch. Potentially, depending on your deployment type, you will also need vCenter Server. Standard license for vCenter Server is $ 4995,-. If you would include all VMware licenses the total combined would be: $ 78036,-. That is around 19600 per host including the VSAN and vSphere licenses. Not bad if you ask me,

I want to point out that I did not include Support and Maintenance costs. As this will depend on which type of support you require and what type of vSphere licenses you will have I felt there were too many variable to make a comparison. It should also be noted that many storage solutions come with very limited first year support… Before you do a comparison, make sure to look at what is included and what will need to be bought separately for proper support.

** disclaimer: Please run through these numbers yourself, and validate the HCL before purchasing any equipment. I cannot be held responsible for any pricing / quoting errors, hardware prices can vary from day to day and this is exercise was for educational purposes only! **

Rebuilding your Virtual SAN Lab? Wipe the disks first!

Are you ready to start rebuilding your Virtual SAN lab from beta builds to GA code, vSphere 5.5 U1? One thing I noticed is that the installer is extremely slow when there are Virtual SAN partitions on disk. It sits there at “VSAN: successfully initialized” for a long time and when you get to the “scanning disks” part it takes equally as long. Eventually I succeeded, but it just took a long time. Could be because I am running with an uncertified disk controller of course, either way if you are stuck in the following screen there is a simple solution.

Just wipe ALL disks first before doing the installation. I used the Gparted live ISO to wipe all my disks clean, just delete all partitions and select “apply”. Takes a couple of minutes, but saved me at least 30 minutes waiting during the installation.