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Welcome to Technology Short Take #34, my latest collection of links, articles, thoughts, and ideas from around the web, centered on key data center technologies. Enjoy!


  • Henry Louwers has a nice write-up on some of the design considerations that go into selecting a Citrix NetScaler solution.
  • Scott Hogg explores jumbo frames and their benefits/drawbacks in a clear and concise manner. It’s worth reading if you aren’t familiar with jumbo frames and some of the considerations around their use.
  • The networking “old guard” likes to talk about how x86 servers and virtualization create network bottlenecks due to performance concerns, but as Ivan points out in this post, it’s rapidly becoming—or has already become—a non-issue. (By the way, if you’re not already reading all of Ivan’s content, you need to be. Seriously.)
  • Greg Ferro, aka EtherealMind, has a great series of articles on overlay networking (a component technology used in a number of network virtualization solutions). Greg starts out with a quick look at the value prop for overlay networking. In addition to highlighting one key value of overlay networking—that decoupling the logical network from the physical network enables more rapid change and innovation—Greg also establishes that overlay networking is not new. Greg continues with a more detailed look at how overlay networking works. Finally, Greg takes a look at whether overlay networking and the physical network should be integrated; he arrives at the conclusion that integrating the two is likely to be unsuccessful given the history of such attempts in the past.
  • Terry Slattery ruminates on the power of creating (and using) the right abstraction in networking. The value of the “right abstraction” has come up a number of times; it was a featured discussion point of Martin Casado’s talk at the OpenStack Summit in Portland in April, and takes center stage in a recent post over at Network Heresy.
  • Here’s a decent two-part series about running Vyatta on VMware Workstation (part 1 and part 2).
  • Could we use OpenFlow to build better internet exchanges? Here’s one idea.



I have nothing to share this time around, but I’ll keep watch for content to include in future Technology Short Takes.

Cloud Computing/Cloud Management

  • Tom Fojta takes a look at integrating vCloud Automation Center (vCAC) with vCloud Director in this post. (By the way, congrats to Tom on becoming the first VCDX-Cloud!)
  • In case you missed it, here’s the recording for the #vBrownBag session with Jon Harris on vCAC. (I had the opportunity to hear Jon speak about his employer’s vCAC deployment and some of the lessons learned at a recent New Mexico VMUG meeting.)

Operating Systems/Applications


  • Rawlinson Rivera starts to address a lack of available information about Virsto in the first of a series of posts on VMware Virsto. This initial post provides an introduction to Virsto; future posts will provide more in-depth technical details (which is what I’m really looking forward to getting).
  • Nigel Poulton talks a bit about target driven zoning, something I’ve mentioned before on this site. For more information on target driven zoning (also referred to as peer zoning), also be sure to check out Erik Smith’s blog.
  • Now that he’s had some time to come up to speed in his new role, Frank Denneman has started a great series on the basic elements of PernixData’s Flash Virtualization Platform (FVP). You can read part 1 here and part 2 here. I’m looking forward to future parts in this series.
  • I’d often wondered this myself, and now Cormac Hogan has the answer: why is uploading files to VMFS so slow? Good information.


It’s time to wrap up now, or this Technology Short Take is going to turn into a Technology Long Take. Anyway, I hope you found something useful in this little collection. If you have any feedback or suggestions for improvement for future posts, feel free to speak up in the comments below.

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About a year ago, I posted a look at my planned projects for 2012. Now, a year later, it’s time to review my progress (or lack thereof) and measure myself on how well I did (or didn’t) do on those projects.

First, let’s review the original project list:

  1. Learn to script in Perl.
  2. Learn to speak German.
  3. Become more familiar with Xen (and Open vSwitch and OpenStack).
  4. Pursue CCNP.

In my late June mid-year project update, I dropped the Perl scripting project simply because I had no practical applications driving the use of Perl. So, with that in mind, how did I do?

  1. Learn to speak German: Although I won’t say that I’ve actually learned to speak German, I have made some progress here. It’s not nearly the progress that I wanted to make, though—I wanted to be much farther along than I am. Grade: D

  2. Become more familiar with Xen, OVS, OpenStack: In retrospect, this project was overly broad, and therefore has mixed results. I ended up ditching Xen in favor of KVM, and made decent progress on that front. My work with Open vSwitch (OVS) was pretty good, probably the best out of the group. I still have quite a way to go with OpenStack, but I feel that time spent with KVM, OVS, and Libvirt helped build solid fundamentals for future progress. Grade: B

  3. Pursue CCNP: As I mentioned in the mid-year update, my goal was never to actually achieve CCNP this year, but simply to make progress. Regardless, my progress was abysmal. Grade: F

  4. Learn to work with Puppet: Not on my original project list, this is something that I nevertheless spent a fair amount of time pursuing. I’m not an expert (not anywhere close), but I feel like I did make reasonable progress. Grade: C

In summary: not very good!

So, what can I learn from these results?

  • First, the synergy of the projects really does make a difference. As readers noted in the comments on my original 2012 projects list, my choice of projects wasn’t synergistic, and this hampered efforts. Key takeaway: listen more closely to the advice of others!
  • Projects need to be more tightly defined. The “learn Xen, OVS, OpenStack” project was simply too broad, and encompassed too many different components. As a result, progress was mixed.
  • There are still some fundamental building blocks that I personally need to shore up. For example, my work with KVM, OVS, Libvirt, and Puppet exposed some gaps in my base Linux knowledge, and this is reflected in my progress.

In a (near-)future post, I’ll incorporate the progress on my 2012 projects and the key takeaways into my list of 2013 projects. Until then, I welcome any feedback or thoughts in the comments below.

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Welcome to Technology Short Take #27! This is my usual collection of links, thoughts, rants, and ideas about data center-related technologies. Here’s hoping you find something useful!


  • If you’re interested in learning more about OpenFlow and software-defined networking but need to do this on a shoestring budget in your home lab, a number of guides have been written to help out. I haven’t personally used any of these guides yet, but I’m working my way in that direction. (I needed to fill in some other knowledge gaps first.) First up is Brent Salisbury’s how to build an SDN lab without needing OpenFlow hardware. Brent is creating some fantastic content that I’ve found extremely useful. His earlier post on getting started with OpenFlow and Open vSwitch tutorial lab is also quite good. Another good resource is Dan Hersey’s guide to building an SDN-based private cloud in an hour. I encourage you to have a look at these posts if you’re at all interested in any of these technologies.
  • Bruce Davie and Martin Casado (with Nicira, now part of VMware) have written a post comparing the VXLAN and STT tunneling protocols. Not unsurprisingly, one of the key advantages of STT that’s highlighted is its improved performance due to TSO support in NIC hardware. VXLAN, on the other hand, is seeing broader adoption across multiple vendors. There’s no mention of NVGRE (or just plain GRE).
  • Related to the bare metal provisioning work (see below under “Servers/Hardware”), Mirantis also detailed some bare-metal networking stuff they’ve done for OpenStack in relation to the use of bare metal nodes.


  • Mirantis published an article discussing a framework they built for bare-metal provisioning with OpenStack that allows OpenStack to place workloads onto bare-metal nodes instead of onto a hypervisor. It’s interesting work, but unfortunately it looks like this work won’t be returned to the community (it was developed for one or more of their clients). There are also a few follow-up posts, such as this one on placement control and multi-tenancy isolation and this one on preparing images for bare metal nodes. Also see the “Networking” section above for a related post on the networking aspects involved.


I don’t have anything for this area this time around, but I’ll stay alert for articles to add next time. Feel free to share something in the comments!

Cloud Computing/Cloud Management

  • I might have mentioned this before, but Ken Pepple’s OpenStack Folsom architecture post is just awesome. It’s well worth reading and reviewing in depth.
  • This OpenStack-on-Debian HOWTO is a bit older (and probably out of date), but it does give a decent overview of the components that are involved and—via the configuration—how they relate to each other. While the details for installing a current version of OpenStack are likely to be different now, you might still find this conceptually helpful.
  • These articles are a bit long in the tooth, but CSS Corp has a useful series of articles on bundling various Linux distributions for use with OpenStack: bundling CentOS, bundling CentOS with VNC, bundling Debian, and bundling OpenSUSE. It would be interesting to me to see how much of this, if any, could be automated with something like Puppet. If any enterprise Puppet experts want to give it a go, I’d be happy to publish a guest blog post for you with full details on how it’s done.
  • Much like there are some great “how to’s” on how to run an SDN lab (see the Networking section earlier), there are also some great write-ups on doing the same for OpenStack. For example, Cody Bunch published this article on running OpenStack Private Cloud on ESXi, and Brent Salisbury (there he is again!) posted an older guide to OpenStack Essex on Ubuntu on VirtualBox as well as a newer guide to OpenStack DevStack on Fusion.

Operating Systems/Applications


  • I don’t fully understand all the details involved, but this post on changes in block protocol scalability in Xen outlines what sounds like good progress in improving efficiency.
  • This article is a bit older, published at the start of October, but it talks about an interesting project (product?) by Qlogic called “Mt. Rainier.” (Stu Miniman of Wikibon has more information here as well.) Apparently, “Mt. Rainier” will allow customers to combine PCIe-based SSD storage inside servers into a “virtual SAN” (now there’s an original and not over-used term). The really interesting aspect, in my opinion, is the use of “Mt. Rainier” to create shared caches across servers. Is this the beginning of the data center fractal edge?


  • Big news in the QEMU world: In the QEMU 1.3 release, the QEMU-KVM and QEMU projects have been merged. Why is this important? It’s first necessary to understand the relationship between QEMU and KVM. KVM is the set of kernel modules that leverage hardware virtualization functionality inside Intel and AMD CPUs, and it makes possible the virtualization of closed-source operating systems like Windows. QEMU, on the other hand, is needed to emulate everything else that a VM needs: networking, storage, USB, keyboard, mouse, etc. Both KVM and QEMU are needed for a full virtualization solution. Until the 1.3 release, QEMU (without hardware acceleration via KVM) was one branch, and QEMU-KVM (with KVM hardware acceleration) was a separate branch. The QEMU 1.3 release completes an effort to merge both efforts into a single development tree.
  • The merge of QEMU and QEMU-KVM isn’t the only cool thing happening with QEMU; also included in the 1.3 release is GlusterFS integration. This integration dramatically improves GlusterFS performance by allowing QEMU’s block layer to communicate directly with the Gluster backend without going through the userspace FUSE components.
  • Erik Scholten of VMGuru.nl has posted a good hypervisor feature comparison document. It includes RHEV 3.1 in the comparison, even though RHEV 3.1 wasn’t released (was still in beta) at the time the comparison was written.
  • Speaking of RHEV: apparently RHEV 3.1 was released yesterday (Wednesday, December 4, 2012), although I haven’t been able to find any sort of official press release or announcement.
  • Debunking an argument I’ve heard quite a bit is this article by Frank Denneman on using SIOC with multiple datastores backed by a single pool of disks.
  • Need to compact a virtual hard disk in Windows 8/Windows Server 2012? Ben Armstrong shows how here.
  • I enjoyed this article by Josh Townsend on using SUSE Studio and HAProxy to create a (free) open source load balancing solution for VMware View.

That’s it for this time around; no need to overwhelm you with too much information! Besides, I have to keep a few items around for Technology Short Take #28…

As always, comments, thoughts, rants, or corrections are welcome below.

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Welcome to Technology Short Take #26! As you might already know, the Technology Short Takes are my irregularly-published collections of links, articles, thoughts, and (sometimes) rants. I hope you find something useful here!


  • Chris Colotti, as part of a changed focus in his role at VMware, has been working extensively with Nicira NVP. He’s had a couple of good posts; this one is a primer on how NVP works, and this one discusses the use of the Open vSwitch (OVS) vApp. As I mentioned before in other posts, OVS is popping up in more and more places—it might be a good idea to make sure you’re familiar with it.
  • This article by Ivan Pepelnjak on VXLAN termination on physical devices is over a year old, but still very applicable—especially considering Arista Networks recently announced their 7150S switch, which sports hardware VTEP (VXLAN Tunnel End Point) support (meaning that it can terminate VXLAN segments).
  • Brad Hedlund dives into Midokura Midonet in this post on L2-L4 network virtualization. It’s a good overview (thanks Brad!) and worth reading if you want to get up to speed on what Midokura is doing. (Oh, just as an aside: note that Midokura leverages OVS in their solution. Just saying…)
  • This blog post provides more useful information from Kamau Wanguhu on VXLAN and proxy ARP. Kamau also has an interesting post on network virtualization, although—to be honest—the post is long on messaging/positioning and short on technical information. I prefer the latter instead of the former.


  • This mention of the Dell PowerEdge M I/O Aggregator looks interesting, although I’m still not real clear on exactly what it is or how it works. I guess this first article was a tease?


Nothing this time around, but I’ll stay alert for items to include in future posts!

Cloud Computing/Cloud Management

  • Want to know a bit more about how to configure VXLAN inside VCD? Rawlinson Rivera has a nice write-up that is worth reviewing.
  • Clint Kitson, an EMC vSpecialist, talks about some VCD integrity scripts he created. Looks like some pretty cool stuff—great work, Clint!
  • For the past couple of weeks I’ve been (slowly) reading Kevin Jackson’s OpenStack Cloud Computing Cookbook; it’s very useful. It’s worth a read if you want to get up to speed on OpenStack; naturally, you can get it from Amazon.

Operating Systems/Applications

  • At the intersection of cloud-based storage and configuration management, I happened to find this very interesting Puppet module designed to fetch and update files from an S3 bucket. Through this module, you could store files in S3 instead of using Puppet’s built-in file server. (By the way, this module also works with OpenStack Swift as well.)
  • One of the things I’ve complained about regarding newer versions of OS X is the “hiding” of the Unix underpinnings. Perhaps I should read this book and see if my thinking is unfounded?


  • Chris Evans takes a look at Hyper-V 3.0′s Virtual Fibre Channel feature in this write-up. From what I’ve read, it sounds like Hyper-V’s NPIV implementation is more robust than VMware’s broken and busted NPIV implementation. (If you don’t know why I say that about VMware’s implementation, ask anyone who’s tried to use it.) The real question is this: is NPIV support in a hypervisor of any value any longer?
  • Gina Minks (formerly of Dell, now with Inktank) recommended I have a look at Ceph and mentioned this post on migrating to Ceph (with a little libvirt thrown in).
  • Gluster might be another project that I need to spend some time examining; this post on using Gluster with oVirt 3.1 looks interesting. Anyone have any pointers for a Gluster beginner?
  • Mirantis has a post about some Nova Volume integration with Isilon. I’ve often said that I think scale-out platforms like Isilon (among others) are an important foundation for future storage solutions. It’s cool to see some third-party development happening to integrate Isilon and OpenStack.


That’s all for this time around. As always, courteous comments are welcome (encouraged, in fact!), so feel free to speak up in the comments below. I’d love to hear your feedback.

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Welcome to Technology Short Take #24, another instance of my irregularly-published collection of links, thoughts, and rants on various data center technologies like networking, operating systems, security, hardware, virtualization, and cloud computing. This is a slightly shorter version of my Technology Short Takes; I’m trying to pare down since some readers have indicated the previous Short Takes weren’t short enough. Anyway, I hope you find something useful.


  • This page is a decent reference to the open source software-defined networking (SDN) projects that are out there. While I’m sure it’s not comprehensive—open source projects can be difficult to track sometimes—it’s at least a good starting point.
  • Here’s an older article by Brad Hedlund on building a leaf-spine design with either 40G or 10G. Which is better? As usual, the IT answer is, “It depends.” It’s a good article overall, although it reminds me that I still have so much to learn in networking. It’s a good thing there are smart folks like Brad who are willing to share their knowledge.


  • Bromium finally “opened the kimono” to talk about what they’re doing. I had the chance to chat with Simon Crosby, and I must say that it’s pretty cool stuff. If you haven’t yet read it, check out Simon’s post at BrianMadden.com.
  • While I was in Indianapolis last week for the Indianapolis VMUG, I sat in on a session by Lancope on the use of Netflow to secure your network. The presenter showed a list of open source Netflow tools. I haven’t gotten the specific list that the presenter used, but I did find this list—perhaps it will be useful.


  • In 2009 I wrote a piece explaining NPIV and NPV. In May Tony Bourke posted a write-up of NPIV and NPV as well, and did a good job of drawing some analogies about these technologies. There’s a great discussion going on in the comments as well, so I recommend reading the comments too.
  • This article is titled “Understanding IO,” but it really seems like more of a write-up on various IO analysis tools. Still quite useful, even though it seems to be a bit focused on Solaris.
  • I finally got around to reading Stephen Foskett’s I/O Blender series (part 1, part 2, and part 3), in which he describes the current state of storage and virtualization as a introduction to some of the ideas that VMware described in their “next-generation” storage presented last year at VMworld 2011; in particular, the demultiplexer.


  • Maish Saidel-Keesing has a three-part write-up on installing and configuring OpenIndiana in a VM (part 1, part 2, and part 3). This is not something I’ve had the opportunity to work with, although I have worked some with Solaris in the past. (In fact, this weekend I tried to find a Solaris 10 x86 ISO I used to have somewhere because I was going to build a Solaris 10 VM for some Puppet testing and couldn’t find it. Bummer.)
  • Via Vladan Seget, I saw that VMware vSphere 5.0 has achieved Common Criteria EAL4+ certification.
  • This VMware KB article has a great PDF attached that covers vSphere’s various memory management techniques.
  • Working your way toward taking the VCAP-DCD exam? This site, while a bit dated, has some good resources for VDCD410 (the vSphere 4 version of the exam). Of course, there’s also this little video training course that was recently released…
  • Here’s a Citrix Knowledge Center article that provides more information on SR-IOV (Single Root I/O Virtualization) support within XenServer (and, by extension, Xen Cloud Platform/XCP).
  • There’s an interesting note here about interactions between SIOC and SRM 5.

That’s it for this time around; feel free to add your own thoughts in the comments below. Courteous comments are always welcome!

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Yesterday on Twitter I asked this question:

If you had to pick the top 5 open source tools/projects to learn in order to stay sharp/relevant, what would they be?

A number of people expressed interest in the answers to that question, so I thought I post it here. My reason for asking isn’t just academic; I plan to use this feedback (as well as any feedback in the comments to this blog post) to further tweak my 2012 projects (see here and here).

Here are the answers I received back, followed by the number of people who suggested that particular tool or project:

Puppet (5 responses)
Python (3 responses)
Linux, general skills (1 response)
CloudStack (1 response)
OpenStack (4 responses)
Node.js (1 response)
Chef (1 response)
Riak (1 response)
Nginx (1 response)
Graphite (1 response)
Reimann (1 response)
KVM (4 responses)
Zabbix (1 response)
MongoDB/Cassandra (2 responses)
Hadoop (4 responses)
Metasploit (1 response)
Apache (1 response)

These responses are, by and large, consistent with the feedback that I received on my original 2012 projects post. Thus far I have resisted switching my focus from Xen to KVM, but it seems increasingly more evident that it would be most efficient to look at KVM and OpenStack together. (Those of you who suggested that at the beginning of the year, feel free to now say “I told you so.” It won’t offend me.) I can further combine that with Puppet to explore the use of Puppet in configuring OpenStack nodes and/or configuring VM instances running on OpenStack.

I’d love to continue to get more feedback, so please take the time to share your thoughts on the “top 5″ open source tools/projects you’d recommend for a virtualization/data center guy (like me) to stay relevant and sharp in this fast-moving industry. Courteous comments are always welcome!

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As part of my 2012 projects (see here plus an update here), I’ve been familiarizing myself with the Xen hypervisor. To that end, I’ve been working to get XCP (Xen Cloud Platform, the open source version of XenServer) running on a test system in my home office. It’s been a bit of a struggle, but I think I’ve finally got it, and I wanted to share the information here.

Here are the steps that I followed to install XCP-XAPI on a system running Ubuntu Server 12.04 LTS. Much of the credit goes to Project Kronos and this page in particular on the XCP toolstack on a Debian-based installation. While the XCP toolstack page is quite helpful, I found that the instructions were confusing (for me, at least). Hence, I’m writing up my steps in the hopes that they will prove useful to someone else.

Before Installing XCP-XAPI

Before I started the installation of the XCP-XAPI packages, I first made sure that all the various networking interfaces were configured correctly and working as expected. For my particular system (a Dell Latitude E6400), this meant installing some proprietary Broadcom wireless firmware (using the firmware-b43-lpphy-installer package) and configuring /etc/network/interfaces. I also ran apt-get update and apt-get upgrade to install the latest versions of all packages. Credit goes to this page for instructions on how to configure the wireless NIC from the CLI, with one small correction. In the /etc/network/interfaces file, I had to use this as the pre-up parameter (the example on the page above used “-Bw” instead of “-B”):

pre-up wpa_supplicant -B -Dwext -iwlan0

(Naturally you’d write that all as one line; it’s broken here for readability.)

Installing XCP-XAPI

First, I edited /etc/apt/sources.list to add repositories for the XCP-XAPI packages. Although Ubuntu 12.04 LTS provides XCP-XAPI packages, the Project Kronos page indicated that there were dependency issues, so I went with these packages instead. If anyone has any experience with the Ubuntu-provided XCP-XAPI packages, please let me know.

I added these lines:

deb http://ppa.launchpad.net/ubuntu-xen-org/xcp-unstable/ubuntu precise main
deb-src http://ppa.launchpad.net/ubuntu-xen-org/xcp-unstable/ubuntu precise main

Then I ran this command:

apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 9273A937

That was followed by:

apt-get update
apt-get install xcp-xapi

From there, apt-get started fetching and installing the necessary packages (and there are quite a few). When prompted, I selected to use OpenvSwitch as the networking backend (instead of standard Linux bridging).

Before rebooting—which you’ll need to do in order to boot into the Xen kernel—I also performed the following steps.

  1. I edited the /etc/init.d/xend file to prevent xend from starting up. (Note that I deliberately split the two sed commands here for easier readability.)
  2. sed -i -e 's/xend_start$/#xend_start/' /etc/init.d/xend
    sed -i -e 's/xend_stop$/#xend_stop/' /etc/init.d/xend
    update-rc.d xendomains disable
  3. I set the XAPI toolstack as the default by editing /etc/default/xen and changing the line TOOLSTACK="" to TOOLSTACK="xapi".

  4. I made the Xen kernel the default grub entry by editing /etc/default/grub and setting GRUB_DEFAULT="Xen 4.1-amd64". Then I ran update-grub.

  5. I added a symbolic link from /usr/share/qemu-linaro/keymaps to /usr/share/qemu/keymaps.

At this point, the system is ready for a reboot.

Verifying that XCP-XAPI Works

I’m still working on a more comprehensive set of tests, but some basic tests should tell you whether the system is working or not:

  1. Run xe host-list. It should return a single host, which is the system you just built.
  2. Run xe vm-list. The information returned should list a single VM described as the control domain on the host.
  3. Run xe network-list. You should get back a network for each network interface, plus another network for XenAPI communications.
  4. Run xe sr-list. You should get back a single SR (storage repository) used for XenServer Tools ISOs.

(By the way, note that xe requires a username and password, even if you’re running it against the local host. I found it easiest to create a password file and then create an alias for xe that included the -pwf parameter.)

I have future posts planned that will talk more about networking and SRs with this Ubuntu-based XCP-XAPI system, so stay tuned for those. Also, if you have any tips or tricks for making this process easier (or if I’ve stated something incorrectly), please speak up in the comments. Thanks!

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In early January, I posted a 2012 project list. To summarize, here are the four broad goals that I set for myself for 2012:

  1. Learn to script in Perl.
  2. Learn to speak German.
  3. Become very familiar with the Xen hypervisor.
  4. Pursue CCNP certification.

Now that we are halfway through the year, where do things stand? Here’s a quick update.

  1. My Perl skills are still really elementary. The biggest challenge I’ve found is that without some sort of task or process to try to automate, trying to write code in Perl is kind of “disconnected.” Yes, you can walk through the sample code and the exercises in the book, but to make it real you need a relevant challenge. I’ve been searching for some common tasks to try to automate, but haven’t had a great deal of success yet.

  2. My German is progressing, but ever so slowly. I’m right now about one-third of the way through the Rosetta Stone modules I have.

  3. Learning Xen is also progressing. I do have a Xen Cloud Platform (XCP) system up and running in my home office; I’ve been installing and re-installing it so as to get a better feel for the intricacies involved. It’s currently broken—time for another rebuild!

  4. I have created the study framework for key topics on the CCNP ROUTE exam and am now adding content to the study framework. I haven’t yet taken any exams, so I guess you could say I haven’t really made any measurable progress on this goal.

All in all, I haven’t made the progress that I would have liked to make, given the timeframe. Not to make excuses, but there are two factors that have affected me more significantly than I had anticipated: travel and my video training project with Train Signal. Of the limited progress that I have made, most of it was in Q1, before I started my Train Signal project. Since I started the video training series, my travel has also picked up, and I’ve found that it’s extremely difficult to work on the video series while I’m traveling. Thus, the video training series has taken a lot more of my time than I had originally expected, and has stalled progress on my other initiatives.

So is a “mid-course correction” necessary? I think that it is. Here are the changes I’m making:

  1. Learning Perl: At this point, I’m putting my Perl efforts on hold. For me, the biggest obstacle in learning to script in Perl was having relevant tasks that need to be scripted, and that’s where I came up short. I simply couldn’t find tasks that I wanted or needed to automate in Perl. A number of readers commented on my original article that my choice of projects wasn’t particularly synergistic, and perhaps that is what is being reflected here.

  2. Learning German: To help encourage me to work on my German more frequently, I’m going to change the OmniFocus actions so that I need to complete modules on a more regular basis. (As I’ve written before elsewhere, I use OmniFocus to help keep me on track with projects and responsibilities.)

  3. Learning Xen: I’m continuing with Xen. Progress has been slow, but there has been progress. Several readers suggested I focus on KVM instead, but for now I’m going to stick it out with Xen. The primary challenge here has been finding good sources of information. Don’t be too surprised to see some blog posts as I wrestle through certain areas; perhaps these posts can be helpful to others.

  4. Pursue CCNP: My pursuit of CCNP will continue. I already have study framework documents created, and I hope to turn up a router simulation environment (using GNS3 or similar) soon. From the beginning I never intended to actually attain CCNP by year end (that’s 3 exams), but simply to make measurable progress (1 exam passed).

That’s where things stand, halfway through 2012. Perhaps these goals are ambitious, but I do believe that it’s necessary to challenge ourselves, to never remain static and dormant—otherwise we risk becoming irrelevant in a fast-paced world of changing technologies.

I welcome any suggestions, thoughts, or criticisms (courteous and constructive, of course!) in the comments below.

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Welcome to Technology Short Take #23, another collection of links and thoughts related to data center technologies like networking, storage, security, cloud computing, and virtualization. As usual, we have a fairly wide-ranging collection of items this time around. Enjoy!


  • A couple of days ago I learned that there are a couple open source implementations of LISP (Locator/ID Separation Protocol). There’s OpenLISP, which runs on FreeBSD, and there’s also a project called LISPmob that brings LISP to Linux. From what I can tell, LISPmob appears to be a bit more focused on the endpoint than OpenLISP.
  • In an earlier post on STT, I mentioned that STT’s re-use of the TCP header structure could cause problems with intermediate devices. It looks like someone has figured out how to allow STT through a Cisco ASA firewall; the configuration is here.
  • Jose Barreto posted a nice breakdown of SMB Multichannel, a bandwidth-enhancing feature of SMB 3.0 that will be included in Windows Server 2012. It is, unexpectedly, only supported between two SMB 3.0-capable endpoints (which, at this time, means two Windows Server 2012 hosts). Hopefully additional vendors will adopt SMB 3.0 as a network storage protocol. Just don’t call it CIFS!
  • Reading this article, you might deduce that Ivan really likes overlay/tunneling protocols. I am, of course, far from a networking expert, but I do have to ask: at what point does it become necessary (if ever) to move some of the intelligence “deeper” into the stack? Networking experts everywhere advocate the “complex edge-simple core” design, but does it ever make sense to move certain parts of the edge’s complexity into the core? Do we hamper innovation by insisting that the core always remain simple? As I said, I’m not an expert, so perhaps these are stupid questions.
  • Massimo Re Ferre posted a good article on a typical VXLAN use case. Read this if you’re looking for a more concrete example of how VXLAN could be used in a typical enterprise data center.
  • Bruce Davie of Nicira helps explain the difference between VPNs and network virtualization; this is a nice companion article to his colleague’s post (which Bruce helped to author) on the difference between network virtualization and software-defined networking (SDN).
  • The folks at Nicira also collaborated on this post regarding software overhead of tunneling. The results clearly favor STT (which was designed to take advantage of NIC offloading) over GRE, but the authors do admit that as “GRE awareness” is added to the cards that protocol’s performance will improve.
  • Oh, and while we’re on the topic of SDN…you might have noticed that VMware has taken to using the term “software-defined” to describe many of the services that vSphere (and related products) provide. This includes the use of software-defined networking (SDN) to describe the functionality of vSwitches, distributed vSwitches, vShield, and other features. Personally, I think that the term software-based networking (SBN) is far more applicable than SDN to what VMware does. It is just me?
  • Brad Hedlund wrote this post a few months ago, but I’m just now getting around to commenting about it. The gist of the article—forgive me if I munge it too much, Brad—is that the use of open source software components might dramatically change the shape/way/means in which networking protocols and standards are created and utilized. If two components are communicating over the network via open source components, is some sort of networking standard needed to avoid being “proprietary”? It’s an interesting thought, and goes to show the power of open source on the IT industry. Great post, Brad.
  • One more mention of OpenFlow/SDN: it’s great technology (and I’m excited about the possibilities that it creates), but it’s not a silver bullet for scalability.


  • I came across this interesting post on a security attack based on VMDKs. It’s quite an interesting read, even if the probability of being able to actually leverage this attack vector is fairly low (as I understand it).


  • Chris Wahl has a good series on NFS with VMware vSphere. You can catch the start of the series here. One comment on the testing he performs in the “Same Subnet” article: if I’m not mistaken, I believe the VMkernel selection is based upon which VMkernel interface is listed in the first routing table entry for the subnet. This is something about which I wrote back in 2008, but I’m glad to see Chris bringing it to light again.
  • George Crump published this article on using DCB to enhance iSCSI. (Note: The article is quite favorable to Dell, and George discloses an affiliation with Dell at the end of the article.) One thing I did want to point out is that—if I recall correctly—the 802.1Qbb standard for Priority Flow Control only defines a single “no drop” class of service (CoS). Normally that CoS is assigned to FCoE traffic, but in an environment without FCoE you could assign it to iSCSI. In an environment with both, that could be a potential problem, as I see it. Feel free to correct me in the comments if my understanding is incorrect.
  • Microsoft is introducing data deduplication in Windows Server 2012, and here is a good post providing an introduction to Microsoft’s deduplication implementation.
  • SANRAD VXL looks interesting—anyone have any experience with it? Or more detailed technical information?
  • I really enjoyed Scott Drummonds’ recent storage performance analysis post. He goes pretty deep into some storage concepts and provides real-world, relevant information and recommendations. Good stuff.

Cloud Computing/Cloud Management

  • After moving CloudStack to the Apache Software Foundation, Citrix published this discourse on “open washing” and provides a set of questions to determine the “openness” of software projects with which you may become involved. While the article is clearly structured to favor Citrix and CloudStack, the underlying point—to understand exactly what “open source” means to your vendors—is valid and worth consideration.
  • Per the AWS blog, you can now export EC2 instances out of Amazon and into another environment, including VMware, Hyper-V, and Xen environments. I guess this kind of puts a dent in the whole “Hotel California” marketing play that some vendors have been using to describe Amazon.
  • Unless you’ve been hiding under a rock for the past few weeks, you’ve most likely heard about Nick Weaver’s Razor project. (If you haven’t heard about it, here’s Nick’s blog post on it.) To help with the adoption/use of Razor, Nick also recently announced an overview of the Razor API.


  • Frank Denneman continues to do a great job writing solid technical articles. The latest article to catch my eye (and I’m sure that I missed some) was this post on combining affinity rule types.
  • This is an interesting post on a vSphere 5 networking bug affecting iSCSI that was fixed in vSphere 5.0 Update 1.
  • Make a note of this VMware KB article regarding UDP traffic on Linux guests using VMXNET3; the workaround today is using E1000 instead.
  • This post is actually over a year old, but I just came across it: Luc Dekens posted a PowerCLI script that allows a user to find the maximum IOPS values over the last 5 minutes for a number of VMs. That’s handy. (BTW, I have fixed the error that kept me from seeing the post when it was first published—I’ve now subscribed to Luc’s blog.)
  • Want to use a Debian server to provide NFS for your VMware environment? Here is some information that might prove helpful.
  • Jeremy Waldrop of Varrow provides some information on creating a custom installation ISO for ESXi 5, Nexus 1000V, and PowerPath/VE. Cool!
  • Cormac Hogan continues to pump out some very useful storage-focused articles on the official VMware vSphere blog. For example, both the VMFS locking article and the article on extending an EagerZeroedThick disk were great posts. I sincerely hope that Cormac keeps up the great work.
  • Thanks to this Project Kronos page, I’ve been able to successfully set up XCP on Ubuntu Server 12.04 LTS. Here’s hoping it gets easier in future releases.
  • Chris Colotti takes on some vCloud Director “challenges”, mostly surrounding vShield Edge and vCloud Director’s reliance on vShield Edge for specific networking configurations. While I do agree with many of Chris’ points, I personally would disagree that using vSphere HA to protect vShield Edge is an acceptable configuration. I was also unable to find any articles that describe how to use vSphere FT to protect the deployed vShield appliances. Can anyone point out one or more of those articles? (Put them in the comments.)
  • Want to use Puppet to automate the deployment of vCenter Server? See here.

I guess it’s time to wrap up now, lest my “short take” get even longer than it already is! Thanks for reading this far, and I hope that I’ve shared something useful with you. Feel free to speak up in the comments if you have questions, thoughts, or clarifications.

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Rather than posting some sort of “2011 in review” article where I talk about how many visitors the site had or how many RSS subscribers there are, I thought I’d instead focus on the upcoming year and some of the projects in which I’ll be involved. By describing some of the projects that I’m undertaking this year in 2012, that gives you—the readers—a rough idea of some of the types of content that will likely appear in the coming year.

Here are some of my 2012 projects (some of these I’ve already tweeted about):

  1. I’m going to learn to script in Perl. Many people have asked why Perl and why not Python or Ruby or something else. Honestly, I don’t have a really good answer for you. I tried (unsuccessfully) to teach myself Perl a couple of years ago, so I still have the O’Reilly Learning Perl book. Rather than spending money to learn some other scripting language, it seemed reasonable to revisit Perl again and just leverage the resources I already have. You might see a few Perl-related posts here and there as I work through Learning Perl, but I’ll try not to bore you with elementary stuff.

  2. I’m going to learn German. Same scenario here—many people have asked why German and why not Spanish or French. I do have an answer this time: I seem to be spending a fair amount of time in Vienna, so German seemed to make sense. I also have a series of customer meetings planned in Germany in the first quarter of this year. Plus, German is completely new and different than anything I’ve learned before, and I wanted to challenge myself to learn and think in new ways. It’s unlikely that this will find its way into any blog posts, but you never know…

  3. I’m going to become much more familiar with the Xen hypervisor. I haven’t yet decided if I’ll focus strictly on the open source version of Xen or Citrix XenServer; I’m open to suggestions there. No, this doesn’t mean that I’m abandoning VMware or anything like that; I just want to expand my knowledge. You can’t simply discount Xen; after all, Amazon EC2 is built on Xen. Along with this dive into Xen, I’ll also be looking very closely at Open vSwitch and OpenStack. I’d expect that a great deal of this education will eventually end up in various blog posts here.

  4. I’m going to pursue my CCNP. I “re-achieved” CCNA last year, and this year I’m pursuing my CCNP. As with Xen, I’m confident that the learning curve required to move closer to (or even achieve) CCNP will result in a number of related blog posts on various networking technologies or concepts.

I do have a few other projects planned for this upcoming year, but I’m not quite ready to discuss those publicly yet. At least one of these other projects will be something new that I haven’t done before. Stretching myself and my skills/experience in new directions is a bit of a theme this year.

If you have any tips/tricks/advice to share on any of these upcoming projects, or if there are specific things related to these projects that you’d like to see blogged about here, please let me know in the comments. Thanks, and I hope that 2012 is going to be as exciting for you as it will be for me!

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