Posts Tagged ‘VMware’

I’m a VCAP4-DCD and VCDX4

January 11th, 2011

Bless me readers for I have sinned.  It has been nearly five weeks since my last blog entry.  Since then I’ve acquired numerous electronic distractions in the house and took a little vacation from work and virtualization.  I also randomly and unprovoked received a Microsoft Hyper-V sticker in the mail from Stephen Foskett and I have been thinking about revenge almost daily.  (no, not really)

Yes it has been a while and I did take a break from work and all things virtual for some family time and “me time” over the holidays.  So let me get the needfully ubiquitous out of the way by saying Happy New Year to all!  I hope 2011 brings continued health to your family, joy into your life, success into your career, agility into your VMware virtualized datacenter/private cloud, and uncontested Secure Multi-Tenancy into your public cloud.

For me personally, success starts early in 2011.  As you probably guessed by the title, I got some great news from VMware tonight in that.. well you can read it verbatim:

Congratulations on passing the VMware Certified Advanced Professional on vSphere4 – Datacenter Design exam!

I’m now a VCAP4-DCD.  I a few weeks later I was notified by VMware that I was assigned VCAP4-DCD #35.

Passing this exam is great on a few levels.  I now have the VCAP4-DCD certification to go along with the VCAP4-DCA credentials I picked up a few months ago.  In addition to that, the VCAP4-DCD pass also upgrades my VCDX3 certification to VCDX4.  I haven’t received the official word on that from VMware yet but I’ve met the requirements and notification which I expect within the next few months is more or less a formality.  I’m pretty happy to have these achievements, and particularly early on.  With no other certifications currently in sight, I can conitnue forward working on various projects and initiatives.  If you thought I ran out of things to write about, that’s not the case.  I’ve got plenty in the queue.  One benefit I value working with products in an enterprise environment as opposed to strictly working on the education/instructor side of the fence is that there is no shortage of experience gained and lessons learned while working in the trenches.  I work in a blend of VMware vSphere design and operations which I think is an exceptional example of Yin and Yang because they perpetually stregthen each other through experience.

By the way.. on the electronic distractions.. my family (this was a collaborative decision) picked up our first gaming console.  We got the PS3.  My PlayStation Network ID is VCDX034.  Hit me up if you’re interested in a game of NHL 11 or Madden 11.  I’m not very good but I’ll take a beating and I’m a good sport about it.  VCAP4-DCD achievement unlocked. VCDX4 achievement unlocked.  See what I did there? 😎

Update 8/18/11:  No VCDX4 certificate or welcome kit received yet.

IBM x3850 M2 shows 8 sockets on ESXi 4.1

December 9th, 2010

Working with an IBM x3850 M2, I noticed VMware ESXi 4.1 was reporting 8 processor sockets when I know this model has only 4 sockets.  It was easily noticable as I ran out of ESX host licensing prematurely.  The problem is also reported with the IBM x3950 M2 in this thread.

SnagIt Capture

SnagIt Capture

Here’s the fix:  Reboot the host and flip a setting in the BIOS.

POST -> F1 -> Advanced Setup -> CPU Options -> Clustering Technology. Toggle the Clustering Technology configuration from Logical Mode to Physical Mode.

After the above change is made, sanity is restored in that ESXi 4.1 will properly see 4 sockets and licenses will be consumed appropriately.

SnagIt Capture

SnagIt Capture

Memory Compression Video

December 9th, 2010

Vladan SEGET created a blog post on VMware ESX(i) 4.1 Memory Compression.  In his post, he linked to a fantastically simple vmwaretv video demonstration  of memory compression in action compared to a hypervisor with no memory compression enabled.  For anyone looking for the tool used in the video to perform your own memory compression testing but cannot find it, it’s “around”.  Let me know and I might be able to help you find it.

I was going to update my memory compression blog post crediting Vladan and embedding the video, but sadly, I have no memory compression blog post yet!  So instead, I send you to Vladan’s ESX Virtualization blog using the link above.

Note to self: create a memory compression blog post.

VMware vSphere 4.1 HA and DRS technical deepdive arrival

December 7th, 2010

IMG01201-20101207-1659

I think Eric “Scoop” Sloof was the first to announce this yesterday, complete with a video and everything! Come on Eric, let some of the other bloggers have your scraps. 😎

I received a copy of a brand new book hot off the presses titled VMware vSphere 4.1 HA and DRS technical deepdive by Duncan Epping and Frank Denneman.  Having just received it tonight, of course I haven’t had time to finish reading it yet.  This is the pre-game party blog post.  Just by thumbing through the pages, I’m going to draw a few conclusions.  I’ll see if I’m right by the time I actually finish reading the book.

  1. 224 pages and 18 chapters in length.  I’ve seen entire virtual infrastructure books which have been written in as many or less pages than this.  And this book covers just HA and DRS.
    Conclusion: Even factoring in a fair amount of diagrams, this will be the most comprehensive HA and DRS handbook in existence.
  2. HA and DRS are perhaps two of the most misunderstood and misinterpreted technologies in VMware’s suite of virtual infrastructure offerings.  What exactly is confusing about these tools?  First, they are both set-it-and-forget-it automation.  The technologies will more or less “just work” out of the box.  This simplicity bestows an overwhelming amount of confidence in cluster configuration because the complexity is masked by an easy to use interface.
    Conclusion: There’s a lot going on under the hood in both HA and DRS that administrators should know about to properly configure and tune their environment.  The detail this book goes into should rock your world.
  3. This book covers DPM.
    Conclusion: That is good.
  4. There are many great looking diagrams and flowcharts.
    Conclusion: Very helpful in reinforcing what’s written in detail.

I look forward to relaxing with this book while on vacation the rest of this week.  Nice job from what I’ve seen so far guys!

You can read a review, write a review, or purchase this book on Amazon’s web site here.

Flow Control

November 29th, 2010

Thanks to the help from blog sponsorship, I’m able to maintain a higher performing lab environment than I ever had been up until this point.  One area which I hadn’t invested much in, at least from a lab standpoint, is networking.  In the past, I’ve always had some sort of small to mid density unmanageable Ethernet switch.  And this was fine.  Household name brand switches like Netgear and SMC from Best Buy and NewEgg performed well enough and survived for years in the higher temperature lab environment.  Add to that, by virtue of being unmanaged, they were plug and play.  No time wasted fighting a mis configured network. 

I recently picked up a 3Com SuperStack 3 Switch 3870 (48 1GbE ports).  It’s not 10GbE but it does fit my budget along with a few other networking nice-to-haves like VLANs and Layer 3 routing.  Because this switch is managed, I can now apply some best practices from the IP based storage realm.  One of those best practices is configuring Flow Control for VMware vSphere with network storage.  This blog post is mainly to record some pieces of information I’ve picked up along the way and to open a dialog with network minded readers who may have some input.

So what is network Flow Control? 

NetApp defines Flow Control in TR-3749 as “the process of managing the rate of data transmission between two nodes to prevent a fast sender from over running a slow receiver.”  NetApp goes on to advise that Flow Control can be set at the two endpoints (ESX(i) host level and the storage array level) and at the Ethernet switch(es) in between.

Wikipedia is in agreement with the above and adds more meat to the discussion including the following “The overwhelmed network element will send a PAUSE frame, which halts the transmission of the sender for a specified period of time. PAUSE is a flow control mechanism on full duplex Ethernet link segments defined by IEEE 802.3x and uses MAC Control frames to carry the PAUSE commands. The MAC Control opcode for PAUSE is 0X0001 (hexadecimal). Only stations configured for full-duplex operation may send PAUSE frames.

What are network Flow Control best practices as they apply to VMware virtual infrastructure with NFS or iSCSI network storage?

Both NetApp and EMC agree that Flow Control should be enabled in a specific way at the endpoints as well as at the Ethernet switches which support the flow of traffic:

  • Endpoints (that’s the ESX(i) hosts and the storage arrays) should be configured with Flow Control send/tx on, and receive/rx off.
  • Supporting Ethernet switches should be configured with Flow Control “Desired” or send/tx off and receive/rx on.

One item to point out here is that although both mainstream storage vendors recommend these settings for VMware infrastructures as a best practice, neither of their multi protocol arrays ship configured this way.  At least not the units I’ve had my hands on which includes the EMC Celerra NS-120 and the NetApp FAS3050c.  The Celerra is configured out of the box with Flow Control fully disabled and I found the NetApp configured for Flow Control set to full (duplex?).

Here’s another item of interest.  VMware vSphere hosts are configured out of the box to auto negotiate Flow Control settings.  What does this mean?  Network interfaces are able to advertise certain features and protocols which they were purpose built to understand following the OSI model and RFCs of course.  One of these features is Flow Control.  VMware ESX ships with a Flow Control setting which adapts to its environment.  If you plug an ESX host into an unmanaged switch which doesn’t advertise Flow Control capabilities, ESX sets its tx and rx flags to off.  These flags tie specifically to PAUSE frames mentioned above.  When I plugged in my ESX host into the new 3Com managed switch and configured the ports for Flow Control to be enabled, I subsequently found out using the ethtool -a vmnic0 command that both tx and rx were enabled on the host (the 3Com switch has just one Flow Control toggle: enabled or disabled).  NetApp provides a hint to this behavior in their best practice statement which says “Once these [Flow Control] settings have been configured on the storage controller and network switch ports, it will result in the desired configuration without modifying the flow control settings in ESX/ESXi.”  Jase McCarty pointed out back in January a “feature” of the ethtool in ESX.  Basically, ethtool can be used to display current Ethernet adapter settings (including Flow Control as mentioned above) and it can also be used to configure settings.  Unfortunately, when ethtool is used to hard code a vmnic for a specific Flow Control configuration, that config lasts until the next time ESX is rebooted.  After reboot, the modified configuration does not persist and it reverts back to auto/auto/auto.  I tested with ESX 4.1 and the latest patches and the same holds true.  Jase offers a workaround in his blog post which allows the change to persist by embedding it in /etc/rc.local.

Third item of interest.  VMware KB 1013413 talks about disabling Flow Control using esxcfg-module for Intel NICs and ethtool for Broadcom NICs.  This article specifically talks about disabling Flow Control when PAUSE frames are identified on the network.  If PAUSE frames are indicative of a large amount of traffic which a receiver isn’t able to handle, it would seem to me we’d want to leave Flow Control enabled (by design to mediate the congestion) and perform root cause analysis on exactly why we’ve hit a sustained scaling limit (and what do we do about it long term).

Fourth.  Flow Control seems to be a simple mechanism which hinges on PAUSE frames to work properly.  If the Wikipedia article is correct in that only stations configured for full-duplex operation may send PAUSE frames, then it would seem to me that both network endpoints (in this case ESX(i) and the IP based storage array) should be configured with Flow Control set to full duplex, meaning both tx and rx ON.  This conflicts with the best practice messages from EMC and NetApp although it does align with the FAS3050 out of box configuration.  The only reasonable explanation is that I’m misinterpreting the meaning of full-duplex here.

Lastly, I’ve got myself all worked up into a frenzy over the proper configuration of Flow Control because I want to be sure I’m doing the right thing from both a lab and infrastructure design standpoint, but in the end Flow Control is like the Shares mechanism in VMware ESX(i):  The values or configurations invoked apply only during periods of contention.  In the case of Flow Control, this means that although it may be enabled, it serves no useful purpose until a receiver on the network says “I can’t take it any more” and sends the PAUSE frames to temporarily suspend traffic.  I may never reach this tipping point in the lab but I know I’ll sleep better at night knowing the lab is configured according to VMware storage vendor best practices.

More VCDX Insight and a New Blog

November 17th, 2010

Yuri Semenikhin, a Systems Engineer from Georgia, Tbilisi, has recently launched a virtualization blog by the name of vEra of the Virtual Revolution.  Yuri published his VCDX certification attempt experience in his blog post VCDX “be or not to be”. not YET !  His writing is not in English, however, he offers an English translator on the right hand edge of his blog. 

While some compare the VCDX to the Cisco CCIE certification, Yuri contrasts the two by saying the CCIE is a technical certification mapping closer to the VCAP4-DCA while the VCDX is an architect certification.  I would agree the VCAP-DCA exam compares to the CCIE from a hands on lab approach and the VCAP-DCA was plenty difficult, but I don’t think the VCAP-DCA requires near the level of training, preparation, and expense (or investment, depending on your view) that the CCIE lab exam does.  This is merely a difference in opinion and I’m not saying either is right or wrong.

The purpose of my blog post is to provide some exposure to Yuri and his blog.  Yuri tells his story in great length and detail.  I wish him the best of luck with his blog and his next VCDX attempt!

Submit a VMware Feature Request

November 13th, 2010

SnagIt Capture

If you have a suggestion for how to improve or enhance VMware software, VMware always welcomes your input. Please submit your suggestions through the Feature Request form on VMware’s website. Unless additional information is needed, you will not receive a personal response. Any suggestions for enhancements to VMware software that you submit will become the property of VMware. VMware may use this information for any VMware business purposes, without restriction, including for product support and development. VMware will not use the information in a form that personally identifies you.

http://www.vmware.com/support/policies/feature.html

Provide your input to VMware and help them maintain status as the most innovative, flexible, and scalable hypervisor on the planet.