Yellow Bricks

by Duncan Epping

VMware

New Beta Program option: VMware Hosted Beta

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Many of you probably have participated in one of the many beta programs VMware has offered in the last couple of years. I personally have participated in various beta programs when I was a customer / partner and I always loved going through the various exercises. The challenging part for me always was finding the time to setup the environment.

Recently VMware started offering a new way to participate in the evaluation and feedback of VMware’s developing products. The VMware Beta Program is now offering a Hosted Beta; providing registered users access to pre-build online Lab environments with guided workflows to get a closer look at the latest and greatest VMware technologies without the need to build-out infrastructure onsite.

This hosted technology is based on the same technologies used for the Hands-On Labs (HOL) at VMworld, providing a fully built environment to explore intricate product features while requiring nothing more than an HTML5 compliant browser and the latest View Client.

In my opinion this is a great opportunity to test-drive products and provide VMware with your feedback on the features still under development. On top of that this will allow you to spend 1-2 hour blocks to get acquainted with new technology, without the need to be on-site. You can do this at the office, or at home with just a connection to the internet.

If you are interested and want to learn more about the VMware Beta Program you can go here: http://communities.vmware.com/community/vmtn/beta

If you are interested in joining the VMware Beta Program you can either work with your VMware account team or submit a participation request form found here: http://communities.vmware.com/community/beta/betainterest

Awesome Fling: vCenter 5.1 Pre-Install Check

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One of the things that many people have asked me is how they could check if their environment was meeting the requirements for an upgrade to 5.1. Until today I never really had a good answer for it but fortunately that has changed. Alan Renouf has spent countless of hours developing a script that validated your environment and assesses if it is ready for an upgrade to vSphere 5.1.

This is a PowerShell script written to help customers validate their environment and assess if it is ready for a 5.1.x upgrade. The script checks against known misconfiguration and issues raised with VMware Support. This script checks the Windows Server and Active Directory configuration and provides an on screen report of known issues or configuration issues, the script also provides a text report which can help with further trouble shooting.

Is that helpful or what? Instead of going through the motion your just run this pre-flight script and it will tell you if you are good to go or not, or if changes are required. If you are planning an upgrade or are about to upgrade make sure to run this script.

Awesome job Alan, lets keep these coming!

Why the world needs Software Defined Storage

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Yesterday I was at a Software Defined Datacenter event organized by IBM and VMware. The famous Cormac Hogan presented on Software Defined Storage and I very much enjoyed hearing about the VMware vision and of course Cormac’s take on this. Coincidentally, last week I read this article by long-time community guru Jason Boche on VAAI and number of VMs, and after a discussion with a customer yesterday (at the event) about their operational procedures for provisioning new workloads I figured it was time to write down my thoughts.

I have seen many different definitions so far for Software Defined Storage and I guess there is a source of truth in all of them. Before I explain what it means to me, let me describe commonly faced challenges people have today.

In a lot of environments managing storage and associated workloads is a tedious task. It is not uncommon to see large spreadsheets with a long list of LUNs, IDs, Capabilities, Groupings and whatever more is relevant to them and their workloads. These spreadsheets are typically used to decide where to place a virtual machine or virtual disk. Based on the requirements of the application a specific destination will be selected. On top of that, a selection will need to be made based on currently available disk space of a datastore and of course the current IO load. You do not want to randomly place your virtual machine and find out two days later that you are running out of disk space… Well, that is if you have a relatively mature provisioning process. Of course it is also not uncommon to just pick a random datastore and hope for the best.

To be honest, I can understand many people randomly provision virtual machines. Keeping track of virtual disks, datastores, performance, disk space and other characteristics… it is simply too much and boring. Didn’t we invent computer systems to do these repeatable boring tasks for us? That leads us to the question where and how Software Defined Storage should help you?

A common theme recurring in many “Software Defined” solutions presented by VMware is:

Abstract, Pool, Automate.

This also applies to Software Defined Storage in my opinion. These are three basic requirements that a Software Defined Storage solution should meet. But what does this mean and how does it help you? Let me try to make some sense out of that nice three word marketing slogan:

Software Defined Storage should enable you to provision workloads to a pool of virtualized physical resources based on service level agreements (defined in a policy) in an automated fashion.

I understand that is a mouth full, so lets elaborate a bit more. Think about the challenges I described above… or what Jason described with regards to “VMs per Volume” and how there are various different components that can impact your service level. A Software Defined Storage (SDS) solution should be able to intelligently place virtual disks (virtual machines / vApps) based on selected policy for the object (virtual disk / machine / appliance). These policies typically contain characteristics of the provided service level. On top of that a Software Defined Storage solution should take risks / constraints in to account. Meaning that you don’t want your workload to be deployed to a volume which is running out of disk space for instance.

What about those characteristics, what are those? Characteristics could be anything, just two simple examples to make it a bit more obvious:

  • Does your application require recover-ability after a disaster? –> SDS selects destination which is replicated, or instructs storage system to create replicated object for the VM
  • Does your application require a certain level of performance? –> SDS selects destination that can provide this performance, or instructs storage system to reserve storage resources for the VM

Now this all sounds a bit vague, but I am purposely trying to avoid using product or feature names. Software Defined Storage is not about a particular feature, product or storage system. Although I dropped the word policy, note that enabling Profile Driven Storage within vCenter Server does not provide you a Software Defined Storage solution. It shouldn’t matter either (to a certain extent) if you are using EMC, NetApp, Nimbus, a VMware software solution or any of the other thousands of different storage systems out there. Any of those systems, or even a combination of them, should work in the software defined world. To be clear, in my opinion (today) there isn’t such a thing as a Software Defined Storage product, it is a strategy. It is a way of operating that particular part of your datacenter.

To be fair, there is a huge difference between various solutions. There are products and features out there that will enable you to build a solution like this and transform the way you manage your storage and provision new workloads. Products and features that will allow you to create a flexible offering. VMware has been and is working hard to be a part of this space, vSphere Replication / Storage DRS / Storage IO Control / Virsto / Profile Driven Storage are part of the “now”, but just the beginning… Virtual Volumes, Virtual Flash and Distributed Storage have all been previewed at VMworld and are potentially what is next. Who knows what else is in the pipeline or what other vendors are working on.

If you ask me, there are exciting times ahead. Software Defined Storage is a big part of the Software Defined Data Center story and you can bet this will change datacenter architecture and operations.

** There are two excellent articles on this topic the first by Bill Earl, and the second by Christos Karamanolis, make sure to read their perspective. **

Write-Same vs XCopy when using Storage vMotion

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I had a question last week about Storage vMotion and when Write-same vs XCopy was used. I was confident I knew the answer, but I figured I would do some testing. So what was the question exactly and the scenario I tested?

Imagine you have a virtual machine with a “lazy zero thick disk” and an “eager zero thick” disk. When initiating a Storage vMotion while preserving the disk format, would the pre-initialized blocks in the “eager zero thick” disk be copied through XCopy or would “write-same” (aka zero out) be used?

So that is what I tested. I created this virtual machine with two disks of which one being thick and about half filled and the other “eager zero thick”. I did a Storage vMotion to a different datastore (same format as source) and checked esxtop while the migration was on going:

CLONE_WR = 21943
ZERO = 2

In other words, when preserving the disk format the “XCopy” command (CLONE_WR) is issued by the hypervisor. The reason for this is when doing a SvMotion and keeping the disk formats the same the copy command is initiated for a chunk but the hypervisor doesn’t read the block before the command is initiated to the array. Hence the reason the hypervisor doesn’t know these are “zero” blocks in the “eager zero thick” disk and goes through the process of copy offload to the array.

Of course it would interesting to see what happens if I tell during the migration that all disks will need to become “eager zero thick”, remember one of the disks was “lazy zero thick”:

CLONE_WR = 21928
ZERO = 35247

It is clear that in this case it does zero out the blocks (ZERO). As there is a range of blocks which aren’t used by the virtual machine yet the hypervisor ensures these blocks are zeroed so that they can be used immediately when the virtual machine wants to… as that is what the admin requested “eager zero thick” aka pre-zeroed.

For those who want to play around with this, check esxtop and then the VAAI stats. I described how-to in this article.

How to disable Datastore Heartbeating

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I have had this question multiple times now, how do I disable datastore heartbeating? Personally, I don’t know why you would ever want to do this… but as multiple people have asked I figured I would write it down. There is no “disable” button unfortunately, but there is a work-around. Below are the steps you need to take to disable datastore heartbeating.

vSphere Client:

  • Right Cluster object
  • Click “Edit Settings”
  • Click “Datastore Heartbeating”
  • Click “Select only from my preferred datastores”
  • Do not select any datastores

Web Client:

  • Click “Cluster object”
  • Click “Manage” tab
  • Click “vSphere HA”
  • Click “Edit button” on the right side
  • Click “Datastore Heartbeating”
  • Click “Select only from my preferred datastores”
  • Do not select any datastores

It is as simple as that… However, let me stress that this is not something that I would recommend doing. Only when you are troubleshooting and need it disabled for whatever reason, please make sure to enable it when you are done.