Yellow Bricks

by Duncan Epping

vSphere

vSphere 6.5 what’s new – DRS

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Most of us have been using DRS for the longest time. To be honest, not much has changed over the past years, sure there were some tweaks and minor changes but nothing huge. In 6.5 however there is a big feature introduced, but lets just list them all for completeness sake:

  • Predictive DRS
  • Network-Aware DRS enhancements
  • DRS profiles

First of all Predictive DRS. This is a feature that the DRS team has been working on for a while. It is a feature that integrates DRS with VROps to provide placement and balancing decisions. Note that this feature will be in Tech Preview until vRealize Operations releases their version of vROPs which will be fully compatible with vSphere 6.5, hopefully sometime in the first half of next year. Brian Graf has some additional details around this feature here by the way.

Note that of course DRS will continue to use the data provided by vCenter Server, it will on top of that however also leverage VROps to predict what resource usage will look like, all of this based on historic data. You can imagine a VM currently using 4GB of memory (demand), however every day around the same time a SQL Job runs which makes the memory demand spike up to 8GB. This data is available through VROps now and as such when making placement/balancing recommendations this predicted resource spike can now be taken in to consideration. If for whatever reason however the prediction is that the resource consumption will be lower then DRS will ignore the prediction and simply take current resource usage in to account, just to be safe. (Which makes sense if you ask me.) Oh and before I forget, DRS will look ahead for 60 minutes (3600 seconds).

How do you configure this? Well that is fairly straight forward when you have VROps running, go to your DRS cluster and click edit settings and enable the “Predictive DRS” option. Easy right? (See screenshot below) You can also change that look ahead value by the way, I wouldn’t recommend it though but if you like you can add an advanced setting called ProactiveDrsLookaheadIntervalSecs.

One of the other features that people have asked about is the consideration of additional metrics during placement/load balancing. This is what Network-Aware DRS brings. Within Network IO Control (v3) it is possible to set a reservation for a VM in terms of network bandwidth and have DRS consider this. This was introduced in vSphere 6.0 and now with 6.5 has been improved. With 6.5 DRS also takes physical NIC utilization in to consideration, when a host has higher than 80% network utilization it will consider this host to be saturated and not consider placing new VMs.

And lastly, DRS Profiles. So what are these? In the past we’ve seen many new advanced settings introduced which allowed you to tweak the way DRS balanced your cluster. In 6.5 several additional options have been added to the UI to make it easier for you to tweak DRS balancing, if and when needed that is as I would expect that for the majority of DRS users this would not be the case. Lets look at each of the new options:

So there are 3 options here:

  • VM Distribution
  • Memory Metric for Load Balancing
  • CPU Over-Commitment

If you look at the description then I think they make a lot of sense. Especially the first two options are options I get asked about every once in a while. Some people prefer to have a more equally balanced cluster in terms of number of VMs per host, which can be done by enable “VM Distribution”. And for those who much rather load balance on “consumed” vs “active” memory you can also enable this. Now the “consumed” vs “active” is almost a religious debate, personally I don’t see too much value, especially not in a world where memory pages are zeroed when a VM boots and consumed is always high for all VMs, but nevertheless if you prefer you can balance on consumed instead. Last is the CPU Over-Commitment, this is one that could be useful when you want to limit the number of vCPUs per pCPU, apparently this is something that many VDI customers have asked for.

I hope that was useful, we are aiming to update the vSphere Clustering Deepdive at some point as well to include some of these details…

What is new for Virtual SAN 6.5?

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As most of you have seen by the explosion of tweets, Virtual SAN 6.5 was just announced. Some may wonder how 6.5 can be announced so fast after the Beta Announcement, well this is not the same release. This release has a couple of key new features, lets look at those:

  • Virtual SAN iSCSI Service
  • 2-Node Direct Connect
    • Witness Traffic Separation for ROBO
  • 512e drive support

Lets start with the biggest feature of this release, at least in my opinion, Virtual SAN iSCSI Service. This provides what you would think it provides: the ability to create iSCSI targets and LUNs and expose those to the outside world. These LUNs by the way are just VSAN objects, and these objects have a storage policy assigned to them. This means that you get iSCSI LUNs with the ability to change performance and/or availability on the fly. All of it through the interface you are familiar with, the Web Client. Let me show you how to enable it:

  • Enable the iSCSI Target Service
  • Create a target, and a LUN in the same interface if desired
  • Done

How easy is that? Note that there are some restrictions in terms of use cases. It is primarily targeting physical workloads and Oracle RAC. It is not intended for connecting to other vSphere clusters for instance. Also, you can have a max of 1024 LUNs per cluster and 128 targets per cluster at most. LUN capacity limit is 62TB.

Next up on the list is 2-node direct connect. What does this mean? Well it basically means you can now cross-connect two VSAN hosts with a simple ethernet cable as shown in the diagram in the right. Big benefit of course is that you can equip your hosts with 10GbE NICs and get 10GbE performance for your VSAN traffic (and vMotion for instance) but don’t incur the cost of a 10GbE switch.

This can make a huge difference when it comes to total cost of ownership. In order to achieve this though you will also need to setup a separate VMkernel interface for Witness Traffic. And this is the next feature I wanted to mention briefly. For 2-node configurations it will be possible as of VSAN 6.5 to separate witness traffic by tagging a VMkernel interface as a designated witness interface. There’s a simple “esxcli” command for it, note that <X> needs to be replaced with the number of the VMkernel interface:

esxcli vsan network ip set -i vmk<X> -T=witness

Then there is the support for 512e drives, note that 4k native is not supported at this point. Not sure what more to say about it than that… It speaks for itself.

Oh and one more thing… All-Flash has been moved down from a licensing perspective to “Standard“. This means anyone can now deploy all-flash configuration at no additional licensing cost. Considering how fast the world is moving to all-flash I think this only makes sense. Note though that data services like dedupe/compression/raid-5/raid-6 are still part of VSAN Advanced. Nevertheless, I am very happy about this positive licensing change!

vSphere 6.5 what’s new – VMFS 6 / Core Storage

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I haven’t spend a lot of time looking at VMFS lately. I was looking in to what was new for vSphere 6.5 and then noticed a VMFS section. Good to see there is still being worked on new features and functionality for the core vSphere file system. So what is new with VMFS 6:

  • Support for 4K Native Drives in 512e mode
  • SE Sparse Default
  • Automatic Space Reclamation
  • Support for 512 devices and 2000 paths (versus 256 and 1024 in the previous versions)
  • CBRC aka View Storage Accelerator

Lets look at them one by one, I think support for 4K native drives in 512e mode speaks for itself. Sizes of spindles keep growing and these new “advanced format” drives come with a 4K byte sector instead of the usual 512 byte sector, which is primarily for better handling of media errors. As of vSphere 6.5 this is now fully supported but note that for now it is only supported when running in 512e mode! The same applies to Virtual SAN in the 6.5 release, only supported in 512e mode. This basically means that 512 byte sectors is being emulated on a 4k drive. Hopefully we will have more on full support for 4Kn for vSphere/VSAN soon.

From an SE Sparse perspective, right now SE Sparse is used primarily View and for LUNs larger than 2TB. When on VMFS 6 the default will be SE Sparse. Not much more to it than that. If you want to know more about SE Sparse, read this great post by Cormac.

Automatic Space Reclamation is something that I know many of my customers have been waiting for. Note that this is based on VAAI Unmap which has been around for a while and allows you to unmap previously used blocks. In other words, storage capacity is reclaimed and released to the array so that when needed other volumes can use these blocks. In the past you needed to run a command to reclaim  the blocks, now this has been integrated in the UI and can simply be turned on or off. Oh, you can find this in the UI when you go to your datastore object and then click configure, you can set it to “none” which means you disable it, or you set it to low in the UI as shown in the screenshot below.

If you prefer “esxcli” then you can do the following to get the info of a particular datastore (sharedVmfs-0 in my case) :

esxcli storage vmfs reclaim config get -l sharedVmfs-0
   Reclaim Granularity: 1048576 Bytes
   Reclaim Priority: low

Or set the datastore to a particular level, note that using esxcli you can also set the priority to medium and high if desired:

esxcli storage vmfs reclaim config set -l sharedVmfs-0 -p high

Next up, support for 512 Devices and 2000 Paths. In previous versions the limit was 256 devices and 1024 paths and some customers were hitting this limit in their cluster. Especially when RDMs are used or people have a limited number of VMs per datastore, or maybe 8 paths to each device are used it becomes easy to hit those limits. Hopefully with 6.5 that will not happen anytime soon. On the other hand, personally I would hope more and more people are considering moving towards either VSAN or Virtual Volumes.

This is one I accidentally ran in to and not really directly related to VMFS but I figured I would add it here anyway otherwise I would forget about it. In the past CBRC aka View Storage Accelerator was limited to 2GB of memory cache per host. I noticed in the advanced settings that it now is set to 32GB, which is a big difference compared to the 2GB in previous releases. I haven’t done any testing, but I assume our EUC team has and hopefully we will see some good performance data on this big increase soon.

And that was it… some great enhancements in the core storage space if you ask me. And I am sure there was even more, and if I find out more details I will share those with you as well.

Hyper-Converged is here, but what is next?

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Last week I was talking to a customer and they posed some interesting questions. What excites me in IT (why I work for VMware) and what is next for hyper-converged? I thought they were interesting questions and very relevant. I am guessing many customers have that same question (what is next for hyper-converged that is). They see this shiny thing out there called hyper-converged, but if I take those steps where does the journey end? I truly believe that those who went the hyper-converged route simply took the first steps on an SDDC journey.

Hyper-converged I think is a term which was hyped and over-used, just like “cloud” a couple of years ago. Lets breakdown what it truly is: hardware + software. Nothing really groundbreaking. It is different in terms of how it is delivered. Sure, it is a different architectural approach as you utilize a software based / server side scale-out storage solution which sits within the hypervisor (or on top for that matter). Still, that hypervisor is something you were already using (most likely), and I am sure that “hardware” isn’t new either. Than the storage aspect must be the big differentiator right? Wrong, the fundamental difference, in my opinion, is how you manage the environment and the way it is delivered and supported. But does it really need to stop there or is there more?

There definitely is much more if you ask me. That is one thing that has always surprised me. Many see hyper-converged as a complete solution, reality is though that in many cases essential parts are missing. Networking, security, automation/orchestration engines, logging/analytic engines, BC/DR (and orchestration of it) etc. Many different aspects and components which seem to be overlooked. Just look at networking, even including a switch is not something you see to often, and what about the configuration of a switch, or overlay networks, firewalls / load-balancers. It all appears not to be a part of hyper-converged systems. Funny thing is though, if you are going on a software defined journey, if you want an enterprise grade private cloud that allows you to scale in a secure but agile manner these components are a requirement, you cannot go without them. You cannot extend your private cloud to the public cloud without any type of security in place, and one would assume that you would like to orchestrate every thing from that same platform and have the same networking / security capabilities to your disposal both private and public.

That is why I was so excited about the VMworld US keynote. Cross Cloud Services on top of hyper-converged leveraging all the tools VMware provides today (vSphere, VSAN, NSX) will exactly allow you to do what I describe above. Whether that is to IBM, vCloud Air or any other of the mega clouds listed in the slide below is even besides the point. Extending your datacenter services in to public clouds is what we have been talking about for a while, this hybrid approach which could bring (dare I say) elasticity. This is a fundamental aspect of SDDC, of which a hyper-converged architecture is simply a key pillar.

Hyper-converged by itself does not make a private cloud. Hyper-converged does not deliver a full SDDC stack, it is a great step in to the right direction however. But before you take that (necessary) hyper-converged step ask yourself what is next on the journey to SDDC. Networking? Security? Automation/Orchestration? Logging? Monitoring? Analytics? Hybridity? Who can help you reach full potential, who can help you take those next steps? That’s what excites me, that is why I work for VMware. I believe we have a great opportunity here as we are the only company who holds all the pieces to the SDDC puzzle. And with regards to what is next? Deliver all of that in an easy to consume manner, that is what is next!

 

 

 

Want to watch a VMworld 2016 session?

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I had a long discussion with the VMworld team about this the past editions and I am happy to say that ALL sessions have been made available to the public straight after the event. VMware made all VMworld 2016 session available to the public. You can find them here: http://www.vmworld.com/en/sessions/2016.html. And also, if you want a more “limited” list, you can go for the top ranked sessions. You can find the top-10 session of each VMworld day here: http://www.vmworld.com/en/sessions/top-10-us.html.

There is one session I want to call out, I wasn’t able to do a live blog on it, mainly because it went deep, and it went deep fast. Ravi R. is one of the best deep tech speakers I have seen: INF8108 – Extreme Performance Series: vCenter Performance Deep Dive.

Thanks VMworld team for doing this. Time for some binge watching 🙂