Yellow Bricks

by Duncan Epping

virtual san

VMware Virtual SAN launch and book pre-announcement!

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Today is the day, finally… the Virtual SAN (VSAN) launch. Many people have been waiting for this one. With 12.000 plus beta participants this was one of the biggest projects I have ever seen within VMware. It is truly impressive to see how the product has grown and what the team has done. Before I will provide you with some of the details of the announcement I want to share something else that all of you should look out for:

Cormac Hogan and I decided it was time for a book on Virtual SAN. Both of us have published many articles about VSAN the last 9 months and have been working with the product for over a year now so it only made sense. We have decided, and this wasn’t an easy decision for me, to go with VMware Press. When I say “not an easy decision” I don’t want to sound negative about using publisher, but it is just that I have had a great experience (and results) with self-publishing. It was time for a new experience though, try something different. As we speak we are working hard to get the final set of chapters in for review / editing and we are hoping to have the book available before VMworld. I am guessing that the rough cuts will be available through Safari in the upcoming weeks, if so I will let you know via a blog post.

Now lets get back to the topic of the day again, Virtual SAN Launch… So what was announced today?

  • General Availability of Virtual SAN 1.0 the week of the 10th of March
  • vSphere 5.5 Update 1 will support VSAN GA
  • Support for 32 hosts in a Virtual SAN cluster
  • Support for 3200 VMs in a Virtual SAN cluster
  • Full support for VMware Horizon / View
  • Elastic and Linear Scalability for both capacity and performance
  • VSAN is not a VSA. Performance is much better than any VSA!
  • 2 Million IOPS validated in a 32 host Virtual SAN cluster
  • ~ 4.5PB in a 32 host cluster
  • 13 different VSAN Ready Node configurations between Cisco IBM Fujitsu and Dell available at GA, more coming soon!

Once again, great work by the VSAN team. Version 1.0 just got release, and I can barely wait for the next release to become available!

What is Virtual SAN really about?

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When talking about Virtual SAN you hear a lot of people talking about the benefits, what Virtual SAN is essentially about. You see the same with various other so-called Software Defined Storage solutions. People typically, when talking about these solutions, talk about things like “enabling within 2 clicks”… Or maybe about how easy it is to scale out, or scale-up for that matter. How much performance you have because of the way they use flash drives. Or about some of the advanced data services they offer.

While all of these are important, when it comes to Virtual SAN I don’t think that is the true strength. Sure, it is great to be able to provide a well performing easy to install scale-out storage solution… but the true strength in my opinion is: Policy Based Management & Integration. After having worked with VSAN for months, that is probably what stood out the most… policy based management

What does this deep integration and what do these policies allow you to do?

  • It provides the ability to specify both Performance and Availability characteristics using the UI (Web Client) or through the API.
    • Number of replicas
    • Stripe width
    • Cache reservations
    • Space reservations
  • It allows you to apply policies to your workload in an easy way through the UI (or API).
  • It provides the ability to do this in a granular way, per VMDK and not per datastore.
  • To a group of VMs or even all VMs in a programmatic way when needed.

Over the last couple of months I have played extensively with this feature of VSAN and vCenter, and in my opinion it is by far the biggest benefit of a hypervisor-converged storage solution. Deep integration with the platform, exposed in a simplistic VM-centric way through the Web Client and/or the vSphere APIs.

Virtual SAN (related) PEX Updates

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I am at VMware Partner Exchange this week and there and figured I would share some of the Virtual SAN related updates.

  • 6th of March their is an online Virtual SAN event with Pat Gelsinger, Ben Fathi and John Gilmartin… Make sure to register for it!
  • Ben Fathi (VMware CTO) stated that VSAN will be GA in Q1, more news in the upcoming weeks
  • Maximum cluster size has been increased from 8 (beta) to 16 according to Ben Fathi, VMware VSAN engineering team is ahead of schedule!
  • VSAN has linear scalability, close to a million IOPS with 16 hosts in a cluster (100% read, 4K blocks). Mixed IOPS close to half a million. All of this with less than 10% CPU/Memory overhead. That is impressive if you ask me. Yeah yeah I know, numbers like these are just a part of the overall story… still it is nice to see that this kind of performance numbers can be achieved with VSAN.
  • I noticed a tweet Chetan Venkatesh and it looks like Atlantis ILIO USX (in memory storage solution) has been tested on top of VSAN and they were capable of hitting 120K IOPS using 3 hosts, WOW. There is a white paper on this topic to be found here, interesting read.
  • It was also reinstated that customers who sign up and download the beta will get a 20% discount on the first purchase of 10 VSAN licenses or more!
  • Several hardware vendors announced support for VSAN, a nice short summary by Alberto to be found here.

vSphere HA and VMs per Datastore limit!

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I felt I would need to get this out there, as it is not something many seem to be aware off . More and more people are starting to use storage solutions which offer 1 large shared datastore, examples are solutions like Virtual SAN, Tintri and Nutanix. I have seen various folks saying: unlimited number of VMs per datastore, but of course there are limits to everything! If you are planning to build a big cluster (HA enabled), keep in mind that per cluster your limit for a datastore is 2048 powered-on virtual machines! Say what? Yes that is right, per cluster you are limited to 2048 powered-on VMs on a single datastore. This is documented in the Max Config Guide of both vSphere 5.5 and vSphere 5.1. Please note it says datastore and not VMFS or NFS explicitly, this applies to both!

The reason for this today is the vSphere HA poweron list. I described that list in this article, in short: this list keeps track of the power-state of your virtual machines If you need more VMs in your cluster than 2048 you will need to create multiple datastores for now. (More details in the blog post) Do note that this is a known limitation and I have been told that the engineering team is researching a solution to this problem. Hopefully it will be in one of the upcoming releases.

Virtual SAN Compatibility Guide updated!

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For those looking to start configuring hardware for VSAN / Virtual SAN infrastructures, the VMware Compatibility Guide just got updated!

Personally I find the new section on disk controllers very useful as it shows whether the controller is supported in SAS / SATA / RAID-0 or Pass-through. I can’t wait for the first VSAN Ready Nodes to pop-up. Note that VSAN is not GA yet, so I expect the HCL to be expanded even further over time. Just like to say: Nice work Dell, it looks you folks are really making an effort getting your hardware certified.