vSphere HA and VMs per Datastore limit!

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!

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.

Awesome VSAN contest results

Every once in a while I have someone asking me how about VSAN scale? Typically the question is triggered by a conversation had with another storage vendor and either a misunderstanding or pure FUD that was spread. It is nice to see some of our beta testers showing the possibilities with VSAN. How about the result of the Miami VMUG? These guys managed to get their hands on 3 awesome Dell R720xd hosts and found someone willing to host them. Then they started building, and it didn’t take them long to figure out what the limit was on a 3 node cluster… They managed to run 2250 virtual machines on 3 hosts. Yes, that is indeed more than two thousand virtual machines.

Thanks Miami VMUG for going all out.

Building a hyper-converged platform using VMware technology part 2

In part 1 of “Building a hyper-converged platform using VMware technology” I went through the sizing and scaling exercise. In short to recap, in order to run 100 VMs we would need the following resources:

  • 100 x 1.5 vCPUs = ~30 cores
  • 100 x 5 GB = 500GB of memory
  • 100 x 50 GB (plus FTT etc) = 11.8 TB of disk space

From a storage perspective 11.8 TB is not a huge amount, 500 GB of memory can easily fit in a single host today, and 30 cores… well maybe not easilyin a single host but it is no huge requirement either. What are our options? Lets give an example of some server models that fall into the category we are discussing:

  • SuperMicro Twin Pro – 2U chassis with 4 nodes. Per node: Capable of handling 6 * 2.5″ drives and on-board 10GbE. Supports the Intel E-2600 family and up to 1TB of memory
    • SuperMicro is often used by startups, especially in the hyperconverged space but also hybrid storage vendors like Tintri use their hardware. Hey SuperMicro Marketing Team, this is something to be proud of… SuperMicro powers more infrastructure startups than anyone else probably!
    • Note you can select 3 different disk controller types, LSI 3108, LSI 3008 and the Intel C600. Highly recommend the LSI controllers!
  • HP Sl2500t – 2U chassis with 4 nodes. Per node: Capable of handling 6 * 2.5″ or 3 * 3.5″ drives and FlexibleLOM 10GbE can be included. Supports the Intel E-2600 family and up to 512GB of memory
    • You can select from the various disk controllers HP offers, do note that today there are a limited number of controllers certified.
    • Many probably don’t care, but the HP kit just looks awesome :)
  • Dell C6000 series – 2U chassis with 4 nodes. Per node: Capable of handling 6 * 2.5″ per node or 3 * 3.5″ drives. Supports the Intel E-2600 family and up to 512GB of memory
    • Note there is no on-board 10GbE or “LOM” type of solution, you will need to add a 10GbE PCIe card.
    • Dell offers 3 different disk controllers including the LSI 2008 series. Make sure to check the HC.

First thing to note here is that all of the configuration above by default come with 4 nodes, yes you can order them with less but personally I wouldn’t recommend that. Strange thing is that in order to get configuration details for the Dell and HP you need to phone them up, so lets take a look at the SuperMicro Twin Pro as there are details to be found online. What are our configuration options? Well plenty I can tell you that. CPUs ranging low-end Quad-core 1.8GHz up to Twelve-core 2.7 GHz Intel CPUs. Memory configurations ranging from 2GB DIMMS to 32GB DIMMS including the various speeds. Physical disks ranging from 250GB 7200 RPM SATA Seagate to 1.2TB 10k RPM SAS Hitachi drives. Unlimited possibilities, and that is probably where it tends to get more complicated. [Read more...]

Building a hyper-converged platform using VMware technology part 1

I have been working on a slidedeck lately that explains how to build a hyper-converged platform using VMware technology. Of course it is heavily focusing on Virtual SAN as that is one of the core components in the stack. I created the slidedeck based on discussions I have had with various customers and partners who were looking to architect a platform for their datacenters that they could easily repeat. A platform which had a nice form factor and allowed them to scale out and up. Something that could be used in a full size datacenter, but also in smaller SMB type environments or ROBO deployments even.

I guess it makes sense to start with explaining what hyper-converged means to me, although I already wrote various articles on this topic a while back. I explicitly say “to me” as I am sure many folks will have a different opinion on this. A hyper-converged platform is an appliance type of solution where a single box provides a platform for virtual machines. This box typically contains multiple generic x86 hosts (trying to avoid using the word commodity) on which a hypervisor is installed, local storage which is aggregated in to a large shared pool, and network ports. Note that typically network switching is not included in the box itself, well except for virtual switches. In order to aggregate storage in to a large shared pool an additional piece of software is required. Typical examples of hyper-converged platforms which are out there today are Nutanix, SimpliVity and Pivot .

The question than arises if these are “just” x86 boxes with hypervisors installed and storage software, what are the benefits over a regular environment? Those benefits in my opinion are:

  • Time to market is short, < 4hrs to install / deploy (probably much faster for the majority)
  • Easy of management and integration
  • Scale out, both capacity and performance wise
  • Typically more affordable (results will vary)

Sounds like a done deal right? Easier, cheaper and faster… It is fair to say that these are great solutions for many companies as they provide you with one throat to choke. With that meaning it is a single SKU offering and which includes a single point of contact for support in most cases. Only downside I have heard from some partners and customers is that these solutions are typically tied to hardware and specific configurations, which is not always the same as your preferred supplier and probably not the exact configuration you prefer. This could lead to operational challenges when it comes to updating / patching, which probably doesn’t make the operational team happy. On top of that there is the “trust” issue. Some people swear by HP and would never ever want to touch any other brand, while others won’t come close to it. That is a matter of experience and personal taste I guess. Where is all of this leading to? Well here is, in my opinion, where Virtual SAN / VSAN comes in. [Read more...]