EVO RAIL: Status Quo for Nutanix

boatSome will make a big splash about the launch of EVO RAIL but the reality is that things remain status quo. While I do work for Nutanix and I am admittedly biased, the fact is that Nutanix as a company was formed in 2009 and has been selling since 2011. VSAN and now EVO RAIL is a validation of what Nutanix has been doing over the last 5 years. In this case, high tide lifts all boats.

Nutanix will continue to partner with VMware for all solutions, just like VDI, RDS, SRM, Server Virt, Big data applications like Splunk and private cloud. Yes we will compete with VSAN but I think the products are worlds apart mostly due to architectural decisions. Nutanix helps to sell vSphere and enable all the solutions that VMware provides today. Nutanix has various models that serve Tier 1 SQL\Oracle all the way down to the remote branch where you might want only a hand full of VM’s. Today EVO RAIL is only positioned to serve only Tier 2, Test/Dev and VDI. The presentation I sat in on as a vExpert confirmed Teir 1 was not a current use case. I do feel that this is mistake for EVO RAIL. By not being able to address Tier 1 which I would include VDI in the use case, you end up creating silos in the data center which is everything that SDDC should be trying to eliminate.

Nutanix Uses Cases

Some of the available Nutanix Uses Cases


Nutanix is still King of Scale but I am interested to hear more about EVO RACK which still in tech preview. EVO RAIL in version 1.0 will only scale to 16 nodes\servers or 4 appliances. Nutanix doesn’t really have a limit but tends to follow hypervisor limits, most Nutanix RA’s are around 48 nodes from a failure domain perspective.

Some important differences between Nutanix and EVO RAIL:

* Nutanix starts at 3 nodes, EVO RAIL starts at 4 nodes.

* Nutanix uses Hot Optimized Tiering based on data analysis and cache from RAM which can be deduped, EVO RAIL uses caching from SSD(70% of all SDD is used for cache).

* You can buy 1 Nutanix node at a time, EVO RAIL only is sold with 4 nodes at a time. Though I think this has do with trying to keep a single sku. The SMB in the market will find it had to make this jump though. On the Enterprise side you need to be able to have different node types if your compute\capacity doesn’t match up.

* Nutanix can scale with different node types ranging in different levels of storage and compute, EVO RAIL today is a hard locked configuration. You are unable to even change the amount of RAM from the OEM vendor. CPU’s are only 6 core which leads to needing more nodes = more licenses.

* EVO RAIL is only spec’d for 250 desktops\100 general server VM’s per appliance. Nutanix can deliver 440 desktops per 2U appliance with a medium Login VSI workload and 200 general server VM’s when enabling features like inline dedupe on the 3460 series. In short we have no limits if you don’t have CPU\RAM contention.


* Nutanix has 1 Storage Controller(VM) per host that takes cares of VM Cailber Snapshots, inline compression, inline Dedupe, Map Reduce Dedupe, Map Reduce compression, Analytics, Cluster Health, Replication, hardware support. EVO Rail will have a EVO management software(web server), vCenter VM, Log insight VM and a VM from the OEM Vendor for hardware support and vSphere replication VM if needed.

* Nutanix is able to have separation between compute and storage clusters. EVO RAIL is one large compute cluster with only storage container. By having separation you can have smaller compute clusters and still enjoy one giant volume. This is really just an issue of having flexibility on design.

* Nutanix can run with any license of vSphere, EVO RAIL license is Enterprise Plus. I am not sure how that will affect pricing. I suspect the OEM will be made to keep it at normal prices because if would affect the rest of their business.

* Nutanix can manage multiple large\small cluster with Prism Central. EVO RAIL has no multi-cluster management.

* Nutanix you get to use all of the available hard drives for all of the data out of the box. EVO RAIL you have to increase the stripe width to take advantage of all the available disks when data is moved from cache
to hard disk.

* Nutanix offers both Analysis and built in troubleshooting tools in the Virtual Storage Controller. You don’t have to add another VM in to provide the services.

Chad Sakac mentioned in one of his articles “my application stack has these rich protection/replication and availability SLAs – because it’s how it was built before we started thinking about CI models””, that you might not pick EVO RAIL and go to a Vblock. I disagree on the CI part. Nutanix has the highest levels of data protection today. Synchronous writes, bit rot prevention, all data is check summed, data is continuously scrubbed in low periods, Nutanix based snapshots for backup and DR.

It’s a shame that EVO RAIL went with the form factor they did. VSAN can lose up to 3 nodes at any one time which is good but in the current design it will need5 copies of data to ensure that a block going down will not cause data loss when you go to scale the solution. I think they should have stayed with a 1 node – 2 U solution. Nutanix has a feature called Availability Domains that allows us to survive a whole block going down and the cluster can still function. This feature doesn’t require any additional storage capacity to use the feature, just the minimum two copies of data.

More information on Availability Domains can be found on the Nutanix Bible


* Nutanix can Scale past 32 nodes, VSAN is supported for 32 nodes but yet EVO RAIL is only supported for 16 nodes. I don’t know why they made this decision.

* Prism Element has no limits to the number objects that it can manage. EVO RAIL is still limited by the number of components. I believe that the limited hardware specs are being used to limit the number components so this does not become an issue in the field.

* Nutanix when you add a node you can enjoy the performance benefits right away. EVO RAIL you have to wait until new VM’s are created to make use of the new flash and hard drives(or a perform a maintenance operation). Lot of this has to do on how Nutanix controls the placement of data, data locality helps with this.

I think the launch of EVO RAIL shows how important hardware still is when achieving 5 9’s of availability. Look out dual headed storage architectures, your lunch just got a little smaller again.


  1. * Nutanix uses Hot Optimized Tiering based on data analysis, EVO RAIL uses caching.

    So that’s a big plus for EVO RAIL.
    Tiering only works for static workloads. In dynamic environments with lots of different and changing workingsets it can even decrease performance.
    Caching in general is much more flexible!

    • Nutanix does have caching too but in RAM instead of SSD. Based on a dynamic threshold of how much memory you give the virtual storage controller you can assign more cache. You can also enable inline dedupe which spans the cache over memory and SSD. VSAN 70% of the SSD space is reserved for cache. Nutanix is more dynamic and cache and SSD misses get use all the local HDD instead of the default of 1 from VSAN. Also most times data will come from the local HDD and VSAN will have to pull it across the from other nodes creating unnecessary network congestion. The high amount reserved can also cause lots of eviction in mixed workload as well.

      Thanks for posting and I will make the change above.

    • Not only that: memory is the bottleneck in virtual environments nowadays. So having less memory left because it’s used for caching is a negative thing here.

      • All hyper-converged solutions today consume RAM, it’s just a matter of how much. If you have 200GB of Cache on a SAN somewhere for cache it has to come from somewhere. While VSAN doesn’t use RAM they use the View Storage Accelerator as separate way to try to deliver the same results to get around issue of data locality. VSAN does run in RAM but I haven’t seen any guidelines other min host requirements.

        The Nutanix base for storage controller VM is 16 GB of RAM, 12 GB on the 1000 series.

  2. The Pen Is Mightier says:

    Stayed with a 1 node solution? 3 nodes failures and 5 copies? Dwayne can’t even

    • Not sure I get the question. I mention 5 copies of data with VSAN because that is what it would take to surive a block failure in a large cluster today


  1. […] been a great decision on their part. Nutanix adds value in other ways that bring value, in which EVO:RAIL does not, and there are many features still in the works. Nutanix has recently raised $140M Series E from […]

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