Archives for September 2014


Fast Access with PreLaunch and Session Linger in Citrix XenApp 7.6

Session lingering seems like a great fit shared environments like schools and hospitals.

More info on Citrix Validated Solution for Nutanix – 1000 users in 6U of space.


Prism Element and Prism Central Walkthrough

A brief overview of the Nutanix UI and multi-cluster management. Take a look at one of the Nutanix internal engineering clusters used for quality assurance and load testing. Over 28 nodes of different sizes and product families acting as one giant cluster.

Also posted on


Nutanix and EVO:RAIL\VSAN – Data Placement

Nutanix and VSAN\EVO:RAIL are different in many ways. One such way is how data is spread out through the cluster.

• VSAN is a distributed object file system
• VSAN metadata lives with the vm, each vm has it’s own witness
• Nutanix is a distributed file system
• Nutanix metadata is global

VSAN\EVO:RAIL will break up its objects (VMDK’s) into components. Those components get placed evenly among the cluster. I am not sure on the algorithm but it appears to be capacity based. Once the components are placed on a node they stay there until:

• They are deleted
• The 255 GB component (default size) fills up and another one is created
• The Node goes offline and a rebuild happens
• Maintenance mode is issued and someone selects the evacuate data option.

So in a fresh brand new cluster things are pretty evenly distributed.


VSAN distributes data with the use of components

VSAN distributes data with the use of components

Nutanix uses data locality as the main principle in placement of all initial data. One copy is written locally, one copy remotely. As more writes occur the secondary copy of the data keeps getting spread evenly across the cluster. Reads stay local to the node. Nutanix uses extent and extent groups as the mechanism to coalesce the data (4 MB).

A new Nutanix cluster or one running for a long time, things are kept level and balanced based on a percentage of overall capacity. This method accounts for clusters with mixed nodes\needs. More here.



Nutanix places copies of data with the use of extent groups.

So you go to expand your cluster…

With VSAN after you add a node (compute, SSD, HDD) to a cluster and you vMotion workload over to the new node what happens? Essential nothing. The additional capacity would get added to the cluster but there is no additional performance benefit. The VM’s that are moved to the new node continue to hit the same resources across the cluster. The additional flash and HDD sit there idle.


Impact of adding a new node with VSAN and moving virtual machines over.

Impact of adding a new node with VSAN and moving virtual machines over.

When you add a node to Nutanix and vMotion workloads over they start writing locally and get to benefit from the additional flash resources right away. Not only is this important from a performance perspective, it also keeps available data capacity level in the event of a failure.



Impact of adding a new node with Nutanix and moving virtual machines over.

Since data is spread evenly across the cluster in the event of hard drive failing all of the nodes in Nutanix can help with rebuilding the data. With VSAN only the nodes containing the components can help with the rebuild.

Note: Nutanix rebuilds cold data to cold data (HDD to HDD), VSAN rebuilds data into the SSD Cache. If you lose a SSD with VSAN all backing HDD need to be rebuilt. The data from HDD on VSAN will flood into the cluster SSD tier and will affect performance. This is one of the reasons I believe why 13 RAID controllers were pulled from the HCL. I do find it very interesting because one of the RAID controllers pulled is one that Nutanix uses today.

Nutanix will always write the minimum two copies of data in the cluster regardless of the state of the clusters. If it can’t the guest won’t get the acknowledgment. When VSAN has a host that is absent it will write only 1 copy if the other half of the components are on the absent host. At some point VSAN will know it has written too much with only 1 copy and start the component rebuild before the 60 minute timer. I don’t know the exact algorithm here either, it’s just what I have observed after shutting a host down. I think this is one of the reasons that VSAN recommends writing 3 copies of data.

[Update: VMware changed the KB article after this post. It was 3 copies of data and has been adjusted to 2 copies (FT > 0) Not sure what changed on their side. There is no explanation for the change in the KB.]

Data locality has an important role to play in performance, network congestion and in availability.

More on Nutanix – EVO

Learn more about Nutanix


Machine Data Merged with Web-Scale. #Splunk #Nutanix #MISABC2014

Screen Shot 2014-09-15 at 10.33.27 PM

Splunk Enterprise scales to collect and index tens of terabytes of data per day. And because the insights from your data are mission-critical, Splunk software’s index replication technology provides the availability you need, even as you scale out your low-cost, distributed computing environment. Automatic load balancing optimizes workloads and response times and provides built-in failover support. Out-of-the-box reporting and analytics capabilities deliver rapid insights from your data.

Splunk DB Connect delivers reliable, scalable, real-time integration between Splunk and traditional relational databases. Splunk Hadoop Connect provides bi-directional integration to easily and reliably move data between Splunk Enterprise and Hadoop.

Learn why you should virtualize Splunk and how Nutanix and Splunk combine web-scale approaches with the likes of map-reduce to deliver insights and value from your infrastructure.

Check out the full Splunk RA on Nutanix

Check out the Nutanix speaking sessions at MISA BC


Nutanix High Availability and Continuity – Impact on Ops

One of the added benefits of scale-out storage is the addition of multiple storage controllers. When you have more than 2 storage controllers and you lose one due to failure or maintenance like a rolling upgrade, you can do so with minimal impact.

Below are the results of 8-node cluster with 700 desktops running a Login VSI medium workload. One of the 8 storage controllers is shutdown to see the impact on the cluster. No desktops were rebooted or shutdown. IOPS dropped from 2,000 to 1,496 and latency had a brief spike from 4ms to 22.37 ms.

Impact of shutting off a Nutanix Storage Controller. No vMotion for upgrades or maintenance.

Impact of shutting off a Nutanix Storage Controller. No vMotion for upgrades or maintenance.

Things to think about for hyper-convergence?

* Is data spread out evenly that additional controllers will help?
* Do you have to vMotion VM’s to preform an upgrade? If so, can you meet your maintenance window?
* Will dependences on the Hypervisor management stack cause you to patch both your control and data plane?

See more proven results on scaling with the VMware Horizon 6.0 with the View RA


Choice: vSphere Licensing on Nutanix

Nutanix provides choice on what vSphere license you can apply to your environment. If your at a remote site, you can run vSphere essentials, if you have a high density deployment you can run vSphere Enterprise Plus. In short, the choice is left up to the customer on what makes sense.

It’s important to have flexibility around licensing because VMware can add\remove packages any time. For example, VMware announced a great ROBO license edition recently, VMware vSphere Remote Office Branch Office Standard and Advanced Editions. Now you can purchase VMware licensing per packs of VM versus paying per socket. Enterprises that have lots of remote sites but few resources running in them can take a look at the NX-1020 that has native built-in replication plus the appropriate licensing pack.

Nutanix Perfect for Remote Sites

Licensing can change any time, Nutanix provides flexibility to meet your needs. Check out this great video on why vSphere for Remote Sites.

What happens if you have an existing Enterprise Licensing Agreement? No problem! Go ahead and apply your existing license. If your needs change, rest assured Nutanix will keep running.

This flexibility in licensing comes from the fact that Nutanix runs in the user space and hasn’t created any dependences on vCenter. Nutanix will continue to run without vCenter and management of your cluster is not affected by vCenter going down. The Nutanix UI known as PRISM is highly available and designed to scale right along with your cluster, from 5 VM’s to +50,000 VM’s.

Pick what works for you.


First posted on


Do you have a vCenter plugin?

vCenter Plugins are a bad proposition and fit into the bucket of “too good to be true” when talking about storage. Having your storage dependent on vCenter creates a situation where you are now tied to something that is a single point of failure, has is security implications, it can limit your design/solution due to vCenter’s lack of scale and restricts your control over future choices. In most cases storage companies have plugins because the initial setup with ESXi is complex and they are trying to mask some the work needed to get it up and running.

Single Point of Failure

Even VMware Technical marketing staff admit that vCenter is limited in options to keep it protected. Now that Heartbeat is end of life there really isn’t a good solution in place.
What happens when vCenter goes down? Do you rely on the plugin to provide UI for administration? How easy is it run commands from the CLI when the phones light up with support calls?

Nutanix ability to scale and remain availability is not dependent on a plugin.


If I was to place money, I would bet no one can write a plugin for vCenter better than VMware with security in mind. VMware has decided not to create a plugin for EVOL:RAIL and stand up a separate web server. I might be reading in between the lines but punching more holes into vCenter is not a good thing. How hardened can a 3rd party plugin be? Chances are the plugin will ending up talking to esxi hosts thru vpxuser which essential is a root account. It’s not the root account that is scary, it how people get access to it. Does the plugin use vCenter security rights? Too me there is just more questions than answers.

From the vendor side, as VMware goes from vSphere 5.5 -> 6.0 -> .Next, the plugin will have to be in lock step and will cause more work and time in making sure the plugin works versus pouring that time and effort into new development.


Scale and number nodes are affected by vCenter’s ability to manage the environment. Both cluster size and linked mode by a part in the overall management. If the plugin is needed to manage the environment can you scale past the limits of vCenter? How many additional management points does this cause? In a multi-site deployment can you use two vCenters? Experience tells me vCenter at the data center managing remote sites hasn’t been fun in the past.

If you’re a hyper-converged vendor do you have to license all of your nodes if you just need storage due to the plugin? If you just need a storage node you do have the option of just adding it to the cluster and not vCenter with Nutanix.

One of the most scariest things from an operations point of view is patching. Does patching vCenter cause issues to the plugin? Do you have to follow the HCL matrix when patching the plugin? Today patching Horizon View you have to worry about storage version, VMware Tools, View Agent, View Composer, vCenter, Database version, Anti-virus version and adding a plugin to the mix will not help.

I think vCenter plugins are over-hyped for what they can cause in return. Maybe Nutanix will get one but this kid doesn’t see the need. If the future direction is for web-based client, having another tab open in Chrome is not a big deal.


Hypervisor Agnostic Backuup -> Hyper-V -> ESXi -> AWS

Backup Everything

Cloud Connect is going GA with the release of NOS 4.1 and I did notice the new Backup checkbox when setting up Remote Sites. I just assumed it was for setting up the remote site in AWS. While it is needed for AWS it also allows you take one Nutanix Cluster running any hypervisor like Hyper-V and backup it up to another Nutanix Cluster running any Hypervisor like vSphere ESXi.

Hypervisor Agonistic

If I was to read the documentation I would have found this:

Backup: Check the box to enable backup (only) to this site. Backup allows the remote site to be used as a backup (replication) target. This means data can be backed up to this site and snapshots can be retrieved from the site to restore locally, but failover protection (that is, running failover VMs directly from the remote site) is not enabled.

Note: Remote sites can be in the same data center or in another facility, remote sites are just different physical clusters.

I can see this being is used a lot for ROBOs where Hyper-V is being used to cut costs on licensing. Customers then can use Prism Central for viewing of all their remote sites and data center clusters. All of the feel good features still work, compression and deduplication and you can mix and match model to get the best price\performance\capacity that works for you.

Nutanix is the only hyper-converged vendor that offers this flexibility and choice today.


Registry Keys for Fixing Slow Boot Times with PVS – #Xendesktop #RDS

Purely to bookmark this for myself.

reg add “HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters” /v DisableTaskOffload /t REG_DWORD /d 1 /f

reg add “HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters” /v DisableLargeSendOffload /t REG_DWORD /d 1 /f

reg add “HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters” /v EnableTCPA /t REG_DWORD /d 0 /f

reg add “HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters” /v EnableRSS /t REG_DWORD /d 0 /f

reg add “HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters” /v EnableTCPChimney /t REG_DWORD /d 0 /f

Information from Citrix Forums


esxcli system settings kernel set -s netNetqueueEnabled -v FALSE