XenServer 7.1: The Xen of Accelerating Infrastructure Strategy?
XenServer 7.1 is available: you can download it now. When XenServer 7.0 was released it had a slew of never-seen-before features, significant performance improvements and a mission; to build on Citrix's Infrastructure Strategy and provide a platform to avoid additional VMware license costs (dubbed the vTax).
That said, there was a wobble with the minor issue of major data loss, but at least it was found at patched quickly. It could be said that XenServer has a Sisyphean task to present the hypervisor as a trusted platform, as a platform that expands beyond hosting the VMs for EUC workloads to be a core provider for any workload.
To properly address resolving the perception of vTax, you need to build on features, and ensure that performance and reliability closely matches alternatives. Ideally better leverage the fact that Citrix should be best able to create value through innovation and integration within their own stack.
XenServer 7.1 was announced in January. Now it is here, what is new with XenServer 7.1? How does it compare to previous releases, and what has ceased to be? Most importantly, what does the XenServer 7.1 release do for existing, and prospective customers?
Citrix XenServer 7.1 - Updates?
First of all, there's a quite a lot of new features, and some important license and service impacts. But, ultimately not the significant performance and layout changes from 6.5 to 7 so likely that's the reason for a full on v8. Which is a pity because there is some big stuff in 7.1 which the monikur "minor release" doesn't do justice.
For XS7 I split the features into standard and enterprise, which I'll do again. But, with the XenServer 7.1 release if you've XenDesktop/XenApp licenses it was announced XenApp and XenDesktop customers are entitled to all of the features of XenServer Enterprise edition, regardless of their XenApp or XenDesktop license type. That's a pretty impressive step. You may still see the same license specification:
However, I am reliably informed, from an impeccable resource, that all of the top three options will result in the same set of features being enabled.. Note that you should upgrade their Citrix License Server to version 188.8.131.52 or higher in order to use the XenServer 7.1 licensed features and I'd anticipate a current license.
Generally Available XenServer 7.0 Updates
- Long Term Service Release (LTSR): As a Long Term Service Release, XenServer 7.1 is available with a 10-year servicing option, comprised of 5 years of standard support, plus an optional 5 years of extended support. For those thinking that XS is on its way out, that is an undeniable commitment. Click here for more info on Citrix LTSR Options
- Performance Improvements There is talk of significant reduction in the time taken for VM Import/Export operations Where I'm from in the world, there was a great anchor man on local news called Mike Neville: so great there was a song If Mike Neville Says it It Must Be True. I'd punt the same could be said (in XenServer terms) of Tobias Kreidl (although I'm unaware of his own song) who reported he'd found an x2 improvement for exports and an x1 improvement for imports. Good stuff
- Platform Updates: Xen hypervisor goes to v4.7.1; Dom0 gets Linux Kernel v4.4 - so that's nice and up-to-date.
- XenCenter Improvements: you now have the ability to change the Control Domain (Dom0) memory using XenCenter - which is a lot less faff than dropping to a command line.
- Support for New Guests: Windows Server 2016 - proper release, no more tech preview;SLES 11 SP4; CentOS 6.8, 7.3; RHEL 6.8, 7.3 ; Oracle Linux 6.8, 7.3 ; Scientific Linux 6.8; NeoKylin Linux Advance Server 6.5; NeoKylin Linux Advance Server 7
- New Processor Support: Intel Skylake-H processor. Woop.
- XenServer Nutanix Integration - Always nice to see HCI vendors put XenServer on their roadmap. XS 7.1 has updates to make use of features available within the Nutanix AOS 5.0 Tech Preview release, to enable Nutanix customers to leverage the unique capabilities of XenServer.
- Localization Support: The localized version of XenCenter (Simplified Chinese and Japanese) is also available in this release. I know, working for Atlantis Computing who as an HCI and SDS vendor have worked for a number of years with XenServer, that XS is very popular in Asia - so go that.
Enterprise Feature XenServer 7.0 Updates
- PVS Accelerator: We talked at the top how XenServer's value can be better realised with tighter integration: you could argue this has been available with Intellicache yet, the XenServer and Citrix XenApp/XenDesktop development teams have jointly developed the Provisioning Services (PVS) 7.13 solution to maximize the benefits customers receive from their Citrix Application and Desktop Delivery solutions. The new PVS-Accelerator feature is designed to reduce network traffic in XenApp and XenDesktop deployments in order to achieve greater virtual server and desktop density, faster boot times during boot storms, and overall improved server and desktop performance. This feature is available when PVS 7.13 is used in conjunction with XenServer 7.1. Effectively, the PVS image is cached locally on the VM's XenServer. There are ever evolving notes on deploying PVS Accelerator. At Synergy 2016 I came across a similar tool from a vendor in Japan - essentially providing a cache distribution of the gold image: but, this implementation is a first of its type and unique at a hypervisor level. The fun will be in consistency and availability. This should reduce the demand on PVS servers and have faster read times at scale: although still working on figures on that - will report back. If you want to know more about it - here's useful video.
- Automated Updates Using XenCenter: The Install Update wizard in XenCenter has got a whole lot smarter, automatically determining which hotfixes are required to bring a pool up-to-date and enabling customers to update multiple pools in a single pass of the wizard. It sounds very cool. I've updated many pools in the past: at worst arduous would be the most family friendly term I could employ. By it's nature, its a bugger to validate - but I look forward to its success.
- XenServer Live Patching. Let's start with quite simply, this is cool. In an industry-first, XenServer delivers the ability to seamlessly apply patches to a running system without requiring host reboots. This is impressive. Working in the HCI vendor space - it gives even greater simplicity for those customers who bought into HCI for simplicity. Yet, obviously, all the caveats and concerns for automated updates apply. I like this, the proof will be in the pudding.
- Performance Improvements: Improved SMB performance..they say, I've not seen stats to confirm as yet: on the bright side at least they didn't say CIFS.
- XenServer Conversion Manager Updates: Ability to convert VMs running on VMware ESXi and vSphere hosts; Support for converting Linux guest operating systems
XenServer 7.1 Licensing
XenServer 7.1 allows you to run in an "unlicensed" state; however, you will not have access to all possible features, and you will not be eligible for direct Citrix Support. Also, note that mixed pools of licensed and unlicensed hosts will behave as if all hosts were unlicensed.
XenServer 7.1, as with 7.0, is available in two commercial editions: Standard and Enterprise. Licensing is determined on a cost-per-socket model.
From 7.1, if you've bought XenApp or XenDesktop you're entitled to all of the features of XenServer Enterprise edition, regardless of your XenApp or XenDesktop license type. Prior to 7.1, only XenApp and XenDesktop Platinum customers were eligible for the in-memory read caching feature but, with XenServer 7.1, this feature is available to all XenApp and XenDesktop customers; XenServer simply recognises your XenApp or XenDesktop licenses and unlocks the full security and performance capabilities of XenServer 7.1.
The following table gives a comparison of features between 6.5 and 7.0 options - feel free to check the homework with the XenServer 7.1 Feature Matrix:
with Platinum XA/XD
|64-bit Xen Hypervisor|
|Long Term Service Release (LTSR)||N/A||N/A||N/A||N/A|
|Multi-Server Management with XenCenter GUI|
|Active Directory Integration|
|Role based administration and auditing|
|Dynamic Memory Control|
|Performance Reporting and Alerting|
|Live VM Migration with XenMotion|
|Automated Updates via XenCenter||N/A||N/A||N/A||N/A||$|
|XenServer Conversion Manager||N/A||N/A||N/A||N/A|
|Mixed Resource Pools with CPU Masking|
|GPU Pass-through for Desktop Graphics (AMD,NVIDIA)|
|GPU Virtualisation (vGPU)||$|
|Intellicache for XenDesktop Storage Optimisation|
|MCS Read Cache||$|
|OpenFlow capable distributed virtual switch|
|VMware vSphere to XenServer Conversion Utilities|
|Support for Intel TXT||N/A||N/A|
|Hotfix Deployment Using XenCenter|
|Dynamic Workload Balancing & Audit Reporting|
|Export Pool Resource List|
|Docker Container Management||N/A||N/A||N/S||@|
|Direct Inspecg APIs||N/A|
|SCOM Management Pack||N/A||Platinum Only||$|
|Support & Maintenance|
N/A - not applicable; N/S Not Supported; @ - not available with XenApp/XenDesktop entitlements; $ - Not in Free/Standard Editions;
If you're running vSphere for XenDesktop or Xenapp workloads, unless you're getting the hypervisor for free, definitely worth considering saving some money and hosting those workloads on XenServer.
For more information on Citrix XenServer 7.1 licensing - read the XenServer 7.1 Licensing FAQ.
XenServer 7.1 - Features over performance
XenServer 7.0 had a significant overhaul in order to deliver on improved performance. There was the introduction of control groups (or cgroups), improvements in queuing, and improvements that meant adding CPU resource to dom0 improved performance rather than degraded it.
7.1 has new features, and tweaks for performance improvements, but I couldn't spot a key config limit change. How does this actually stack up as a difference between Citrix XenServer 7.0/7.1 and Citrix XenServer 6.5/6.2?
|Virtual Machine Limits|
|Virtual CPUs per VM||16||
|Memory RAM per VM||128GB||192GB||1.5TB||1.5TB|
|Virtual Disk Images (VDI) (including CD-ROM) per Virtual Machine||7||16||255||255|
|Virtual CD-ROM drives per Virtual Machine||1||1||1||1|
|Virtual Disk Size (NFS)||2TB minus 4MB||2TB minus 4MB||2TB minus 4MB||2TB minus 4MB|
|Virtual Disk Size (LVM)||2TB minus 4MB||2TB minus 4MB||2TB minus 4MB||2TB minus 4MB|
|Virtual NICs per Virtual Machine||7||7||7||7|
|Logical processors per host||160||160||288||288|
|Concurrent protected VMs per host with HA enabled||500||500||500||500|
|Concurrent VMs per host||500 (Windows VMs) / 650 Linux (VMs)||1000||1000||1000|
|RAM per host||1TB||1TB||5TB||5TB|
|Concurrent active virtual discs per host||512||2048||4096||4096|
|Physical NICs per host||16||16||16||16|
|Physical NICs per network bond||4||4||4||4|
|Virtual NICs per host||512||512||512||512|
|VLANs per host||800||800||800||800|
|Network Bonds Per Host||4||4||4||4|
|GPUs Per Host||12||12||12||12|
|Virtual GPU VMs per host||N/A||96||128||128|
|Paths to a LUN||8||8||8||8|
|Multipathed LUNs per host||150||256||256||256|
|Multipathed LUNs per host (used by storage repositories)||75||256||256||256|
|VMs per SR||600||600||
20000 (NFS,SMB,EXT) or
20000 (NFS,SMB,EXT) or
|Resource Pool Limits|
|Hosts per resource pool||16||16||16||16|
Minor point revision - so "none": unless you're the type of wag who would consider "XA/XD license restrictions" a "feature".
Citrix XenServer 7.1- Should I go there?
XenServer 7.0 demonstrated a radical change. There was improved performance increasing VM density, vGPU and storage performance, increased networking performance. But also, with the introduction of the Direct Inspect API, Citrix showed a renewed interest in the hypervisor by delivering a genuine never-seen-before-anywhere feature. While it is still early for this feature both in terms of full functionality and people having a chance to have a proper poke at it, with XenServer 7.0 ,Citrix showed a bold and committed direction.
At a feature level, 7.1 builds well on that new foundation. With the LTSR of 7.1 you now have up to 10 years of support (5 years mainstream and 5 years of extended support) which makes it the only hypervisor to have product lifecycle dates fully aligned with Citrix XenApp and XenDesktop. This could simplify infrastructure maintenance for customers choosing to deploy a full Citrix solution where they are managing the stack. People are still getting their heads around the PVS Accelerator - but it joins Intellicache and MCS Caching to show enhanced integration and complimentary technologies that should sweeten the concept of using XenServer as the hypervisor to drive your XenDesktop/XenApp infrastructure. Even more so with the new XA/XD licensing options opening up all XS features.
However, performance and reliability are far more important that integration gimicks. The introduction of live patching will need to be proven for a lot of people, but the delivery would be a significant reliability improvement: especially when integrated with auto-updating and the Insight health check functionality that was introduced in XenServer 7.
At Summit in 2017, Citrix announced the HCI Workspace Appliance Initiative, with Hewlett Packard Enterprise (HPE) and Atlantis Computing stepping forward as the first partners to join the program. HCI solutions help to reduce complexity and cost at the hardware and storage layers, particularly for the mid-market - and having tools to ensure the hypervisor is current and stable greatly assist in the delivery of that "reduced complexity and cost".
Performance has improved in 7.1 for key areas of export/import and SMB - but there is room for improvement - especially in terms of networking for 10Gb services. That additional performance and reliability will be key to not only deliver on features that drive desktop and application delivery workloads, but to drive credentials to support server and application hosting workloads.
Given the LTSR status, given the new update functionality, given the new license options for XenDesktop/XenApp deployments - if you have XenServer there are great advantages in moving to 7.1. If you're on other hypervisors - by all means baseline your current environment and then consider an comparison - XenServer 7.1 is providing a feature rich platform that should be easier to manage from a patch maintenance point of view, understanding the density and performance comparisons should build a business case for migration.