Citrix Xenserver 6.1 – New Features! Our favorites…

Citrix Xenserver has been a great hypervisor for many years now, and continues to get better with new features and benefits that come out with every revision.  Xenserver 6.1 is no exception as it packs some powerful new features that are sure to make your life easier, and allow you more control and flexibility over your Citrix virtualization solution.  Let’s take a look at a few of them:

Storage XenMotion:

Storage XenMotion allows running VMs to be moved from one host to another. This includes the case where (a) VMs are not located on storage shared between the hosts and (b) hosts are not in the same resource pool. This enables system administrators to:

  • Rebalance or move VMs between XenServer pools – for example promoting a VM from a development environment to a production environment;
  • Perform software maintenance – for example upgrading or updating standalone XenServer hosts without VM downtime;
  • Perform hardware maintenance – for example upgrading standalone XenServer host hardware without VM downtime;
  • Reduce deployment costs by using local storage.

Live VDI Migration:

Live VDI Migration allows system administrators to relocate a VM’s Virtual Disk Image (VDI) without shutting down the VM. This enables system administrators to:

  • Move a VM from cheap, local storage to fast, resilient, array-backed storage;
  • Move a VM from a development to a production environment;
  • Move between tiers of storage when a VM is limited by storage capacity;
  • Perform storage array upgrades.

Networking Enhancements

  • Link Aggregation Control Protocol (LACP) support: enables the use of industry-standard network bonding features to provide fault-tolerance and load balancing of network traffic.
  • Source Load Balancing (SLB) improvements: allows up to 4 NICs to be used in an active-active bond. This improves total network throughput and increases fault tolerance in the event of hardware failures. The SLB balancing algorithm has been modified to reduce load on switches in large deployments.
  • Multi-Tenancy improvements: allows system administrators to restrict a VM to send and receive traffic on a specific MAC address and a number of IPv4 or IPv6 addresses, without relying on VLANs and switch management software. When these extensions are deployed VMs cannot impersonate any other VM, or intercept traffic intended for any other VM. This increases security in environments where VMs cannot be fully trusted. For detailed configuration see the XenServer 6.1.0 Administrator’s Guide
  • VLAN Scalability improvements: removes a previous limitation which caused VM deployment delays when large numbers of VLANs were in use. This improvement enables administrators using XenServer 6.1.0 to deploy hundreds of VLANs in a XenServer pool quickly.
  • Emergency Network Reset: provides a simple mechanism to recover and reset a host’s networking, allowing system administrators to revert XenServer hosts to a known good networking state. Refer to CTX131972 and the XenServer 6.1.0 Administrator’s Guide for detailed information.
  • IPv6 Guest Support: enables the use of IPv6 addresses within guests allowing network administrators to plan for network growth.

Guest Enhancements

  • Citrix XenServer Conversion Manager: enables batch import of VMs created with VMware products into a XenServer pool to reduce costs of converting to a XenServer environment. Refer to the XenServer Conversion Manager Guide.
  • New Installation Mechanism for XenServer Tools: XenServer Tools are now delivered as industry standard Windows Installer MSI files. This enables the use of 3rd party tools to deliver and manage the installation and upgrade of the XenServer device drivers. For more information on MSI files refer to

Enhanced Guest OS Support: Newly Supported Guests

  • Ubuntu 12.04
  • CentOS 5.7, 6.0, 6.1, 6.2
  • Red Hat Enterprise Linux 5.7, 6.1, 6.2
  • Oracle Enterprise Linux 5.7, 6.1, 6.2
  • Windows 8 (32-bit/64-bit) – experimental support
  • Windows Server 2012 – experimental support

Refer to the XenServer 6.1.0 Guest Support Guide for virtual memory and disk size limits for these new guests.

Ongoing Improvements

  • Supported number of VMs per host increased to 150.
  • XenCenter: configuration of performance graphs simplified; assignment of IP addresses simplified.
  • Performance Monitoring Enhancements Supplemental Pack: provides additional RRD metrics such as I/O throughput that can be viewed in XenCenter. Refer to CTX135033 for details
  • XenServer Tools: guests running Windows operating systems can now make use of either Microsoft .NET 3.5 or .NET 4.0 when installing XenServer Tools.
  • Simplified mechanism to adjust Control Domain (“dom0″) vCPUs. Refer to CTX134738 for details.
  • Updated Open vSwitch: v1.4.2 provides stability and performance improvements. For more information refer to
  • Integrated StorageLink (iSL) support for EMC VNX series arrays.
  • GPU Pass-through: support for up to 4 GPUs per host.
  • Interoperability extensions for 3rd Party Tools: additional asynchronous XenAPI C language bindings, Workload Balancing (WLB) extensions and general improvements. Refer to CTX135078 – XenServer 6.1.0 SDK Release Notes and CTX134685 – Workload Balancing 6.1 Release Notes.
  • Automated Server Hardware Test Kit – reduces the time spent running certification tests – refer to the Verification Test Kits & Forms for Citrix XenServer for more information.
  • Support for hypervisor monitoring (vhostmd) allows SAP software to run inside a XenServer VM. Refer to CTX134790 for configuration details.

Some of our favorites and why:

Storage VMotion will definitely be a feature that will come in handy for us on our Xenserver implementation.  The ability to now motion Xenserver VM’s on and off of a host regardless of whether they share the same storage is huge!  This will allow you to troubleshoot storage issues by moving VM’s to new storage without ever having to shut them down.  Also if you are having a storage problem with a particular storage device, you can seamlessly get all of your users to a new safer storage location without them ever having to know!

Live VDI Migration is another great feature that is going to save a lot of administrators and users headaches.  The ability to move live running VM’s from a development environment directly into production without the users ever knowing or caring will be nice, and make promoting desktops from dev to prod a breeze.

The Emergency Network Reset feature looks cool, and is something we’d like to try in the future when troubleshooting a Xenserver poolmaster is down type of issue.  We wonder if it could be used to revert network settings so that the Xenserver poolmaster would come back online with less troubleshooting?

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