In my other life as XenAgent (aka XenGirl) I am there to answer Master class attendees questions. For our last XenServer Master class in EMEA and US we had about 700 questions to answer. As you can imagine this is very stressful and we don’t have the time to answer the questions in more detail.

Masterclasses are live two hour webinars (a bit like a TV show with live presenters) where customers and partners can see product demos, learn about best practices and ask real engineers and solutions experts questions live about any aspect of the featured product. Plus all the Q&A is public so you can see and record what others ask giving you great ideas and feedback for your own deployments. It’s also a great way of getting a bit of free and instant support!

We reviewed every single one of the 700 questions we receive and I thought I am going to share 5 of them and add a little more detail to the answers.

Question:
How is it possible to run hundreds VM per host when with 2 socket and 6-core per socket CPUs there is only 24 vCPU available? So, only 24 Windows-based VM are possible in that case, right?

Answer:
No, with Citrix XenServer you can over-commit CPU resources. So you could easily assign more than vCPUs than you have physical. In theory you could assign up to 4000 vCPUs per Host, no matter how many physical CPU resources you have. In real life this obviously does not make much sense, but for certain workloads CPU over-commitment is very efficient. In other cases where CPU is critical you can pin physical CPUs to vCPU.

Question:
Can we also over-commit the RAM?

Answer:
Yes, via Dynamic Memory Control. You can set minimum and maximum memory for the VM. As long there is enough memory available the VM will receive the maximum assigned memory. If more memory is needed to start additional VMs a ballooning inside the VM expands and frees up memory.

Find out more about vCPU assignment and Dynamic Memory Control in our XenServer Administration Guide: http://support.citrix.com/article/CTX137828

Question:
Where can I download the trial version of XenServer 6.2?  Is there a free version?

Answer:
Yes, there is a full-featured free version. We don’t limit hardware resources or time you can use the free version. You can use all essential features like Storage XenMotion, integrated Disaster Recovery or Memory over-commitment. You can find the ISO here: http://xenserver.org/overview-xenserver-open-source-virtualization/download.html
Licensing is important if you run critical workloads and you want to make sure you get Citrix premium Support. More Information on how to buy XenServer: http://www.citrix.com/products/xenserver/buy.html

Question:
Is boot from SAN supported?

Answer:
Yes, we support boot from SAN. You can boot from iSCSI, FC and FCoE. You should enable multipathing during install. More information can be found in the XenServer Installation Guide: http://support.citrix.com/article/CTX137829

Question:
Are you now able to have different cpu’s on the hosts in one pool?

Answer:
We have support heterogenous pools for many years. You can add a new CPU generation to an older pool and the new features will be masked automatically. You can set manual CPU masks as well. Before you do this you should check if we support the CPU model and masking on our Hardware Compatibility List (HCL): http://hcl.xensource.com/CPUMatrix.aspx

(Note: The HCL also carries listings for all our trusted hardware partners including IBM, Dell, Broadcom, HP, Netapp, Cisco and hundreds of others)

Last but not least we had two special guest speakers:

Ramesh Kamath from NetApp. Ramesh works with us on a Plugin for XenCenter: Virtual Storage Console. If you missed the Master class, you can learn more about provisioning Storage and NetApp cloning from the overview video here: http://www.citrix.com/tv/#videos/10389

There is also some further information and links to blogs and information about NetApp and VSC on this page. You can find more products from NetApp and other Certified Citrix Parnters on the Citrix Ready Marketplace.

We also had Mayunk Jain from XenDesktop talking about the exciting new vGPU features enabling remote high-end graphics through our GRID GPU collaborations with NVIDIA.

Keep up to date with our Masterclasses or watch the ones you missed:

http://www.citrix.com/events/xenserver-master-class.html Even if you think you can’t make a MasterClass or can only make part of it, do register as they are recorded and mailed out to registrants.

See you at Master class!