I recently got a new corporate laptop with Windows 8 installed, as I needed to do some lab work I installed VMware Workstation 9 and installed a copy of nested VMware vSphere 5.1 as VMware Workstation delivers this natively. Read more
Tag Archive for Hyper-V
Hypervisors and the features discussions, will this become obsolete?
With the upcoming release of Hyper-V 3.0 we see a lot of movement from both VMware and Microsoft on marketing level so all features are promoted, recently this type of marketing became a bit more ugly as VMware launched a ‘Get the facts‘ and older blogs from Microsoft on ‘Windows Server 8: Hyper-V 3.0 Evens the Odds with vSphere‘. Dan Brinkmann posted a very useful overview (from a Microsoft perspective) on his blog.
Citrix: XenDesktop 5 on Hyper-V
I’m building a demo site with Xendesktop 5 on Hyper-V (including MCS and no PVS, because it’s just a demo). While the installation went without real problems the configuration had some minor issues. I used the CTX127578 article as a reference.
1) No storage available while configuring Machine Creation
When I tried to configure Machine Creation in XenDesktop 5 I discovered that I didn’t have any storage available on my Hyper-V servers according to XenDesktop. One of my collegues configured the Hyper-V servers and used CSV so I knew there was shared storage available.
So in my case nothing showed up under Storage. I went looking for the answer and it was relatively easy because you have to create a share at the Cluster Storage (c:\ClusterStorage) directory on one of your HyperV Servers. You can do it on multiple HyperV servers in your cluster but one should be enough.
As stated here by Jamal Ahmed
Select “ClusterStorage” folder => Right Click => Select Properties => Clcik on Sharing Tab => Click on “Advanced Sharing” => Enable “Share this folder” (it is at the top of the screen).
After this change the shared storage was displayed in the wizard and I was able to continue with the wizard.
2) No resources available while creating Virtual Machines
When I tried to create some VM’s using the Machine Create option from the Desktop Studio I got an error message “Host does not have sufficient resources”:
When I looked up this error message I found the following post on the Citrix forum:
The first thing to check is the properties of the cluster in the SCVMM console and ensure that the “Cluster reserve state” is OK. If this is showing overcommitted then XenDesktop will not create more virtual machines in the cluster
So what is the Cluster Reserve State:
Depending on your needs, you can configure a cluster reserve for each host cluster that specifies the number of node failures a cluster must be able to sustain while still supporting all virtual machines deployed on the host cluster. If the cluster cannot withstand the specified number of node failures and still keep all of the virtual machines running, the cluster is placed in an Over-Committed state, and the clustered hosts receive a zero rating during virtual machine placement. The administrator can, during a manual placement, override the rating and place an HAVM on an over-committed cluster.
For example, if you specify a node failure reserve of 2 for an 8-node cluster, the rule is applied in the following ways:
- If all 8 nodes of the cluster are functioning, the host cluster is marked Over-committed if any combination of 6 nodes (8-2) in the cluster lacks the capacity to accommodate existing virtual machines.
- If only 5 nodes in the cluster are functioning, the cluster is marked Overcommitted if any combination of 3 (5-2) nodes in the cluster lacks the capacity to accommodate existing virtual machines.
VMM’s cluster refresher updates the host cluster’s Over-committed status after each of the following events:
- A change in the cluster reserve value
- The failure or removal of nodes from the host cluster
- The addition of nodes to the host cluster
- The discovery of new virtual machines on nodes in the host cluster
The cluster reserve is set on the General tab of the host cluster properties.
View the status of the cluster, and adjust the cluster reserve.
- In the Cluster reserve field, specify the maximum number of node failures the cluster must be able to sustain but still keep all existing virtual machines running. If the rule is violated, the host cluster is marked Overcommitted
After setting the proper values and modifying the Cluster Reserve nodes I was able to create a couple of VM’s and use them in XenDesktop.
Citrix: Virtualization Best Practices for XenApp
Daniel Feller posted another great blogpost on the Citrix Blogs
One of the first questions when virtualizing XenApp is how many VMs to put on a server. Well, that was discussed in the Virtualize XenApp blog. Once you figure out how you plan to carve up the physical server, one of the next common questions is deciding which features of the hypervisor to enable/disable. For example, if I use XenServer, should I use the “Optimize for XenApp” setting? What about vSphere’s Transparent Page Sharing feature? And the big whopper, how should I allocate memory to my virtualized XenApp servers? Is it safe to use dynamic memory or am I safer to stick with fixed memory?
The following table is what Citrix Consulting has seen and recommends. By the way, if you want the entire discussion on virtualizing XenApp, then go to the XenDesktop Design Handbook and look in the Planning Guide section for XenApp Virtualization Best Practices.
| Decision | Justification | Hypervisor |
|
Overcommit CPU:
No
|
It is advisable not to allocate more vCPU than there are physical cores within the given hardware. Experience has shown that greater levels of scalability are achieved by not overcommitting CPU. |
Hyper-V
XenServer
vSphere
|
|
Utilize Hyper-threading:
Yes
|
Newer processors have the ability to do hyper-threading, where each core is two logical cores. Utilizing hyper-threading in a XenApp environment has been shown to improve user density. |
Hyper-V
XenServer
vSphere
|
| Disable ASLR: No | As many organizations try to protect their XenApp servers from viruses, malware and other OS exploits, it is advisable to keep Address Space Layout Randomization enabled, which is the default setting. The functionality is included with Windows 2008, Windows 2008 R2, Windows Vista and Windows 7. |
Hyper-V
XenServer
vSphere
|
|
Enable Transparent Page Sharing:
Depends on OS
|
Enabling or disabling Transparent Page Sharing has not been shown to either help or hurt performance on newer systems (Windows 2008, Windows 2008 R2, Windows Vista and Windows 7). However, older systems (Windows 2003 and Windows XP) have benefited, mostly because the page sizes are smaller (4K), thus making it easier to share pages of memory. | vSphere |
|
Optimize for XenApp:
N/A
|
On systems utilizing pre-Nehalem processors, the XenServer setting “Optimize for XenApp” provided increased scalability. Since the release of the Nehalem processors, much of the functionality has been placed on the hardware so this particular XenServer setting can be ignored. | XenServer |
| Disk Alignment: Yes | As a host server will be running multiple instances of a server operating system, it is even more important to optimize the disk subsystem to improve performance and scalability as opposed to a system running a single operating system. Windows 2003 is misaligned with default installations. This should be corrected installation to help reduce storage impact. |
XenServer
Hyper-V
vSphere
|
|
Memory Allocation:
Fixed
|
As users are dynamically load balanced across XenApp servers, memory usage between different virtual machines should be similar, helping negate the need for dynamic memory allocation techniques. Also, if VM migration strategies are used, this could cause memory overcommit resulting in aggressive paging and poor performance across all XenApp virtual machines. It is advisable to set fixed values for memory reservations for XenApp virtual machines. | XenServer Hyper-V vSphere
|
| Host Swapping: No | In most environments, all XenApp servers are actively hosting users at the same time. Swapping out memory from one XenApp host will degrade performance for all virtual machines as the memory keeps getting transferred to/from disk. | vSphere |
