vFrank

Transparent Page Sharing is the technology in VMware that scans and reclaims pages in memory. For instance if two virtual machines have the same content in memory VMware will share them to give more memory back to other virtual machines. You could compare it to some deduplication storage techniques.

This is a great technique and actually works really well with close to no overhead.  This is enabled pr. default and will easily reclaim 20-30% memory on older processor systems.

TPS only scans and reclaims 4KB pages. With the latest hardware geneations from Intel and AMD the MMU has moved to hardware. When using this feature VMware will use Large Pages

of 2MB instead of the 4KB prior. TPS does not scan the Large Pages because they are so big they would probably not find any two that matches.

What this means is that you wont see the same amount of memory being reclaimed and freed up for other virtual machines. When moving to the latest hardware generation expect to use 20-30% more memory pr. Physical ESX host.

VMware KB

If you are already a VCP and looking for more the VMware Advanced Certified Professionel certifications have arrived. It will be possible to take two VCAP certifications. VCAP – Datacenter Administrator and VCAP – Design Administrator. The first one should arrive July 12th.

The blueprints for the exam is available here: http://mylearn.vmware.com/register.cfm?course=70779

The test consists of 40 live labs and 9 questions.

I am hoping to get this test done in July.

Finally they are here. We have waited for so long. With the release of ESX 4 update 2 NFS statistics is now available for NFS datastores.

This should make storage troubleshooting a lot easier and accessible. Well done VMware.

Enhancement of the esxtop/resxtop utility— vSphere 4.0 Update 2 includes an enhancement of the performance monitoring utilities, esxtop and resxtop. The esxtop/resxtop utilities now provide visibility into the performance of NFS datastores in that they display the following statistics for NFS datastores: Reads/s, writes/s, MBreads/s, MBwrtn/s, cmds/s, GAVG/s(guest latency).

Just checked my inbox and there was a a nice mail from VMware. I have been designated as vExpert 2010! Thanks for the nominations guys.

Resource pools is a way to logically abstract CPU and Memory resources to groups of virtual machines. Resource pools is a very complex thing and you need to know what the different options “Reservations”, “Limits” and “Shares” does and how they work.

A very common but (sometimes) misunderstood implementation of Resource Pools is the HIGH, NORMAL, LOW approach. You basicly create three resource pools. High (with HIGH cpu and Memory shares), Normal (With Normal cpu and memory) and Low (With Low cpu and memory shares). Then you drag and drop your virtual machines into the resource pool you want.

The CPU sheduler in VMKERNEL then uses a proportional share algorithm to give CPU and Memory to the VM’s.

This is a fine approach in SOME cases, that is if you know what this actually means. A lot of my customers are doing this to prioritize their virtual machines. They then expect a virtual machine in the HIGH resource pool to always get more CPU time than a virtual machine in the LOW resource pool. This is not the case.

Lets look at the shares to see what this implementation actually means. The shares value for High is 4, Normal 2 and Low 1:

Total shares = 7 (100%)
High 4 (57%)
Normal 2 (28%)
Low 1 (14%)

What this implementation actually does is carve up your ESX host resources or Cluster resources into three resource pools. In case of contention your high virtual machines will get 57% of the total resource, Normal 28% and Low 14%. If this is what you want great!

But if you wanted to make sure a High VM always gets more access to a CPU than a machine in Low this is not the case. Lets for instance look at the following case. You drop 2 virtual machines into the High resource pool, 4 machines into the Normal and 1 machine into the low and start a cpubusy script in each VM. This means that the 2 in high will share the 57% of the total resources. The 4 in Normal will share the 28% and the ONE in low will have the 14% to its own use. Lets look at the following screenshot from ESXTOP with this excact setup:

Look at the %USED coloumn. The fbp_low1 virtual machine gets 65% CPU usage, the 4 machines in Normal gets approx. 33% and the two in High gets 96%.

Conclusion:

If you use this resource pool design to carve up you enviroment with minumum resources to your pools you got it right. But if you use this approach to always make sure a VM in HIGH always gets more CPU than a VM in Normal or Low this is NOT the case.

I get a lot of questions regarding whether to use ESX or ESXi. I have been working with VMware for a long time and have loved using ESX because of the easy accessible service console. My recommendations so far have been:

New to VMware: Use ESXi – you have never used the service console and won’t miss it.

Already using VMware: Use ESX if you have special scripts and 3rd party applications that relies on the SC.

Last week I delivered my first vSphere Design Workshop. Some of the course content was very direct regarding this matter. Actually this is the first place I have seen it in writing from VMware.

§First choice is ESXi Embedded, whenever possible.

•ESXi is the future.

­VMware has announced its intention to eventually replace ESX with ESXi.

§Design the management infrastructure to support VMware® ESXi, even if deploying VMware ESX™.

•Limit the use of service console–based command-line management and monitoring agents.

•Develop ESXi management techniques now because ESX will eventually be phased out.

1) Open a command window with elevated privileges (Start -> Right-click
“Command Prompt”, select “Run as Administrator”)

2) In the command window, execute the following commands:

SET DEVMGR_SHOW_NONPRESENT_DEVICES=1

START DEVMGMT.MSC

The second command starts the Device Manager. It MUST be started from the
elevated-privilege command window for this procedure to work.

3) In Device Manager, click the VIEW menu item and select “Show hidden
devices”.

Just going through the vSphere Design Workshop before delivering it tomorrow. Two Best Practises I want to bring out to everyone:

Choice of hypervisor: ESX or ESXi ?

ESXi

Choise of Physical or Virtual vCenter server?

Virtual

One of my favorite bloggers and performance guru Scott Drummonds has posted some info on Hyper-Threading and vSphere.

On earlier Intel Processors it was best practise to disable Hyper-Threading. But with the I7/Nehalem/x5xx processors from Intel you should be adviced to ENABLE it. In many use cases it can give a 10-30% performance boost. Check out Scotts blog for all the goodies.

Just stumbled over this great article by Jason Boche. There have been a lot of issues regarding the svga driver and Windows 2008 R2. Basicly before 4.0 update 1 you had to disable the vmware tools svga driver and use the generic windows. From Update 1 you can use the driver provided by vmware tools. Unfortunately it is not automatically installed so you must go to device manager and upgrade driver. The driver path is:

C:\Program Files\Common Files\VMware\Drivers\wddm_video

After driver installation your mouse will be smooth when using the Remote Console from your vSphere client.