Wednesday, February 5, 2014

Vmware Notes (I)

Recently, I have been reading a little bit about Vmware, usually, I am Hyper-V guy, but probably in a short time I am going to work with Vmware.
I have been doing a little bit of research about Vmware and here are some notes that I have taken/pasted about this topic.
This article, doesn't cover all topics regarding Vmware, probably I will write a second article where I will extend it.
I hope these notes will be useful to you.
Useful tips
First step restart services if it is possible:
#service mgmt-vmware restart
#Management Agents
#service  vmware-vpxa restart
Verify network connectivity between sites , DNS resolution, Ping/vmkping,arping,gateway.
Review advanced settings , migration.enabled must be set to 1.

Cloning and deploying

Useful tips
Context menu over the virtual machine allow you to do a clone of the virtual machine in different host and storage.
Customization in rules and profiles allow to do a modifications over the cloned machine, such as name, timezone,network settings, etc.
Right click over VM and click over template, it change the type of vm to template, you can´t start a VM template, you have to apply template process over a reference VM.
Three types of deployment, not customized, customized via wizard, customized via sysprep file.



General troubleshooting



Resources (Memory swap and ballooning)

%RDY  - high track of this value - (Related with OVH CPU problems one year AGO)
VMWAIT is mostly an indicator of a host under I/O pressure.
The Percentage of system time that was spent on behalf of some other Resource Pool/World while Resource Pool/World was scheduled.

CPU metrics
If higher than 10% for a long time, add more CPU cores tho your vSphere host
This only occurs in a VM with more than 1 vCPU. Add more pCPU to the host or decrease the amount of vCPUs in the VM
If higher than 0% the vCPU is throttled because of CPU limits
If higher than 20% the VM is like a high I/O VM. Check guest OS for problems
The pCPU is not running at its rated clock frequency. Probably due Power saving.

If your using VMware vSphere, there are many different ways to monitor for memory problems.  The Virtual Center database is the first place you should start.  Check your physical host memory conditions, then work your way down the stack to the virtual machine(s) that might be indicating a problem.  Take a look at esxtop, check some of the key metrics that we discussed above.
Look for the outliers in your environment.  If something doesn’t look right, that’s probably the case.  Scratch away at the surface and see if something pops up.  Use all possible tools available to you like PowerCLI.  Approaching problems from a different perspective will sometimes bring light to a situation you weren’t aware of.  If all else fails, engage VMware support and open a service request.  Support contracts exist for a reason and I have opened many SR’s that were new technical problems that have never been discovered by VMware support.

In VMware, storage latency for guest VMs is a combination of kernel latency (the time the I/O request needs to make it through the hypervisor), and the latency from the storage device and hardware associated with the storage device.  The relationship is:
Where GAVG is the guest average latency, KAVG is the kernel average latency, and DAVG is the device average latency.  The Yellow Bricks web site discusses using the esxtop command in the ESX shell to observe these values, and provides a suggested threshold for DAVG of 25 ms.  However, VMware recommends keeping DAVG consistently between 10-15 ms in order to meet most SLA requirements.
The KAVG threshold is generally recommended to be <= 2ms, and if the value is significantly higher than this, the problem could be due to queuing in the kernel (QAVG) – which should be =  0 according to VMware’s vSphere 5 documentation.

VPXD-It is Vcenter Server Service. If this service is stopped then we will not able to connect to Vcenter Server via Vsphere client.
VPXA-It is the agent of Vcenter server. also known as mini vcenter server which is installed on the each esx server which is managed by Vcenter server. What are the management action we are performing on top of the vcenter server. (Like:- Increasing/Decreasing RAM & HDD, Making any type of changes in cluster,
doing vmotion. This agent collects all information from the vcenter server and pass this information to the kernal of the esx server.
HOSTD- This is the agent of ESX server, here VPXA pass the information to the HOSTD and hostd pass the information to ESX

ping service console network connectivity command

vmkping VMkernel network connectivity command

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