My apologies for a potentially silly question. In my work environment we run multiple VM's using Hyper-V. I poll these VM's SNMP using Observium mainly for graphing purposes. The Host machine is an Intel Xeon E5-2407 # 2.4GHZ x2, my question is if I look at the graphs of the host machine's CPU, it peaks at around 8% CPU utilization. If I check the other VM's they look like:
VM1 - 4 vcore's - 50% / VM2 - 4 vcore's - 45% / VM3 - 2 vcore's - 50% / VM4 - 4 vcore's - 3%
Could it really be possible that the host machine is barely doing any processing even though the actual virtual machines are hitting 50% of their processing power? Do you think that the Hyper-V polling is incorrect? Anyone has any experience with this before?
I would appreciate any feedback, thank you!
Due to nature of virtualization, monitoring CPU utilization inside the VM isn't acurate. Short version: processor scheduling is maintained by hypervisor, so VM doesn't really know how much it consumes.
MSDN article describes this in detail, if you want a solid overview.
Related
I am running Apache Guacamole on a Google Cloud Compute Engine f1-micro with CentOS 7 because it is free.
Guacamole runs fine for some time (an hour or so) then unexpectantly crashes. I get the ERR_CONNECTION_REFUSED error in Chrome and when running htop I can see that all of the tomcat processes have stopped. To get it running again I just have to restart tomcat.
I have a message saying "Instance "guac" is overutilized. Consider switching to the machine type: g1-small (1 vCPU, 1.7 GB memory)" in the compute engine console.
I have tried limiting the memory allocation to tomcat, but that didn't seem to work.
Any suggestions?
I think the reason for the ERR_CONNECTION_REFUSED is likely due to the VM instance falling short on resources and in order to keep the OS up, process manager shuts down some processes. SSH is one of those processes, and once you reboot the vm, resource will resume operation in full.
As per the "over-utilization" notification recommending g1-small (1 vCPU, 1.7 GB memory)", please note that, f1-micro is a shared-core micro machine type with 0.2 vCPU, 0.60 GB of memory, backed by a shared physical core and is only ideal for running smaller non-resource intensive applications..
Depending on your Tomcat configuration, also note that:
Connecting to a database is an intensive process.
Creating a Tomcat with Google Marketplace, the default VM setting is "VM instance: 1 vCPU + 3.75 GB memory (n1-standard-1) so upgrading to machine type: g1-small (1 vCPU, 1.7 GB memory) so should ideal in your case.
Why was g1 small machine type recommended. Please note that Compute Engine uses the same CPU utilization numbers reported on the Compute Engine dashboard to determine what recommendations to make. These numbers are based on the average utilization of your instances over 60-seconds intervals, so they do not capture short CPU usage spikes.
So, applications with short usage spikes might need to run on a larger machine type than the one recommended by Google, to accommodate these spikes"
In summary my suggestion would be to upgrade as recommended. Also note that, the rightsizing gives warnings when VM is underutilized or overutilized and in this case, it is recommending to increase your VM size due to overutilization and keep in mind that this is only a recommendation based on the available data.
Is there any possibility of running Orion ContextBroker on Raspberry Pi with Raspbian OS?
The requirements recommended in the Orion documentation are:
Although we haven't done yet a precise profiling on Orion Context
Broker, tests done in our development and testing environment show
that a host with 2 CPU cores and 4 GB RAM is fine to run the
ContextBroker and MongoDB server. In fact, this is a rather
conservative estimation, Orion Context Broker could run fine also in
systems with a lower resources profile. The critical resource here is
RAM memory, as MongoDB performance is related to the amount of
available RAM to map database files into memory.
Besides the board constrained resources, you will have to search about the equivalent required libraries for RaspbianOS.
There is a discussion about it here:
https://github.com/telefonicaid/fiware-orion/issues/15
Am starting to learn openstack. As per my understanding (after reading all the docs) is that the compute nodes run a host OS (ubuntu or other linux) and on top of that you have your hypervisor (like KVM) and then the VMs run on top of it i.e HW -> OS -> Hypervisor -> VMs . This is similar to having a VM running on Virtualbox which runs on a host operating system i.e HW-> Host OS ->VBox -> VMs.Please correct me if my understanding is incorrect.
Assuming my first understanding is correct, How will the performance of the VMs on the this architecture be compared to running the VMs directly on hypervisor i.e HW-> Hypervisor (KVM)->VMs ?
Comparing this with VMWare openstack architecture where Nova speaking to VMWare vCenter and then vCenter manages the ESXi nodes (vCenter and ESXi are on different nodes). This way my VMs are directly running on top of hypervisor connected to HW (HW->ESXi->VMs).And all the overlay networking is handled by NSX. This looks much more performant compared to the other architecture. Am i missing something here ?
Thanks in advance.
~exp8
Since kvm runs on linux kernel, and runs instructions directly on the cpu, it is the hypervisor (HW -> HyperVisor -> VM). On the VMware side, there is a tiny proprietary tuned version of linux as hypervisor.
To find out which one is more efficient, you should do benchmarking. But if you think Vmware's linux consumes less resources (less process, memory, cpu), it may be better.
We have recently purchased the new server having 16 GB of RAM. We have created 5 virtual machine. Out of these 5 virtual machines three are windows VM and the remaining two are Linux VM.
We have been contsantly facing the poor response of the virtual machines and the network / infra team is not able to tell us the root cause of the problem and providing the solution.
Can you please let me know what could be the possible cause of the slow down.
Additionally, we want to have the audits conducted to see if the infrastructure / network for our company has been setup correctly. Can you please let me know what are the typical audit parameters we evalluate for the best performance of Network and SYstems resources.
Thanks for the help.
Memory (RAM) is being distributed among so many VMs, each VM has very less RAM available for its own use.
On a multicore machine, does the JVisualVM CPU usage graph show total machine CPU capacity or something else?
As an example, on a machine with 16 cores, if I see CPU usage in JVisualVM going up to 50 percent, does that mean the equivalent of 8 cores fully in use?
I just tested with VisualVM 1.3.2 and the CPU display is calibrated so that 100% is 100% of all cores.
I tested by creating a simple application that entered a tight while loop upon launch. I verified using Activity Monitor that Java was using 100% of one core. In VisualVM it showed approximately 12% CPU usage.