That question prompted me to re-raise a discussion I had on Twitterand this post documents my thought process on why vMotion at the routing layer is a requirement in the modern data center. The new L3 Leaf-Spine or CLOS fabric is very common in hyperscale data centers that a lot of enterprises are seeking to emulate and in some cases, compete with. In most enterprise deployments there would likely be a pair of ToRs possibly spread across two rackswith some form of L2 host redundancy protocol running.
Or do they? This will make more sense in a minute, bear with me. This means we can treat the two separately. ESX is no different. So if you want to vMotion, the front end network must be present. Case closed.
Routed vMotion: Why?
The first thing to consider here is, by default, vMotion across subnet boundaries that is, routed will work. A lot of it is based on the assumption that routing implicitly adds latency and therefore should be avoided.
In a modern data center, this may not be the case. There is one dirty little secret people may be unaware of. What would that look like if we were forced to move to pure L2 model as has been suggested as a best practice for vMotion.
Notice that STP will shut down most of the links. Only one spine switch will be actually forwarding vMotion traffic since it is carried over a single VLAN. How is this a step forward? Generally, MLAG-like solutions have lots of caveats associated. They work in pairs only, there are Inter-Switch-Links ISLs between the pairs that must remain up and sized appropriately.
The caveat around RPQ is the process is on a customer-by-customer basis and you need to submit a design that makes sense.Another very important network that needs to be configured when multiple ESXi servers are in a cluster configuration is the ESXi vMotion network a concept we will discuss in our next post. This allows for high availability of service for VMs running in the vSphere environment and moving VMs due to hardware maintenance, updates, or other service interruptions at the physical layer.
VMs can simply be moved to another host with no interruption. We have to have a Port group on a vSwitch that is enabled for vMotion in order to successfully vMotion a VM to another host. That host, of course, would need to have a vMotion network setup as well for the move to be successful. The steps to configure the vMotion network are similar to configuring iSCSI storage networkswith a few subtle differences.
Click on the Add Networking link in the upper right hand corner. We name our first vMotion Port group. We will have one port group per vmnic that we are assigning to the vSwitch for vMotion. Also, note we are checking the box next to Use this port group for vMotion.
Add the second port group by viewing the properties of the vSwitch we created and click Add. We select that we want to use this port group for vMotion. After that, we need to assign an IP address to this VMkernel configuration.
Again, we need to go into the properties of both the vSwitch and the port groups and make the change to jumbo frames. We do the opposite for our second port group. As mentioned, the vMotion network is an important network configured on our ESXi host as it will allow multiple ESXi servers configured in a cluster to live migrate VMs between their compute resources. In creating the vMotion network, we utilized the VMkernel ports making sure we enabled jumbo frames, as well as setting our NIC teaming so that multiple network adapters would be utilized during the vMotion process.
In the next post, we will take a look at the VM network. Minimum order size for Basic is 1 socket, maximum - 4 sockets. People also read VMware Cluster. Virtual Appliance — Simplicity, Efficiency, and Scalability.It balances one vMotion session across all available VMkernel adapters. It is quite easy to configure conventional VMware vMotion. Whether it is vMotion with shared storage or shared-nothing vMotion, the configuration is the same. The configuration consists of four steps:.
However, it also not complicated. This configuration assumes you have at least two physical NICs in each host, you're using a vSphere standard switch, and you have a vMotion license. It will then apply a "cross configuration" of active-standby assignments of physical NICs to both VMkernel adapters.
After this, there are two ways to proceed: Keep everything on the same vSwitch or add new vSwitch. In this example, we will create a new vSwitch, which by default will be named vSwitch1 the first vSwitch added to a host is always vSwitch0, the second vSwitch1, etc. Next, select Create a Standard switch.
Its name will be vswitch1. Then add both NICs you want to use for the vMotion traffic and set one of them as Active and the other one as Standby. Then continue with the wizard to finish the VMkernel creation, assign a network label, and then select the vMotion service checkbox. After this, finish the wizard. Basically, you have to "cross" the active and standby assignment of the NICs for the VMkernel adapters. Now you'll need to do the same for the other hosts within your cluster.
It won't cost you much time, but for larger clusters, it might make sense to script the process via PowerCLI.
This allows you to reuse the configuration for all hosts participating in the cluster. Poll: Does your organization plan to introduce Artifical Intelligence?
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5 Awesome Tips to Troubleshoot vMotion
Unexpected downtime is nearly impossible to avoid, but you can still get prepared for a wide range of scenarios that are likely to happen occasionally. These include such downtime causes as maintenance, moves, planned power outages, and so on. To help you avoid downtime, VMware offers vSphere vMotion.
This technology allows for live migration of virtual machines VMs without interruption in their availability. This turns VMware vMotion into a solid element for creating a dynamic, automated datacenter with self-optimization capabilities. Our product offers a set of tools to let you protect your VMware-based infrastructure. These include VM Replication and Site Recovery, features that can help you handle the process of data center migration. You can create a replica, i.
You can perform live migration of your VMs from one physical host to another, without any downtime. This technology allows the VM processes to keep running throughout the migration process. Simply for reference, VMware supports cold migration mode, too, which means that migration can be performed when the VM is turned off or suspended. As live migration is performed, the VM retains its current memory content, network identity and connections, and all additional information that defines it.
On a gigabit Ethernet network, the process of migration takes less than two seconds, according to VMware documentation. To reduce the need for manual effort, you can automate and schedule the migration of your VMs.
Depending on your needs, you can schedule the migration process to run either once or multiple times.
ESXi vMotion Network Configuration
Additionally, VMware vMotion can help you find an appropriate destination host within seconds, thus eliminating the need to do this manually. Available since the vSphere 6. RTT, or round-trip time, is the length of time required for a signal or data packet to travel from a starting point to its destination and back again.
With VMware vMotion, this is about milliseconds or less. If you prefer to change the host and the datastore, both the state of the VM and the virtual disk are moved. Migration can be performed between hosts, clusters, or data centers without shared storage.
It is available in VMware vSphere 5. First and foremost, you should pay attention to the list of setup vMotion requirements. Namely, you need to properly configure network interfaces on the source and target hosts. To perform live migration of a VM from one physical host to another, VMware vMotion relies on three technologies:. First of all, the feature encapsulates the entire state of the VM.There are 8 stages to a vMotion event as illustrated in Fig.
If your environment is not adequately prepared for vMotion, you could come across issues at any stage of a vMotion task. To being with, revisit the requirements and make sure your environment is compliant. This KB article provides a complete list. In the following example Fig. If I try to migrate a VM to this host, the vMotion task immediately fails.
Figure 2 — The error returned when a VM is migrated to a host that is not set up for vMotion. Backup software will sometimes set this value to 0 disabled to ensure that backup jobs complete successfully by preventing a VM that is being backed up from vMotioning to another host.
As it sometimes happens, an unplanned network or storage outage may prevent the Backup software from rolling the setting back to its original value leaving the VM in vMotion limbo.
Figure 4 — Ensuring the migrate. VMkernel network connectivity can be another problem area resulting in timeouts or outright failed migrations. When testing network connectivity between hosts, you will want to test from a VMkernel perspective more so if your hosts are running multiple VMkernel adapters.
There are a couple of ESXi shell commands that help you do this. These are vmkping and nc. As per the next example, I am verifying that host The -I parameter is used to tell vmkping which VMkernel should be used to test network connectivity.
If a virtual machine has a mounted ISO image residing on storage not accessible by the ESXi host where you want the VM migrated to, vMotion will fail with the following remote backing error. This is another common issue and an easy one to fix. You are probably familiar with the Synchronize guest time with host VMware Tools option. What you may not know is that, independently of the option being disabled, there are instances where a VM will still synchronize its clock to that on the ESXi host.
Some instances that trigger this behavior include snapshots, restarting vmtools and, in our case, vMotioning a VM. I use the following one-liner PowerCLI to quickly retrieve the time setting on all the hosts managed by specific vCenter instances.Danish, United Kingdom Iceland Full Circle - Winter, October 2014 My brother had used Nordic Visitor the previous year to visit Iceland and he was all praises so we decided to do the same and we were not disappointed.
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VM Migration with VMware vMotion: How Does It Work?
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Table 1 shows an age frequency distribution with five categories of age ranges defined. The same frequency distribution can be depicted in a graph as shown in Figure 1. This type of graph is often referred to as a histogram or bar chart. Frequency distribution bar chart. Distributions may also be displayed using percentages.
For example, you could use percentages to describe the:Central Tendency. The central tendency of a distribution is an estimate of the "center" of a distribution of values. There are three major types of estimates of central tendency:The Mean or average is probably the most commonly used method of describing central tendency.
To compute the mean all you do is add up all the values and divide by the number of values. For example, the mean or average quiz score is determined by summing all the scores and dividing by the number of students taking the exam.
For example, consider the test score values:The Median is the score found at the exact middle of the set of values. One way to compute the median is to list all scores in numerical order, and then locate the score in the center of the sample.
Since both of these scores are 20, the median is 20. If the two middle scores had different values, you would have to interpolate to determine the median. The mode is the most frequently occurring value in the set of scores. To determine the mode, you might again order the scores as shown above, and then count each one. The most frequently occurring value is the mode. In our example, the value 15 occurs three times and is the model. In some distributions there is more than one modal value.
For instance, in a bimodal distribution there are two values that occur most frequently. Notice that for the same set of 8 scores we got three different values -- 20. If the distribution is truly normal (i. Dispersion refers to the spread of the values around the central tendency. There are two common measures of dispersion, the range and the standard deviation. The range is simply the highest value minus the lowest value. The Standard Deviation is a more accurate and detailed estimate of dispersion because an outlier can greatly exaggerate the range (as was true in this example where the single outlier value of 36 stands apart from the rest of the values.
The Standard Deviation shows the relation that set of scores has to the mean of the sample. Again lets take the set of scores:to compute the standard deviation, we first find the distance between each value and the mean.
We know from above that the mean is 20. So, the differences from the mean are:15 - 20. Next, we square each discrepancy:-5.
Here, the sum is 350. Next, we divide this sum by the number of scores minus 1. Here, the result is 350. This value is known as the variance. To get the standard deviation, we take the square root of the variance (remember that we squared the deviations earlier). This would be SQRT(50.