A jack of all trades who simply enjoys the challenge creating things, whether from wood, metal, or lines of code in a computer. Mike has created all kinds of projects that you can follow and build yourself, from a retro arcade cabinet to plantation shutters for your home. Thanks for the info Mike! This is something I have wanted to know for a while. This is the first explanation of VMotion I can actually understand. Thanks for writing this Mike! Super cool! Some really smart people figured this out.
Way smarter than me! How VMotion Works! About The Author. Related Posts. Jason Vanucci on April 3, at pm. Both vSphere features are no longer usable when the source or the destination is offline. VMware vMotion and Storage vMotion effectively protect against downtime because they can bridge maintenance windows on the hosts and datastores without any interruption of service.
However, contrary to popular speculation, they are not tools designed to increase high availability. Readers have certainly already heard of VMware vMotion, the live migration function within VMware vSphere , so this introduction will be brief. With vSphere 5. This procedure was previously only possible as a cold migration process with offline VMs.
However not every virtual machine is well suited for vMotion. This point will be further discussed later in the chapter. Upon delving a bit deeper into vMotion one must admit that the functionality is both simple and ingenious.
It ensures system reliability during a traditionally problematic time — maintenance of the host. Additionally it is easy to notice in vMotion how important it really is to separate the hardware from both the operating system and the applications. As you can see vMotion is concerned mostly with the transfer of the main memory contents from one ESX server to another, with a final notification telling the physical network about the new interface over which the VM is reachable sent once the process is finished.
The guest system of course does not notice anything. As you can see in Table 1. The vMotion module starts the actual vMotion process and controls the data transfer.
Therefore an active vMotion process must always be allowed to run to completion even in the case that vCenter crashes.
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. The migration details can be set up via the Migrate Virtual Machine wizard. Depending on your needs, you can schedule the migration process to run either once or multiple times.
Additionally, VMware vMotion can help you find an appropriate destination host within seconds, thus eliminating the need to do this manually.
If you are running a large infrastructure that spans across multiple locations or countries, VMware offers functionality for migrating VMs over large distances. 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.
The RTT has been increased by almost 10 times, which means you can easily perform migration of live workloads between datacenters located on different continents. If you prefer to change the host and the datastore, both the state of the VM and the virtual disk are moved.
VMware Storage vMotion was introduced and allows moving running virtual machines between storage devices while they are running, with no downtime to the virtual machine, disruption to end users, or any loss of data.
In this post, we will look at Storage vMotion — A Brief Walkthrough and see how the technology works, what it is used for, and how to automate it. As defined by VMware, Storage vMotion allows you to migrate a virtual machine and its disk files from one datastore to another while the virtual machine is running. You can choose to place the virtual machine and all its disks in a single location, or you can select separate locations for the virtual machine configuration file and each virtual disk.
The execution host is not changed during the Storage vMotion progress. Before taking advantages of Storage vMotion, it is important to make note of the requirements and limitations of the technology. What are the requirements and limitations of Storage vMotion? VMware vSphere hosts have an overall maximum cost per host of 8. You can combine or mix and match operations to equal this cost for simultaneous operations that can happen at the same time with ESXi.
The process that takes place with a Storage vMotion is well documented from VMware. Storage has traditionally been one of the trickiest areas of infrastructure to maintain. Any maintenance tasks or reconfiguration has traditionally resulted in tremendous down time.
Back in the old days of server storage where physical LUNs hosted files and other business-critical services, it was a major event to have to move resources around. The beautiful thing about virtualized environments is the abstraction provided from the physical hardware and infrastructure to workloads. This leads to tremendous advantages over strictly physical environments, including traditional physical storage.
However, what are the day-to-day use cases that would lead to leveraging Storage vMotion in your environment. We will look at the following:. The migration benefits and capabilities offered by Storage vMotion allows businesses to have much more flexibility in storage environments as opposed to traditional storage provisioning. Virtual Machine workloads can effectively be moved in a non-disruptive manner between storage environments.
With traditional storage environments such as adding new storage disks and arrays, storage reconfiguration and provisioning is very disruptive to the service of production workloads that may be utilizing storage.
Without the ability to effectively migrate your production workloads from one storage subsystem to another, the service interruptions can be significant. Without technologies like Storage vMotion, the disruption even to virtualized workloads can be equally significant. If a maintenance operation to underlying physical storage is scheduled, you would have to schedule the move of virtual machine evacuation from the underlying storage where maintenance operations will be performed.
This would include powering off the virtual machine, moving the virtual storage from storage A to storage B, then powering the VM back on. As you can imagine, if you have tens maybe hundreds of VMs, this process would be very disruptive and time consuming.
Now, think about the same process where you have Storage vMotion at play. With Storage vMotion, the same scheduled storage maintenance can be performed without any downtime to production workloads.
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