How Storage VMotion Works

How Storage VMotion Works.

So how storage VMotion works?

How does SVMotion works at background and what are the process that is happening at the backend.

Storage VMotion is really a great feature which enables you to migrate your VM’s storage or Virtual disks from one datastore to another datastore without any downtime and yes now started from vSphere 5.5  using web client, you can do both VMotion and SVMotion of powered ON virtual machines simultaneously which was not possible earlier.

So when you do SVMotion, all the non-volatile files that make up a VM is been copied first to the destination datastore i.e. .VMX, swp, snapshots and log files.So how storage VMotion works?

• It starts a shadow VM on the destination datastore, as shadow VM doesn’t have virtual disks, it sits idle waiting for its virtual disks.
• VMKernel datamover starts the initial copy of migration from source datastore to destination datastore. Than Mirror driver kicks in that mirror’s I/O between source to destination.
• As I/O mirroring is in place, vSphere makes a single pass copy of virtual disks from source to destination datastore. And the changes made in between this process are been properly taken care by mirror driver by ensuring all the changes are been reflected on destination datastore also.
• Once the virtual disk copy gets completed, vSphere quickly suspends and resumes in order transferring control to the shadow VM on the datastore.
• Once it is confirmed that VM is working properly on the destination datastore, the files on the source datastore gets deleted.

What are the benefits of SVMotion?

• Using storage VMotion, you can balance utilization on datastores.
• SVMotion doesn’t require any downtime, so this becomes very helpful during storage upgradation or during any activity on storage side.
• Using SVMotion you can convert thick disk to thin disk and vice versa.
• Dynamically optimize storage I/O performance.

VMotion and Storage VMotion allow for the business’ priorities to be met without disrupting the workflow of the users.
Storage VMotion makes storage and capacity management more efficient. It is a feature of vSphere that delivers an easy, intuitive interface to allow the live migration of VM disk files across storage arrays, while causing no downtime and no interruption or heavy deterioration of the performance of the VMs. It works by relocating the VM disk files to various storage locations, enabling the business to be proactive about storage migration and to improve the performance of storage in terms of capacity management.

Like vMotion, Storage VMotion is completely integrated with vCenter Server, which allows for the easiest possible migration and monitoring.Storage VMotion works with any OS and storage hardware that is supported by ESXi. It enables administrators to take advantage of a mixture of heterogeneous file formats and data stores, without incurring any downtime.

With Storage VMotion, administrators can migrate VM disk files to alternate LUNs in order to optimize performance with no downtime. It allows administrators to increase or decrease storage allotment, without a lot of manual work. Additionally, Storage VMotion can act as a tool to tier the storage, based on the value of the data, performance requirements, and the cost of various storage solutions.

If you’re in the market for a better VMware monitoring solution, Opvizor has your answer. Snapwatcher enables VMware snapshot monitoring and reporting so that you can track invalid snapshots that can happen when migrating virtual machines. Register for Snapwatcher here, to detect and solve all kinds of bad Snapshots.

Differentiate between Virtual Machine Port Group and VMKernal Port?

Differentiate between Virtual Machine Port Group and VMKernal Port?


VMkernel ports 

VMkernel ports are used to connect the VMkernel to services that it controls. There can be many vmkernel ports however there is only one vmkernel.
Hence the vmkernel ports can be differentiated based on the service it connects the vmkernel to.
The services might be vmotion,SCSI binding,Management of the ESXi or Fault tolerant. With vSphere 5.5 there is addition of this for vSAN Network.

VM port Groups

VM port Groups on the other hand are used only to connect Virtual machines to Virtual Switches.
Primarily these can be layer 2 Switches which only need a tagging such as vLAN tagging to make sure that the Virtual machines communicate in between themselves,communicate in between the hosts,communicate to the internet etc.
With VM Port groups, you can have policies such as Security,Traffic Shaping,NIC Teaming etc.


VmKernel port group provides connectivity to hosts and handles the traffic like vMotion , management, FT traffic. We assign IP address to Virtual kernel Adapter (VMK) of VMKernel port group. Whereas all Virtual machines are connected at VM port group.

Security	Set MAC address changes, forged transmits, and promiscuous mode for the selected port groups.
Traffic Shaping	Set the average bandwidth, peak bandwidth, and burst size for inbound and outband traffic on the selected port groups.
VLAN	Configure how the selected port groups connect to physical VLANs.
Teaming and Failover	Set load balancing, failover detection, switch notification, and failover order for the selected port groups.
Resource Allocation	Set network resource pool association for the selected port groups. This option is available for vSphere distributed switch versions 5.0.0 and later only.
Monitoring	Enable or disable NetFlow on the selected port groups. This option is available for vSphere distributed switch versions 5.0.0 and later only.
Miscellaneous	Enable or disable port blocking on the selected port groups.

What is vnic, vmnic and vmk

NIC Teaming

NIC Teaming 

Load Balancing Mode

1: Address Hash
2: Hyper-V Port
3: Dynamic (Windows server 2012 R2 Only)

Teaming Mode

1: Switch Independent
2: Static Teaming
3: LACP


Windows can support up to 32 network card adaptor in the one nic team
and the load balancing more ditermines how traffice will be distributed between the network cards in the nic team
when it leaves the server. there are 3 load balancing mode that are supported. Each of the we will go in mre details

The first is adddress hash. This mode essentially uses attributes of the network traffice, like IP Address and Port
- To determies which network adaprot will be used. given the same input values the same network adaptor will always be used
if you are using virtual machines

The seconnd setting - Hyper-V sswitches port- can be  used and can control incomming and outgoing traffice.
it dies this by routing each virtual machines through tge same network adaprot each times.

The Third setting Dynamic, this is a new setting that was added in windows server 2012R2
This setting combines the features of the previous two balancing options and can change network streams from thr netowrk card to another as required.



Teaming mode :-
Some netowrk switches have support for the load balancing. if your network switches does not have that ability or you do not want to use it,
the mode, switches independent, should be used. This mode doesnot require any hardware support ont he switch.

Next two mode are static teaming and LACP. Both these modes require your network switches to support the required load balancing protocol. if youa re prepared to configure
your network switches. these options allow better utilization of your netowrk card.

I will now have a closer look at these settings, starting with the load balancing opetions followed by the teaming mode options.

Address Hash
Uses MAC/IP Address/ Poer to create hash

How VMotion Migration works?

Let's explore how VMotion migration works!

As we see our virtual machine is currently running on host 1 if we want to migrate that VM to host two using VMotion migration.

There are several requirements that we first need to meet as you can see between two host,

we need to have shared storage. the virtual machine files need to be stored in that shared storage and as a result of having shared storage the migration are actually very very quick because we need not copy any of the files,

well we actually need to be copy from the first host to the second host is the memory state of the virtual machine and that's performed across the network that we called VMotion network.

The VMotion network which we'll show you later during the segment is a private non routed, gigabit or faster network connection between the two hosts involved in the VMotion migration, now the virtual machine, on the other hand, see other networks such as

the network we have illustrated here the production network one of the requirements of the VMotion migration is that the host have the VMotion network but additionally, the

host need to have identical network configurations including identically spelled labels for the virtual machine port groups for a network such as the production network, so if the virtual machine port is called production with a capital P on the first host then the same virtual machine port group must have the exact same label on the second host it much be spelled production but with the capital P but with these pieces setup we can migrate the virtual machine from the host 1 to host 2 the way this is performed is that the host performs a bulk copy of the memory state of the virtual machine A from the first host to the second host across.

the VMotion network, while we perform that copy the challenge is that the memory location that were copying and changing, so what ends up happening if that initial bulk

copy is the VM is actually quest but the quiescing that the actual stopping of the VM is so quick that we as human don't perceive, during that period of quiescence,

the changes that occurred in the memory state are copied from the first host to the second host the VM is then unquestioned at that point VMS now on the second host,

the VM still at the same IP Address same mac address same hostname in fact from the outside world perspective nothings changed in that virtual machines expect

for one thing that virtual machine is now connected to a host which is plugged into a different physical port on the physical switch,

To address that issue we simply perform reverse ARP Broadcast and that act and the all other test we perform performed automatically for you behind the scenes the end result is you suddenly see the VM that was running on ESXi host 01 running on the second host