NetFlow is a mechanism to analyze network traffic flow and volume to determine where traffic is coming from, where it is going to, and how much traffic is being generated. NetFlow-enabled routers export traffic statistics as NetFlow records which are then collected by a NetFlow collector.

Traffic flows are defined as the combination of source and destination IP addresses, source and destination TCP or UDP ports, IP, and IP Type of Service (ToS). Network devices that support NetFlow, tracks and report information on the traffic flows, and send this information to a NetFlow collector. Using the data collected, network admins gain detailed insight into the types and amount of traffic flows across the network.

Netflow was originally developed by Cisco and has become a de-facto industry standard for analysing network traffic. VMware introduced Netflow for vDS in vSphere v5.

Note: Netflow is only supported with vDS and not standard switches.

There are various versions of NetFlow ranging from from v1 to v10.… Read More

I am currently going through VCAP 6 objective 3.2 and the very firts task in this objective is to deploy a LAG and Migrate to LACP. Although I have read about this in past and we use this in our production environment, I never got a chance to configure this in my homelab because of hardware restrictions (this is true till date 🙁

Well before jumping into LACP configuration, lets discuss a bit about few networking terms here (networking was/is always a big headache for me).

• Link Aggregation Group (LAG): The simplest definition of LAG can be defined as bonding of ethernet links in order to achieve greater throughput.
• Link Aggregation Control Protocol (LACP): This is a protocol which is defined in the 802.1AX standard, and it provides a method for automating LAG configurations. LACP-capable devices discover each other by sending LACP packets (called  LACPDUs) to the Slow_Protocols_Multicast address 01-80-c2-00-00-02. They then negotiate the forming/not forming of the LAG.

vStorage API for Array Integration (VAAI) is an API framework developed by VMware that enables certain storage tasks to be offloaded from Esxi hosts to the storage array and thus lessens the processing workload on the Esxi host. VAAI was first introduced with vSphere 4.1.

It significantly improves the performance of storage -intensive operations such as cloning storage, block zeroing , and so on and thus reduces the overhead on the ESXi host. The main goal of VAAI is to help storage vendors to provide hardware assistance to speed up VMware I/O operations.

The APIs create a separation of duty between the hypervisor and its storage devices, enabling each to focus on what it does best: virtualization-related tasks for the hypervisor and storage-related tasks for the storage arrays.

What vSphere functions can be offloaded with VAAI?

1: Copy offload: Certain operations such as deploying a new VM from template or cloning a VM etc involves copying of virtual disk files.… Read More

Storage IO control (SIOC) was first introduced in vSphere 4.1 and since then its getting better and better with every release of vSphere. This is one of those feature which easily escapes eye of a vSphere administrator while architecting/configuring environment.

As we know storage is the slowest among it counterparts like CPU and Memory and when bottleneck occurs in an environment, virtual machine can suffer serious performance.

Introduction of SDRS in vSphere 5.0 made life of vSphere administrator a bit easy as SDRS tends to balance datastores when IO imbalances starts to occur in environment. Although this sounds great, but there is one caveat in this. SDRS can’t prevent a virtual machine from monopolizing IO consumption. In other words SDRS was unable to ensure fair distribution of IO’s among virtual machine when contention occurs and as a result of this few virtual machine tends to suffer performance impacts.

So what is Storage IO Control?… Read More