Jumbo frames

Jumbo frames are Ethernet frames with more than 1500 bytes of payload. Generally, jumbo frames can carry up to 9000 bytes, but variations do exist. Enabling jumbo frames in specific cases (say, in your Storage Area Network) can improve performance and network throughput. But, if you are enabling it, all devices connecting it including the source, destination and other devices in between like switches etc must support jumbo frames and should be enabled.

Enabling jumbo frames on a VMware virtual network adapter (vmxnet3) is shown below :

Jumbo Packet on vmxnet3 adapter

Steps to enable jumbo frames on a VMware vSphere 4.1 vSwitch is shown below :

List vSwitch

 By default it is 1500 MTU. Say, you want to change vSwitch1 to 9000 MTU. It can be done as follows :

Enabling jumbo frame with MTU 9000 on vSwitch1

You can verify connectivity after enabling jumbo frames by specifying packet size using ping command as given below :

Verifying jumbo frames

Creating VHD/ VHDX templates

Templates can save you lot of time, instead of building a server from scratch. Following are the steps to create a VHD/ VHDX template that can be used on Hyper-V servers.

1.Create a virtual machine (say Windows Server 2008 R2 with 80 GB hard drive)

2.Make sure you create fixed disk

3.Install OS

4.Install Windows updates

5.Install Hyper-V integration services

6.Install any applications as per your requirement

Once you are done with all the above steps, now its time to sysprep your machine. This is shown below :

sysprep

Make sure you check Generalize and shutdown options. Once the system completes sysprep operation, it will automatically shutdown. You can now take a copy of this VHD disk, rename it as you wish and save it to a location where you keep your templates. Also, make sure to make this file as read-only, so that you can avoid booting it up accidentally.

Note : You can create VHD templates for OS earlier than Windows Server 2012 and VHDX templates for Windows Server 2012 and later.

VMware virtual switches

Virtual Standard Switch (VSS)

VSS

Virtual Distributed Switch (VDS)

VDS

Reference : mylearn.vmware.com

Ports on FC Switched Fabric (FC-SW)

The diagram given below gives a brief idea about the different types of ports on a Fiber Channel Switched Fabric.

Ports on FC Switched Fabric

RAID controller

As RAID controller is responsible for the operations on RAID array drives, it is very important to have an enterprise class controller for enhanced performance, increased reliability and fault tolerance. Considering the business requirement and budget, you can choose a RAID controller. Here I will be explaining about DELL Power Edge RAID Controller (PERC). When choosing a controller, there are few critical hardware features that affect performance to keep in mind :

• Read policy
• Write policy
• Controller cache memory
• CacheCade
• Cut-through I/ O
• FastPath

PERC Series

PERC H810 - high performance RAID controller that can be connected to JBOD

PERC H710P - ideal for implementing hybrid server platforms based on SAS HDDs with high performance and enterprise class reliability

PERC H310 - entry-level RAID controller (no cache)

Reference :
Dell
Microsoft

How to calculate total IOPS supported by a disk array

IOPS stands for input/ output operations per second. 

Consider a RAID array with 4 disks in RAID 5. Each disk is 4TB 15K SAS drive. We can use the below formula for calculating maximum IOPS supported by the RAID array.

Raw IOPS = Disk Speed IOPS * Number of disks

Functional IOPS = (Raw IOPS * Write % / RAID Penalty) + (RAW IOPS * Read %)

No: of disks = 4 (4TB 15K SAS)

IOPS of a single 15K SAS disk = 175 - 210

RAID penalty = 4 (for RAID 5)

Read - Write ratio = 2:1 (say we have 66 % reads and 33 % writes)

From the above details :

Raw IOPS = 175 * 4 = 700

Functional IOPS = (700 * 0.33 / 4) + (700 * 0.66) = 519.75

Therefore, the maximum IOPS supported by this RAID array  = 520

The above calculation is entirely based on assumption that the read - write ration is 2:1. In real time scenarios it may vary depending on the type of workload. That means workload characterization is also important while calculating maximum IOPS value supported by your RAID array. It also depends on the type of RAID, as penalty will be different for different type of RAID. Disk type (SSD, SAS, SATA etc), disk RPM and number of disks also affects the total IOPS value.

From this we can conclude that, if your current IOPS usage is closer to the maximum IOPS supported, then you have to be very cautious as it may lead to I/O contentions due to heavy workloads causing high latency and performance degradation to your storage server.

Server load balancing using KEMP Load Master

This article explains the basic configuration steps for load balancing multiple web servers using KEMP load balancer. In my setup, I've two web servers (INVLABSWEB01 and INVLABSWEB02) which are load balanced using a KEMP Load Master. For the purpose of testing I've used a virtual load master appliance (VLM-5000). After the installation is complete, you have to activate the license. Once you are done with that, you can get to the home page of the load master using a web browser as shown below.

Home page

Now you have to add a virtual service. Click add new, provide a virtual address, give it a name, select a protocol and click add this virtual service.

Add new virtual service

Select a service type. Check the box to activate the service.

Expand standard options. Select the options as shown below. If you don't select Force L7 option, then the virtual service will be forced to Layer 4. Transparency can be enabled or disabled depending on the use case.

If persistence mode is enabled, the same client will subsequently connect to the same real server depending the mode selected. And there is a timeout value, that can be set which determines for how long this particular connection is remembered.

Scheduling method determines the method by which the load master selects a real server for a particular service. There are several methods like round robin, weighted round robin, least connection, resource based (adaptive) etc. Here I have selected round robin.

Basic properties and standard options

If you want to enable SSL acceleration, that can be done here.

SSL acceleration

Advanced options like enabling caching, compression, access control etc can be done here.

Advanced properties

Edge Security Pack (ESP) feature can be enabled in this option.

ESP feature

Click add new to add real servers to the virtual service (VS).

Real servers

Provide real server address, port number and click add this real server.

Add real server

Similarly, I've added two web servers (192.168.6.30 and 192.168.6.31) here.

Real servers

Click on view/ modify services to view the VS that you have just created.

Virtual services

Click on real servers to view the real servers (INVLABSWEB01 and INVLABSWEB01).

Real servers

Now, both of my web servers are load balanced. If you want to disable any of the servers from the load balancer, click disable button for the respective server.

Reference :
Kemp Technologies