Enabling Jumbo Frames for iSCSI Storage Arrays

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Enabling Jumbo Frames for use with an iSCSI storage array requires three steps as listed below:

A. Configure the MTU on the VMKernel port: To enable jumbo frames for iSCSI, we need to increase the Maximum Transmission Unit (MTU) size of the VMKernel port on the ESXi host. By default, the MTU size is set to 1500 bytes, which is the standard Ethernet frame size. To configure the MTU size of the VMKernel port, follow these steps:

1. Log in to the vSphere Web Client or vSphere Client and select the ESXi host.
2. Go to the Configure tab and click on Networking.
3. Select the VMKernel adapter that is used for iSCSI and click Edit.
4. Set the MTU size to a value that is supported by your iSCSI storage array. Most storage arrays support MTU sizes between 9000 and 9216 bytes.

B. Configure the MTU on the virtual switch: After setting the MTU on the VMKernel port, we need to configure the MTU on the virtual switch to match the VMKernel port. To do this, follow these steps:

1. In the same Networking window, select the virtual switch that is connected to the VMKernel adapter and click Edit.
2. Set the MTU size to match the value configured on the VMKernel port.

C. Configure the MTU on the physical switch: To enable jumbo frames for iSCSI, we need to make sure that the physical switch connected to the ESXi host and the iSCSI storage array also supports jumbo frames. To configure the MTU on the physical switch, follow these steps:

1. Log in to the management interface of the physical switch and navigate to the port that is connected to the ESXi host.
2. Set the MTU size to match the value configured on the virtual switch.

In summary, to enable Jumbo Frames for use with an iSCSI storage array, we need to configure the MTU on the VMKernel port, virtual switch, and the physical switch. Note that the configuration may vary depending on the hardware and network topology in use.