6.7

Table Of Contents
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If virtual machines running on the same host communicate with each other, connect them to the same
virtual switch to avoid the cost of transferring packets over the physical network.
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Assign each physical NIC to a port group and a virtual switch.
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Use separate physical NICs to handle the different traffic streams, such as network packets
generated by virtual machines, iSCSI protocols, vMotion tasks.
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Ensure that the physical NIC capacity is large enough to handle the network traffic on that virtual
switch. If the capacity is not enough, consider using a high-bandwidth physical NIC (10Gbps) or
moving some virtual machines to a virtual switch with a lighter load or to a new virtual switch.
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If packets are being dropped at the virtual switch port, increase the virtual network driver ring buffers
where applicable.
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Verify that the reported speed and duplex settings for the physical NIC match the hardware
expectations and that the hardware is configured to run at its maximum capability. For example, verify
that NICs with 1Gbps are not reset to 100Mbps because they are connected to an older switch.
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Verify that all NICs are running in full duplex mode. Hardware connectivity issues might result in a
NIC resetting itself to a lower speed or half duplex mode.
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Use vNICs that are TCP Segmentation Offload (TSO)-capable, and verify that TCP Segmentation
Offload-Jumbo Frames are enabled where possible.
Empty Performance Charts
No graphics or data are displayed in performance charts.
Problem
When data is missing for a performance chart, the chart appears empty and you see the message No
data available.
Cause
The causes for missing data in performance charts that are described herein are based on the
assumption that the default roll-up configuration for the vCenter Server system has not changed. The
causes include but are not limited to the following scenarios:
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Metrics introduced in ESXi 5.0 are not available for hosts running earlier versions.
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Data is deleted when you remove or add objects to vCenter Server.
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Performance charts data for inventory objects that were moved to a new site by VMware vCenter Site
Recovery Manager is deleted from the old site and not copied to the new site.
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Performance charts data is deleted when you use VMware vMotion across vCenter Server instances.
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Real-time statistics are not available for disconnected hosts or powered off virtual machines.
vSphere Monitoring and Performance
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