5

I saw lots of article,but didn't answer my question.

My server use VMware vSphere Hypervisor. There are 20 virtual machines in my server.

VM operating system : centos7

I already change my vSwitch and VM Network bandwidth to 1000000000 KB/s

so other vm would not affect my dtr (data transfer rate).

Now my dtr is 170 ~ 200 MB/s

How do i increase my dtr to 500 MB/s,so that i could transfer a 20 GB file from A vm to B vm faster.

VM A : nc -l 20000 > /dev/null

VM B : time dd if=/dev/zero bs=100M count=200 | nc <VM A> 20000

200+0 records in
200+0 records out
20971520000 bytes (21 GB) copied, 122.466 s, 171 MB/s

real    2m2.479s
user    0m2.148s
sys     3m10.841s

Thanks in advanced.

  • What is your disk transfer rate? Is it even faster than that? What are your disks? – Halfgaar Nov 7 '18 at 8:09
  • My disk transfer rate is 50 MB/s,but here i talk about Network transfer rate. – kevin su Nov 7 '18 at 8:12
  • Yes, but where does the file go? – Halfgaar Nov 7 '18 at 8:15
  • 1
    So how long does the copy take now? The file comes from disk and goes to disk, so you may be trying to solve the wrong problem. – Halfgaar Nov 7 '18 at 8:21
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    You can't. You have to change the adapter to VMXNET3, and in order for this to work you have to install VMware tools. Only VMXNET adapters give 10gbit speed for esx-internal traffic. – Tobias Nov 7 '18 at 8:46
9

Since it seems to be a solution, I am adding it as answer:

When creating a VM, the default network adapter is an emulated Intel E1000E. This adapter works in most operating systems without additional drivers, but is unstable and can only use 1Gbit.

To use full 10 Gbit traffic between vms on the same host (or through 10Gbit connections to your network) you have to add a vmxnet3 adapter. You cannot change the adapter type, you have to create a new one. Even if you use the powercli to change the adapter type, it will create a new adapter, so network settings and mac address will be reset.

In order for the vmxnet3 adapter to work, on some systems (especially Windows) you have to install VMware Tools, since the drivers for this adapter are included there (Thanks to Gerald and John for the additional information).

  • The drivers are not included in Windows. They are in the Linux kernel. – Gerald Schneider Nov 7 '18 at 10:08
  • @GeraldSchneider I am not realy sure what you mean. Do you think that something about my answer is not correct? – Tobias Nov 7 '18 at 10:13
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    Your statement that it is necessary to install the VMware tools is only correct for VMs running Windows, not for VMs running Linux. – Gerald Schneider Nov 7 '18 at 10:39
  • As far as i know and as far as I have read, most Linux distributions do not support vmxnet3 adapters without the tools - is that not correct? – Tobias Nov 7 '18 at 10:42
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    vmxnet3 was merged in Linux 2.6.32. git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/… There are reasons to install VMware tools, but a Linux network driver is not one of them. – John Mahowald Nov 7 '18 at 13:02
-2

Use the virtio interface instead. It's a para-virtualized device exposed to the host by the guess' kernel. There's no network adapter in the guess anymore, reducing the driver overhead significantly. Its support has been included in all Linux kernels ⩾ 2.6.25

So-called "full virtualization" is a nice feature because it allows you to run any operating system virtualized. However, it's slow because the hypervisor has to emulate actual physical devices such as RTL8139 network cards . This emulation is both complicated and inefficient.

Virtio is a virtualization standard for network and disk device drivers where just the guest's device driver "knows" it is running in a virtual environment, and cooperates with the hypervisor. This enables guests to get high performance network and disk operations, and gives most of the performance benefits of paravirtualization.

https://wiki.libvirt.org/page/Virtio

See also the tag and

I don't know the exact name for virtio in VMware but looks like it's VMXNET 3

VMXNET 3: The VMXNET 3 adapter is the next generation of a paravirtualized NIC designed for performance, and is not related to VMXNET or VMXNET 2. It offers all the features available in VMXNET 2, and adds several new features like multiqueue support (also known as Receive Side Scaling in Windows), IPv6 offloads, and MSI/MSI-X interrupt delivery. For information about the performance of VMXNET 3, see Performance Evaluation of VMXNET3 Virtual Network Device.

Choosing a network adapter for your virtual machine (1001805)

You can read VMware's Performance Evaluation of VMXNET3 Virtual Network Device


For more information read Virtualbox's recommendations on improving performance, many of which apply to VMware as well

6.11. Improving network performance

VirtualBox provides a variety of virtual network adapters that can be "attached" to the host's network in a number of ways. Depending on which types of adapters and attachments are used the network performance will be different. Performance-wise the virtio network adapter is preferable over Intel PRO/1000 emulated adapters, which are preferred over PCNet family of adapters. Both virtio and Intel PRO/1000 adapters enjoy the benefit of segmentation and checksum offloading. Segmentation offloading is essential for high performance as it allows for less context switches, dramatically increasing the sizes of packets that cross VM/host boundary.

Three attachment types: internal, bridged and host-only, have nearly identical performance, the internal type being a little bit faster and using less CPU cycles as the packets never reach the host's network stack. The NAT attachment is the slowest (and safest) of all attachment types as it provides network address translation. The generic driver attachment is special and cannot be considered as an alternative to other attachment types.

The number of CPUs assigned to VM does not improve network performance and in some cases may hurt it due to increased concurrency in the guest.

Here is the short summary of things to check in order to improve network performance:

  1. Whenever possible use virtio network adapter, otherwise use one of Intel PRO/1000 adapters;
  2. Use bridged attachment instead of NAT;
  3. Make sure segmentation offloading is enabled in the guest OS. Usually it will be enabled by default. You can check and modify offloading settings using ethtool command in Linux guests.
  4. Perform a full, detailed analysis of network traffic on the VM's network adaptor using a 3rd party tool such as Wireshark. To do this, a promiscuous mode policy needs to be used on the VM's network adaptor. Use of this mode is only possible on networks: NAT Network, Bridged Adapter, Internal Network and Host-only Adapter.

    To setup a promiscuous mode policy, either select from the drop down list located in the Network Settings dialog for the network adaptor or use the command line tool VBoxManage; for details, refer to Section 8.8, “VBoxManage modifyvm”.

    Promiscuous mode policies are:

    • deny (default setting) which hides any traffic not intended for this VM's network adaptor.
    • allow-vms which hides all host traffic from this VM's network adaptor, but allows it to see traffic from/to other VMs.
    • allow-all which removes all restrictions - this VM's network adaptor sees all traffic.
  • There is no virtio on ESXi. Using vmxnet3 has already been suggested. – Gerald Schneider Nov 8 '18 at 8:05
  • @GeraldSchneider are you sure? vmxnet3 is a paravirtualized NIC which is probably virtio. And I also give other suggestions for improving performance – phuclv Nov 8 '18 at 8:07

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