You can set properties to configure the packet size of UDT packets, the buffer size for UDT in source and destination clouds, and the minimum and maximum bandwidth for UDT transfer.

You may need to configure UDT in some scenarios. For example, in low bandwidth networks, if you copy a large object from a private cloud to a public cloud using the UDT protocol, copy might fail. In this case, configure a smaller UDT packet size and update the buffer size accordingly.

Similarly, in high latency and packet loss scenarios, configuring the minimum bandwidth to slightly less than the actual bandwidth available improves copy performance.

You can set the following properties.

UDT Properties

Property

Description

Default Value

Recommended Value

udt_pkt_size

Packet size of UDT packets

1048576 KB

For low bandwidth networks:

1024-1048576 (1KB to 1MB)

udt_snd_buf_size

Buffer size of UDT at the source

10485760 KB

Approximately 10 times udt_pkt_size

The value must be greater than udt_pkt_size.

udt_rcv_buf_size

Buffer size of UDT at the destination

10485760 KB

Approximately 10 times udt_pkt_size

The value must be greater than udt_pkt_size.

udt_min_bw

Sets the minimum bandwidth for UDT transfer, for optimal throughput

1 Mbps

Slightly less than the actual bandwidth available. If the value is too high, performance is degraded.

udt_max_bw

Sets the maximum bandwidth for UDT transfer

0 Mbps

In most cases you do not need to set the maximum bandwidth.

Set the properties in the source and destination vCloud Connector nodes.

1

Log in to the node console as admin.

The default password is vmware.

2

Change directories to /usr/local/tcserver/vfabric-tc-server-standard/agent/webapps/agent/WEB-INF/spring/appServlet.

3

Open the management.xml file in a text editor.

4

Search for property name="udtProperties".

5

Edit the properties.

6

Save and close the file.