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Applying Best Practices

Configure Multi-Stream Parameters

Replication over WAN related settings are saved at the following registry key:

[HKEY_LOCAL_MACHINE\SOFTWARE\Arcserve\Unified Data Protection\Engine\Network]

The following list displays the Registry key and their default value:

• "WAN_EnableAutoTunning"=dword:00000001
• "WAN_ChunkSizeByte"=dword:00001000
• "WAN_NumberofStreams"=dword:00000005
• "WAN_MultiStreamsMaxCacheSize"=dword:01000000
• "WAN_SendCommandFragDataMerged"=dword:00000001
• "WAN_RTT_Threshold"=dword:00000032

The following description describes the registry key settings:

WAN_EnableAutoTunning

Specifies the switch to enable or disable multiple streaming. If the value is 0, multi-stream is disabled. For other values, multi-stream is enabled. The default value to enable multi-stream is 1.

WAN_ChunkSizeByte

Specifies the data chunk size for each packet. Packet size affects the throughput. If the WAN bandwidth is higher, the data chunk size can be increased higher.

The default value is 4k byte. The range is limited from 512 byte to 1M byte in code.

WAN_NumberofStreams

Specifies the number of streams that needs to be created on WAN, when the latency is more than the WAN_RTT_Threshhold number. The default stream number is 5. The stream range is from 1 to 10.

WAN_RTT_Threshold

When RTT is greater than WAN_RTT_Threshold, multiple sockets are created. The unit of WAN_RTT_Threshold is millisecond (ms). The default value is 50 millisecond. The range is limited from 20 ms to 600 ms.

WAN_MultiStreamsMaxCacheSize

Specifies that the memory size will be allocated when the multi-stream is enabled. This memory buffer will be used to cached received fragged memory. The range is from 16MB to 64MB. Default value is 16MB. If the value is zero, the value will be set to 64MB. The unit of this value is BYTE.

WAN_SendCommandFragDataMerged

Specifies that if the value is not zero, the communication library groups small files and send them in one chunk. If the value is zero, then small files are sent individually. The default value is one.

Notes:

• In a replication job, the socket connection number may not be consistent with the WAN_NumberofStreams registry.

  Replication job from non-GDD to non-GDD

  When RTT is more than WAN_RTT_Threshold, the socket connection number is equal to WAN_NumberofStreams.

  Replication job from non-GDD to GDD or GDD to GDD

  There are four types of connections. Only the data block connection works with the multi-stream feature. So, when RTT is more than WAN_RTT_Threshold, the total socket connection is 3+WAN_NumberofStreams.

• Replication job detects the network status to determine whether the communication is on WAN or not. If the network status is weak, LAN may be accepted as WAN.