Uploading files to content library using vSphere Client may report reduced transfer rate

Products

• VMware vCenter Server
• VMware vCenter Server 8.0

Issue/Introduction

• Content Library file uploads reporting low transfer rate using vSphere Client session to vCenter Server
• Issue is not seen while uploading the file with CLI (PowerCLI etc)

Cause

HTTP/2 can be slower for large transfers on connections with high round-trip time as there is stream level flow control. Each stream has a default window size (64KB), which limits how much data can be sent before waiting for an acknowledgment.

Elevated round-trip latency between the client and server increases the sender's idle time awaiting TCP window updates, thereby constraining throughput and degrading upload performance.

Resolution

Option 1:

To optimize performance, identify and mitigate the underlying causes of round-trip latency within the network infrastructure.

Option 2:

Proceed to implement the workaround to increase the initial_stream_window_size on vCenter Server

• • Log on to vCenter Server Appliance (VCSA) using ssh
  • Execute the below commands:

cp /etc/vmware-rhttpproxy/listeners/edge.json ~/edge.json

cat ~/edge.json | jq 'walk(if type == "object" and has("http2_protocol_options") then .http2_protocol_options.initial_stream_window_size=8388608 else . end)' > /etc/vmware-rhttpproxy/listeners/edge.json

Note: The value "8388608" refers to 8 MB

• • service-control --restart rhttpproxy