[THIN] FW: info HP/Proliant performance problems.. solved
- From: "Ruben Spruijt" <Ruben.Spruijt@xxxxxxxxxxxx>
- To: <thin@xxxxxxxxxxxxx>
- Date: Fri, 12 Nov 2004 11:00:08 +0100
FYI
Ruben,
If you have any Servers with HP NC7781 NIC's installed (Hp DL 380's, DL 360's
and others), you may experience excessive retransmits, Outlook hangs, file copy
performance issues, cluster failovers, etc.
Cause:
The driver defaults to "Offload TCP transmit Checksum" and "Offload Ip Transmit
Checksum". This is a performance enhancement designed to relieve the TCP and IP
components of the IP checksum calculation overhead and assign that duty to the
NIC.
Normally this is a preferred method of operation. The HP NC7781 NICS
periodically
miscalculate the TCP checksum. This causes connection timeouts periodically and
more importantly, Outlook hangs between 10 and 20 seconds. With the latest
firmware
and drivers installed, the issue is still prevalent. The box that receives a
response with an incorrectly calculated checksum simply throws the malformed
response away, never delivering the data to the application.
Resolution:
In the Netcard driver configuration dialog box, disable Offload checksum
calculations. This will allow the TCP and IP components to calculate their own
checksums.This change does not require a reboot or involve a service
interruption, normal
change control procedures should of course, always be followed!
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