ProLiant Servers - Netservers

Network performance issues Proliant Servers when TCP offloading enabled

Marco Janse
Occasional Contributor

Network performance issues Proliant Servers when TCP offloading enabled

We have been experiencing a lot of network performance issues on Proliant DL360/DL380 G4 and G5 servers when the default network configuration is enabled.
Issues arise on webservers for example with loading content from another application/database server. Also file transfers between servers were sometimes slow
On some DL360 G5 servers we also experienced random ASR's on a regular basis. (at least once a day but sometimes more that 5 times a day)
After doing a network capture with wireshark, we notice a lot of lost segment warnings and malformed packet errors in the expert info.
Latest drivers and configuration software for the NICs didn't result in any improvements.

The solution to all the above mentioned problems was to disable the following advanced settings of the NIC's, using the HP Network configuration utility:
-Flow Control *
-All TCP and IP Checksum Offload settings *
-Large Send Offload *
-TCP Offload Engine *
-Receive Side scaling *

*settings may vary depending on NIC and driver version

On all servers where we disabled these settings, we saw an immediate improvement in performance. On the DL360 G5 servers where we had ASR's,
we never had another ASR after disabling these settings.

Most of the servers we had these issues were running Windows 2003 SP2, but we also experienced these issues on Proliant servers running RedHat
Enterprise Linux 5.3

Network interface was always the HP NC-Series Broadcom Gigabit model.