Diagnose Server Network Card discards
Posted on 2011-09-08
We're running Windows Server 2008 R2 on Dell Poweredge servers. We have about 20. They all have the same network card settings, but some servers are 2950's from a few years ago, others are R710 and others are R510.
All of the servers have 2 onboard NICs enabled with iSCSI support and have the network settings below. However, on every 2950, one of the two NICs has discards for stretches of time that appear during the busiest times on the servers. The servers have an internal C drive (RAID1) and a 4 disk RAID10 set for part of our database (SQL). They also have at least 2 volumes presented by two different SANs via iSCSI. I have updated the drivers to the latest drive available from Dell.
The discards we can see in Perfmon and via our SNMP monitor software. The discards are only on that one NIC, not on the switch they are plugged into. The switch connects many servers, not just these three. The Switch is a Foundry/Brocade 48 port gigabit switch.
I have verifed all ports on the switch have the same settings and I have made the speed and duplex of the ports on the switch and servers be static just in case it was the auto setting.
The only thing that's unique about the port on each server that's having the problem is that it's the port with the gateway. The other NIC is on the same subnet but does not have a gateway.
Can anyone help me figure out why these NICs are discarding so many packets (2000+ per day, sometimes 4000+)? Thanks!
Settings across all servers (if the NIC has the setting):
ethernet @ wirespeed En
flow control Tx & Rx En
interrupt moderation Disabled
ipv4 checksum offload None
ipv4 large send offload Disabled
ipv6 checksum offload None
ipv6 large send offload Disabled
jumbo mtu 9000
locally admin address Not Pres
number of rss queues 8
Pause On Exh. Host Ring Disabled
priority & vlan P & V En
receive buffers 3000
receive side scaling Disabled
speed & duplex 1 GB Full Auto
tcp connection offload (ipv4) Disabled
tcp connection offload (ipv6) Disabled
transmit buffers 5000
vlan id 0
VMQ Look Ahead Split Disabled
Power Management Off