How to troubleshoot high rx discard rates on Procurve switches

[iglablues]

Hi all-

I've been getting alerts in our monitoring system that two ports on my Procurve 5406zl have high inDiscards on one port and high outDiscards on another. The high inDiscard is occurring on a port that is linked to another Procurve, a 2910-al, on its A1 port. The uplink from the 2910-al shows this for show interfaces A1:

Errors (Since boot or last clear) :
FCS Rx : 0 Drops Tx : 0
Alignment Rx : 0 Collisions Tx : 0
Runts Rx : 0 Late Colln Tx : 0
Giants Rx : 0 Excessive Colln : 0
Total Rx Errors : 0 Deferred Tx : 0
Others (Since boot or last clear) :
Discard Rx : 83,723 Out Queue Len : 0
Unknown Protos : 0
Rates (5 minute weighted average) :
Total Rx (Kbps) : 177408 Total Tx (Kbps) : 227736
Unicast Rx (Pkts/sec) : 31065 Unicast Tx (Pkts/sec) : 29568
B/Mcast Rx (Pkts/sec) : 51 B/Mcast Tx (Pkts/sec) : 11
Utilization Rx : 01.77 % Utilization Tx : 02.27 %

The 5406zl shows this for show interfaces D1:

Errors (Since boot or last clear) :
FCS Rx : 0 Drops Tx : 0
Alignment Rx : 0 Collisions Tx : 0
Runts Rx : 0 Late Colln Tx : 0
Giants Rx : 0 Excessive Colln : 0
Total Rx Errors : 0 Deferred Tx : 0
Others (Since boot or last clear) :
Discard Rx : 21,449,090 Out Queue Len : 0
Unknown Protos : 0
Rates (5 minute weighted average) :
Total Rx (Kbps) : 226384 Total Tx (Kbps) : 177072
Unicast Rx (Pkts/sec) : 29455 Unicast Tx (Pkts/sec) : 30978
B/Mcast Rx (Pkts/sec) : 4 B/Mcast Tx (Pkts/sec) : 49
Utilization Rx : 02.26 % Utilization Tx : 01.77 %

I have read that discards usually mean the port buffer is full, but I can't find a way to verify this and since the port utilization seems low I don't understand how this could be. Also, if that is the case, what is the solution? 

Related perhaps is that on the 2910, I also see a number of high Rx discards on an interface connected to a server. That interface is 40, and show interfaces 40 gives me:

Errors (Since boot or last clear) :
FCS Rx : 0 Drops Tx : 14,563,413
Alignment Rx : 0 Collisions Tx : 0
Runts Rx : 0 Late Colln Tx : 0
Giants Rx : 0 Excessive Colln : 0
Total Rx Errors : 0 Deferred Tx : 0
Others (Since boot or last clear) :
Discard Rx : 0 Out Queue Len : 0
Unknown Protos : 0
Rates (5 minute weighted average) :
Total Rx (bps) : 63043864 Total Tx (bps) : 70512504
Unicast Rx (Pkts/sec) : 8122 Unicast Tx (Pkts/sec) : 7033
B/Mcast Rx (Pkts/sec) : 0 B/Mcast Tx (Pkts/sec) : 54
Utilization Rx : 06.30 % Utilization Tx : 07.05 %

Can anyone offer any suggestions about how to troubleshoot this? 

Thanks.