SUMMARY
Network Interface Errors
ISSUE
Symptoms / Description
If you suspect network connection issues caused by overburdening of the Unitrends Network Adapter from high throughput, you may run the command “ethtool -S ethX | egrep 'errors|failed|collisions' | grep '[1-9]'” where ethX is the active port on the Unitrends device and it returns alloc_rx_buff_failed issues then you have a buffer overflow.
Cause
This is caused by too many requests flooding the Unitrends appliance all at once and can be resolved by allocating more memory to the buffer process. This is a rare issue typically seen if openVPN is used on a very fast connection (approaching or exceeding gigabit speed).
Resolution / Workaround / Execution Process
See what the max value of the interface is, using eth0 as an example:
# ethtool -g eth0
The following is a sample output:
Ring parameters for eth0:
Pre-set maximums:
RX: 1024
RX Mini: 0
RX Jumbo: 0
TX: 1024
Current hardware settings:
RX: 256
RX Mini: 0
RX Jumbo: 0
TX: 256
In this example, 1024 is the maximum RX and TX buffer size for this particular driver, and the current buffer size is 256.
Run this command to make the change on the fly, then monitor for some time to see if the issue is resolved:
# ethtool -G eth0 rx 1024 tx 1024
To make the change permanent, add the following entry to the bottom of /etc/rc.d/rc.local start-up script:
# ethtool -G eth0 rx 1024 tx 1024
Third-Party Sources
http://firewalltipss.blogspot.com/2011/06/how-to-increase-sizes-of-buffer-ring.html