I have a linux box with 2 nic cards on it one for prod and one for backup.
My question is while the backup are happening how do I determine which nic is used for backups . I would like to run a command so that that I can see the usage in a dynamic fashion.
netstat(1) netstat(1)
-i Show the state of network interfaces. Only the
interfaces that have been configured with an IP
address or the plumb option using the ifconfig
command are shown. The output includes both
the primary and logical interfaces. (See
ifconfig(1M)). The counts for Ipkts and Opkts
fields are for IP packets only. This option is
ignored if the -p option is specified.
-I interface Show information about the specified interface
only. This option applies to the -g and -i
options.
---------- Post updated at 02:19 PM ---------- Previous update was at 02:18 PM ----------
lsof will verify where what process has what socket open to.
IDeally during the backups the data should be pushed only through backup nic. I dont think netstat will confirm that.
Lsof will tell you where it connected, and if routing is doing the interface selection, you can traceroute the IP to ensure that is working. I am not that often able to play with lsof, but it may tell you enough about the connection. Also, the backup stats should change little or none until you start backup.
What makes you think netstat won't allow detecting the most active nic ?
Do both have a route to the backup server? Are they on different subnets? iptraf will help if you have it installed
what makes you think the backup is the least active? Ideally it should be, but one should really try for more solid information than that.
Is it possible to see which interface a network socket is bound to, once you open it? If so you could open a do-nothing socket to the backup system and check which interface it used...
Nothing, I actually expect the opposite, i.e. the backup being happening on the most active link but of course, all of that depends on what services are provided concurrently to the backup. In any case, it is unclear what problem the OP is trying to solve.