Multiple NICs on the same machine?

colm_c

We're going to be upgrading our file server here shortly by taking out the Hard Drive and replacing it with a new hardware RAID array, and also doing a fresh install of Red Hat, while we're at it

While we we're doing this I was thinking of installing a second (or third even) Network Card on the machine, to increase overall access time over the network. Is this a big deal in Red Hat? or will the system get confused with having an IP address for each card? or is it even worth doing for the overall gain in read/write time?

BTW the network has got a DHCP firewall server giving out IP addresses, and also a managed switch

I'd appreciate any information on the above

phil

Is your NIC really the bottleneck here? I'm afraid to say it's testing time and you need to find the bottleneck and then decide on the best course of action.

Linux can handle separate IP addresses on multiple NICs quite easily.

colm_c

There's no bottleneck at all infact it's quite the opposite, the network is zipping along with no problems or slowness at all...

But we've got a few spare NICs hanging around the office, and since we're upgrading the machine anyway, (with the RAID array) I just wanted to find out about putting additional NICs into the machine... and whether or not it would be worth it especially if we are going to have 600GB of space with the new setup...

seamus

TBH, it would be a very complicated setup to get more bandwidth out of it, ifyou only have one subnet.

If you have a couple of subnets though, it could be useful. That is, you have network A and network B.

Your current setup is that A and B cannot see eachother. Network A connects to Router 1. Network B connects to router 2. Fileserver is also connected to router 1, so router 2 connects to router 1, which is configured to forward conenctions from router 2 to the fileserver.

Now, with two NICS, you could arrange it so that both Router 1 and Router 2 are directly connected to Fileserver, effectively giving each Network A & B a dedicated 100Mbps each.

This is just an example obviously. Sounds to me like pointless work for a bored Sys Admin

phil

Adding in a new NIC won't do much. Depending on your network, you could split services between the NICs, but without telling us how your network is setup, what it's serving etc. it's actually pointless speculation.

ressem

It's possible to bond network interfaces
http://www.redhat.com/docs/manuals/enterprise/RHEL-3-Manual/ref-guide/s1-modules-ethernet.html

or
http://linux-ip.net/html/ether-bonding.html

It only gets one IP address and in theory should keep going in case of one nic failing but looks like there were still issues in 2.5 kernels, so depends on what you're using.

If you just want failover then you shouldn't need a special switch, but you do if you require higher speed.

Look for the bonding.txt file in your kernel source's documentation/networking for a proper idea of what's involved.
Also mentions what is required of the switch. (eg Cisco Etherchannel or LACP support)

colm_c

Thanks for the info guys, the file server is only used for just that, storing files... nothing else...

We've got about 10 users on the network at the moment, but the numbers are growing...

the only reason we were thinking of adding a couple of extra NICs was to increase bandwidth access for users so when we add more users to the network other users won't notice any reduction in access to the server...