Dual NICs in my servers on a differnet subnet for backup purposes?

[scauffiel]

Hey guys, just had this thought while watching football (yeah, I dunno) and am heading out right now so I can't really put a lot of thought to it just yet, but wanted to put it down somewhere to come back to later - and what better place than here for that AND for other informed opinions on it?

Here's what I was thinking; most of my windows servers have dual GB ethernet cards that aren't doing anything, they're there in case something happens to the first card. But what if I were to just connect them to a gig switch, giving them a different IP address than the "usual" subnet. (So if my usual subnet is 192.168.10.x, I'd give these NICs a 192.168.20.x range or something) The whole idea behind this is to use this subnet as a way to run backups and such without dragging down bandwidth across the active subnet. They'd just be talking to each other, don't need to get to the 'net from that subnet, nothing other than a more direct pipe directly to the servers that are used for storage and backup.

I'm just not sure how I'd tell the backup/sync software to use those NICs over the others, but hopefully there's a way to do that.

I need to think about this some more when I'm not out with the little lady, but figgered I'd throw it out here while I'm gone to see what turns up. I'll check back later, probably tomorrow.

Steve

 

[Emulex]

usually you team the two nic's to a switch so if one fails, (wire,port,nic) the other takes over, it can also increase in some cases i/o speed.

Vlan's can split the traffic if you feel like setting them up.

The only big big big gotcha is AD/WINS/SMB - your idea is solid - separate physical switch for backups to not overload the other side - you need to make sure if you use windows that it does not try to advertise traffic on one physical segment to the other machines - otherwise they will try to connect and kaput.

Also windows naming - typically you use a different name for different ip subnets to the same machine - google about how windows servers get pissy about their naming conventions and shares.

I think for beginner network design AKA easy - you have it nailed - no vlan b/s - a cheap quality switch (procurve 1810G-24) can handle quite a bit of traffic. In a pinch a cold spare can be busted out by the receptionist and wired in (not so much if you have more complex vlan setup).

I take it your a small shop - it's okay and not a bad solution at all.

Try to use quality switches - web managed at the minimum so if a bad cable or whatever starts choking up your network you'll have some insight to the problem.

Be very careful if you use active directory - it is easy to make a big mess with dynamic dns and multiple subnets. I try to tell small companies to plan their ip allocation - and if they do not need more than 1 subnet - avoid it to start - until they have someone to manage the AD/DNS/WINS that has the skills. K.I.S.S.

If you want to make it even simpler - stick to the setup you have 1 subnet - teamed nic's for extra safety and a beefy enough switch (redundant power supply, fast) and you probably won't have any issues.

I ran 40 pc's and 20 server's nightly backups (10pm-6am) full backup bare-metal non-incremental 7 days a week - without sweatin' a 2510G-48 procurve - no problemo. If i had the extra cash i'd have gone with the 2910al-48 with RPS but thats a very very expensive solution.

the dude before me (job) tried to setup the AD/file/print servers just like you said - and it was giving out both ip's to the dhcp clients(users) so they'd get some whacky network issues because the servers were advertising on both subnets but obviously one was not available to the users - It was not pretty. Easy to setup - easy to mess up.

wireshark can be your friend

 

[Nothinman]

Hey guys, just had this thought while watching football (yeah, I dunno) and am heading out right now so I can't really put a lot of thought to it just yet, but wanted to put it down somewhere to come back to later - and what better place than here for that AND for other informed opinions on it?

Here's what I was thinking; most of my windows servers have dual GB ethernet cards that aren't doing anything, they're there in case something happens to the first card. But what if I were to just connect them to a gig switch, giving them a different IP address than the "usual" subnet. (So if my usual subnet is 192.168.10.x, I'd give these NICs a 192.168.20.x range or something) The whole idea behind this is to use this subnet as a way to run backups and such without dragging down bandwidth across the active subnet. They'd just be talking to each other, don't need to get to the 'net from that subnet, nothing other than a more direct pipe directly to the servers that are used for storage and backup.

I'm just not sure how I'd tell the backup/sync software to use those NICs over the others, but hopefully there's a way to do that.

I need to think about this some more when I'm not out with the little lady, but figgered I'd throw it out here while I'm gone to see what turns up. I'll check back later, probably tomorrow.

Steve

As long as the backup software uses TCP/IP it should just take the proper route based on the system's routing tables. However, I've always considered Windows to be pretty flaky when it's dual-homed. And as Emulex says you'll have to look at each service individually and make sure that it's setup and working properly on whatever networks it's supposed to be on.

 

[imagoon]

The same issues pop up when you are using dedicated networks for iSCSI also. You have to be 100% certain to tell windows not to register the inaccessible ranges in DHCP. It is well worth the time to make sure that things like IIS / DNS / DHCP etc do not respond on the second inaccessible network for the reasons stated above.

 

[spidey07]

I'll 3rd or 4th the nightmare you'll run into with windows naming having the machine dual-homed like that. It can and will work very well like you want, but you have to make sure windows doesn't try to register the other network interface with DNS/netbios. If you google windows dual-homed server you'll get lots of info on the bad stuff that can happen and how to avoid it.

Also make sure the server doesn't have a default gateway for this interface. Just an IP and netmask.

 

[scauffiel]

Thanks for all the info guys - definitely gonna do some more research on this! I appreciate it!

S.