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Author Topic: NLB and Load Balancing  (Read 1929 times)

wraith808

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NLB and Load Balancing
« on: November 14, 2013, 09:31:10 AM »
Has anyone had any experience with NLB?  Just wanted an overview from someone that I trust about what my NOC is getting me into.

(And the presentation is really boring and is an overwhelming amount of information to be handled in an hour presentation)

40hz

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Re: NLB and Load Balancing
« Reply #1 on: November 14, 2013, 10:57:37 AM »
It's a well established technique and it works quite well as long as it's set up properly and tuned correctly.

I'm more familiar (from a hands-on 'real' as opposed to 'lab' perspective) with automatic failover provisioning, which is a sorta distant cousin to NLB. The few clients I have that are into serious digital on-demand media distribution (a case where NLB really comes into its own) farm it out to distribution services and let them worry about it.

Sorry I can't be more helpful. SJ is probably the man to ask. Or Gothi[c].
« Last Edit: November 14, 2013, 11:03:42 AM by 40hz »

Stoic Joker

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Re: NLB and Load Balancing
« Reply #2 on: November 14, 2013, 11:22:59 AM »
There's not a lot of call for that class of infrastructure in the SMB market around here. While I do remember quite a bit about it from the Win2k exam track (it was covered extensively), I don't really have any practical hands on with it.

However on the bright side, if you give us a thumbnail sketch of what is being proposed...40 and I can walk you through some of the theoretical stuff.

wraith808

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Re: NLB and Load Balancing
« Reply #3 on: November 14, 2013, 12:09:30 PM »
Basically, we have internal services that are being accessed from client machines, whether they be true clients, or loaders of information from external sources.  In order to increase our ability to handle the throughput from the clients, they are going to farm servers.

These services fall into four categories:
- WCF WF4 services
- DCOM components (that might or might not be enlisted in DTC transactions)
- Appian process endpoints
- ASP/ASP.NET services

From what little I understand, there's no central pooling mechanism- it's sort of peer other than the one specialized switch?  As I'm working from the development side, I'm most concerned about troubleshooting (especially in the case it is an intermittent problem which could indicate a problem with one of the nodes) and deployment and testing.

I feel a little better based on the last 5 minutes of the presentation, even though he didn't go into enough detail on that part, which had to do with gracefully removing a server from the pool and direct connection capabilities to a single server.  But in all reality, it was very overwhelming, especially as this isn't something that I'm going to be directly involved with on a day-to-day basis to bridge the receiving of the information to practical use.

40hz

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Re: NLB and Load Balancing
« Reply #4 on: November 14, 2013, 02:13:05 PM »
Yoikes! That sounds more than a little outside my area of expertise or experience. I doubt I could do more than toss out a few generalities about load balancing on that one as given. ;D

Stoic? You maybe wanna tackle it? :)

x16wda

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Re: NLB and Load Balancing
« Reply #5 on: November 14, 2013, 08:05:43 PM »
We implemented Microsoft's NLB freebie for an Exchange implementation a year or so ago.  The company wanted redundancy so we spun up two CAS servers with NLB in front (plus two pairs of mailbox servers in a DAG, but NLB is irrelevant there).  It's free, but is very basic in that it does not guarantee session persistence to a particular node.  A lot of applications are OK with that, others aren't.  A few years back we put a Big IP box up in front of a web app because the application vendor insisted on load balancing and stated the application needed the session persistence.

It sounds like you have a front end box (the specialized switch?) to do the load balancing, hopefully it'll handle that.  Should make troubleshooting a little easier if the client connection is sticking around on one machine.
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wraith808

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Re: NLB and Load Balancing
« Reply #6 on: November 14, 2013, 08:40:21 PM »
Yes... I guess.  At least, they said that if we were connecting to SomeServerCluster with n number of servers, if we needed to test a particular server, we could connect to SomeServerCluster-onlyserver1 and guarantee what we're connecting to.  But yeah... they said something about it doesn't know the state, so can't guarantee what is being connected to- it's largely round robin and based on availability than truly load balanced.  And they did mention that bit about session persistence in relation to DCOM, which seems a bit scary considering how DCOM works.  But when you use a 16 year old technology (I really wish we could deprecate that) you have to be willing to deal with/expect a few scary moments...

Stoic Joker

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Re: NLB and Load Balancing
« Reply #7 on: November 15, 2013, 07:13:16 AM »
Yoikes! That sounds more than a little outside my area of expertise or experience. I doubt I could do more than toss out a few generalities about load balancing on that one as given. ;D

Stoic? You maybe wanna tackle it? :)

Zoiks! That one is out of my range as well. IIRC everything session wise pivoted on the quorum drive so it would be available to the next machine as/if the load shifted due to a spike or outage. But specifics regarding how to get legacy apps to play nice in that environment I'd be afraid to guess. The Quorum drive sits on the SAN and is the session/connection holding (center of the star basically) area for the front line and backend systems.

NLB over simplified is just an isolated IP network between backend systems that handles only heartbeat packets allowing servers A, B, & C to know if one of them goes down, comes back up, or gets overloaded so they can respond accordingly. The response is/would be to either pluck or hand off some of the machine X session workload which is pooled in the quorum.

Sorry wraith, that's all I got.

wraith808

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Re: NLB and Load Balancing
« Reply #8 on: November 15, 2013, 10:22:11 AM »
Well thanks for the insight in any case :)  Hopefully it won't be an issue.  :-\