Questions tagged [load-balancing]

Load balancing deal with the techniques involved on using multiple systems to deal with high demands, balancing the load between those multiple systems. Questions deal with networking and server load balancing, using dedicated hardware or not.

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What is the difference between Load Balancer and Reverse Proxy?

I'm not clear about the difference between Load Balancer and Reverse Proxy. They both seems having same behavior: distributing incoming requests to backend servers.
Morgan Cheng's user avatar
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81 votes
5 answers
145k views

Does each server behind a load balancer need their own SSL certificate?

If you have 5 web servers behind a load balancer (such as haproxy) and they are serving up content for the same domain, do you need SSL certificates for all the servers, or can you use the same ...
Derek Gathright's user avatar
70 votes
19 answers
71k views

Is Round-Robin DNS "good enough" for load balancing static content?

We have a set of shared, static content that we serve up between our websites at http://sstatic.net. Unfortunately, this content is not currently load balanced at all -- it's served from a single ...
Jeff Atwood's user avatar
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50 votes
7 answers
74k views

How can I remove balanced node from haproxy via command line?

I have haproxy running as my load-balancer and from the stats web interface that comes with haproxy, I can put a web server into maintenance mode (and bring it back out again) - which is great! ...
isNaN1247's user avatar
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47 votes
4 answers
134k views

How to set up stats for HAProxy?

I can't figure out how to set up stats for HAProxy. This is my configuration: global log 127.0.0.1 local0 log 127.0.0.1 local1 notice daemon #debug user haproxy group haproxy ...
Jan Deinhard's user avatar
  • 2,403
41 votes
10 answers
266k views

Point multiple IP addresses to a single host name

In Windows System, there is this file at C:\WINDOWS\system32\drivers\etc\hosts. This file allows us to default a specific IP address to a host name. The issue now is whether I can set multiple IP ...
Graviton's user avatar
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40 votes
3 answers
21k views

How to make redundant load balancers?

I understand that the purpose of load balancers is to balance load between your servers and keep track of instance health, etc. But what if load balancer itself fails? How do you set up redundant load ...
Sherzod's user avatar
  • 511
39 votes
6 answers
16k views

What is a typical method to scale out a software load balancer?

I often see web app architectures with a SLB / reverse-proxy in front of a bunch of app servers. What happens when the number of connections to the SLB requires too many resources for a single SLB to ...
z8000's user avatar
  • 802
36 votes
2 answers
86k views

nginx: [emerg] "stream" directive is not allowed here

I have the latest NGINX from ppa installed on Ubuntu 16.04. nginx version: nginx/1.12.1 From my understanding, it should support stream and UDP load balancing. But I get this error message: ...
Houman's user avatar
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34 votes
3 answers
54k views

What kind of load balancing algorithms are there [closed]

I was researching different load balancing algorithms for HTTP and I just found 3. Random, Round Robin and Weighted Round Robin. Are there any other options? Thanks Paul
Paul Sheldrake's user avatar
34 votes
2 answers
67k views

nginx automatic failover load balancing

I'm using nginx and NginxHttpUpstreamModule for loadbalancing. My config is very simple: upstream lb { server 127.0.0.1:8081; server 127.0.0.1:8082; } server { listen 89; ...
robinmag's user avatar
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33 votes
4 answers
43k views

What are the Differences between HAProxy and Ngnix in reverse proxy mode?

What are the differences between HAProxy and Nginx when it comes to their abilities as a reverse proxy?
Quintin Par's user avatar
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33 votes
2 answers
30k views

Do HTTP reverse proxies typically enable HTTP Keep-Alive on the client side of the proxied connection and not on the server side?

HAProxy has the ability to enable HTTP keep-alive on the client side (client <-> HAProxy) but disable it on the server side (HAProxy <-> server). Some of our clients connect to our web service ...
LostInComputer's user avatar
31 votes
3 answers
54k views

HAProxy reqrep remove URI on backend request

real quick question regarding HAProxy reqrep. I am trying to rewrite/replace the request that gets sent to the backend. I have the following example domain and URIs, both sharing the same domain ...
Jim's user avatar
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28 votes
3 answers
26k views

Layer 4 vs Layer 7 Load Balancing

I am trying to decide between using a layer 4 load balancing solution for my datacenter or a layer 7 solution. Unfortunately (for my sanity, that is), my use case is simple enough that both solutions ...
Scrivener's user avatar
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27 votes
5 answers
39k views

Hardware vs Software load balancers: Just a cost issue?

If cost were not an issue, would there be any benefit in deploying a software load balancer for web traffic compared to a hardware one?
timmy's user avatar
  • 425
26 votes
3 answers
12k views

How can I deploy a scalable, reliable haproxy cluster on Amazon EC2?

We need some more advanced functionality than ELB provides (mostly L7 inspection), but it's not obvious how to handle things like heartbeat and high availability with something like haproxy using EC2. ...
Don MacAskill's user avatar
25 votes
2 answers
27k views

LVS vs HAProxy, which should I choose?

I am looking for a solution to load balancing and failover strategy, mainly for big web applications. We have many services to be balanced, such as web, MySQL, and many other HTTP or TCP based ...
Mickey Shine's user avatar
25 votes
2 answers
7k views

How is a single IP address load balanced?

I'm aware of "round robin DNS" load balancing, but how can a single IP address be load balanced? Google's DNS servers for example, 8.8.8.8 and 8.8.4.4. Wikipedia's load balancing article states: ...
Torvero's user avatar
  • 414
25 votes
14 answers
4k views

Load-balancer options [closed]

I am looking at a number of possible options for load-balancing. So far, I am constrained to the following options: DNS server load-balancer, balancing to a cluster of tomcat servers, with ...
toolkit's user avatar
  • 402
24 votes
5 answers
46k views

How do I Install Intermediate Certificates (in AWS)?

I have installed private key (pem encoded) and public key certificate (pem encoded) on Amazon Load Balancer. However, when I check the SSL with site test tool, I get the following error: Error ...
getmizanur's user avatar
22 votes
3 answers
26k views

nginx failover without load balancing

I'm having trouble configuring nginx. I'm using nignx as a reverse proxy. I want to send my all requests to my first server. If the first server is down, I want to send requests to second server. In ...
Serhat's user avatar
  • 343
22 votes
3 answers
39k views

HA Proxy - roundrobin vs leastconn

Are there any suggestion on when should I use roundrobin & when should I use leastconn? I am using roundrobin currently and observed the loading of my back-end servesr are not evenly distribution....
Ryan's user avatar
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21 votes
3 answers
39k views

EC2 Update my existing AMI

I'm using Elastic Load Balancing to load balance my Auto Scaling Group, for that I have a private AMI that hold my application server (Tomcat) and my web app deployed to it as war ... Now everything ...
Hadi Salem's user avatar
20 votes
6 answers
87k views

How can I use HAproxy with SSL and get X-Forwarded-For headers AND tell PHP that SSL is in use?

I have the following setup: (internet) ---> [ pfSense Box ] /-> [ Apache / PHP server ] [running HAproxy] --+--> [ Apache / PHP server ] ...
Josh's user avatar
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20 votes
2 answers
21k views

Is it possible to use multiple load balancers to redirect traffic to my application servers?

I'm new to load balancing and I'm wondering if it's possible to use multiple load balancers to redirect traffic to my application servers. I don't really understand how this can be done. Shouldn't a ...
user3790827's user avatar
19 votes
8 answers
3k views

Software http load balancer?

Right now we only have one back-end server per site/web service. I'd be interested to hear people's experiences with various load balancer apps (something that runs on Linux). What would you ...
Mark Renouf's user avatar
  • 1,373
19 votes
3 answers
37k views

When using TCP load balancing with HAProxy, does all outbound traffic flow through the LB?

I am setting up an app to be hosted using VMs(probably amazon, but that is not set in stone) which will require both HTTP load balancing and load balancing a large number(50k or so if possible) of ...
user122875's user avatar
19 votes
3 answers
36k views

Issues with EC2 Elastic Load Balancer DNS and routing

We're trying to run a fairly straightforward setup on Amazon EC2 - several HTTP servers sitting behind an Amazon Elastic Load Balancer (ELB). Our domain is managed in Route53, and we have a CNAME ...
Cera's user avatar
  • 553
19 votes
4 answers
19k views

How to allow elastic load balancer through port 80 in security groups?

I want to temporarily block port 80 for the outside world, but want the load balancer to pass through the firewall (via security group) so it won't see the instance as unhealthy. How can I do that? ...
Liron Harel's user avatar
19 votes
3 answers
16k views

Redirect all HTTP traffic to HTTPS when using the HTTP(S) Load Balancer on Google Compute Engine

I have HTTP/HTTPS Load Balancing set up on Google Compute Engine with 2 Global Forwarding Rules (HTTP and HTTPS). Each rule points to a back-end service with a protocol of HTTP. I want all requests ...
Ryan Leckey's user avatar
19 votes
1 answer
12k views

Keepalive setting for Gunicorn behind ELB without Nginx

Our app's REST API is served by Gunicorn (not behind Nginx) running on AWS EC2 instances with a typical auto-scaling/load balancing setup. The load balancer's idle timeout is 60 seconds, and Gunicorn'...
handsofaten's user avatar
19 votes
2 answers
4k views

Outlook fails to connect to a load-balanced Exchange 2013 cluster through Direct Access 2012 R2

We have a load-balanced Exchange 2013 SP1 cluster, running MAPI over HTTP. Client connectivity inside our own network works just fine, while clients connected over Direct Access does not connect. The ...
pauska's user avatar
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18 votes
1 answer
36k views

How to divert traffic based on hostname using HAProxy?

I've had some initial success with HAProxy setting up a bunch of app servers listening on various other ports. I now have another webserver listening on one port, and i'd like to what changes to make ...
Bosky's user avatar
  • 315
18 votes
2 answers
67k views

Sticky sessions with Nginx proxy

I have an application that's running on two different AWS instances and I'd like to enable "sticky" or "persistent" sessions based on IP so that I can take advantage of web socket technologies in a ...
Himmel's user avatar
  • 411
18 votes
3 answers
18k views

GlusterFS vs Ceph, which is better for production use for the moment? [closed]

I am evaluating GlusterFS and Ceph, seems Gluster is FUSE based which means it may be not as fast as Ceph. But looks like Gluster got a very friendly control panel and is ease to use. Ceph was ...
Mickey Shine's user avatar
17 votes
2 answers
15k views

What happens when a load balancer fails?

Let's say I'm using Amazon's EC2 load balancer. I have it hooked up to two instances (excuse me if my terminology isn't correct). What happens if the load balancer fails? Do both instances fail to ...
SteveGSD's user avatar
  • 297
17 votes
2 answers
43k views

Load balancing & NAT-ing multiple ISP connections on Linux

I have two internet connections from two different ISPs and I need to balance the traffic originating to and from my network between the two ISPs. I am using Debian GNU/Linux. My set-up is like this -...
Baishampayan Ghose's user avatar
17 votes
3 answers
9k views

Is there a way to add more backend server to haproxy without restarting haproxy?

We want to be able to add more backend servers on demand. Right now I don't see a way to add more backend servers to the config file without restarting haproxy.
Jan Deinhard's user avatar
  • 2,403
17 votes
6 answers
13k views

Solution to route/proxy SNMP Traps (or Netflow, generic UDP, etc) for network monitoring?

I'm implementing a network monitoring solution for a very large network (approximately 5000 network devices). We'd like to have all devices on our network send SNMP traps to a single box (technically ...
Christopher Cashell's user avatar
17 votes
1 answer
32k views

Create a multi-homed linux load balancer with two internet connections and one LAN connection

OK,... this has possibly been answered, unfortunately, I have not found anything that looks like it might be the resolution. Ive looked at these pages and they have some useful information, but not ...
John Schultz's user avatar
16 votes
3 answers
33k views

How to setup HAProxy with failover?

I understand that, to get failover on an HAProxy load balancing setup, you need two machines running HAproxy (and route it to several webserver instances). But in this case, say abcd.com, how do we ...
mixdev's user avatar
  • 383
16 votes
2 answers
36k views

HAProxy switch only in case of server down

Let's say I have 2 servers - SA and SB. Is it possible to configure HAProxy to work like this: All connections goes to SA -> SA goes down -> HAProxy switches all connections to SB -> until SB is not ...
Joe's user avatar
  • 323
16 votes
3 answers
23k views

Install AWS SSL Certificate to EC2 instance without load balancer

I'm new with AWS and facing some confusion with ACM SSL certificate installation to an EC2 instance. Is it possible to install the certificate without using ELB or Cloudfront. I don't need load ...
kevenlolo's user avatar
  • 263
16 votes
2 answers
35k views

How does one point a domain to a load balancer that doesn't have a stable IP?

I'm trying to point mydomain.eu to an AWS load balancer, which, by its nature, does not have a stable IP, so I think I'm supposed to point the A record to a subdomain at Amazon, but as far as I can ...
Elver Loho's user avatar
16 votes
2 answers
4k views

Campus Network Design - Firewalls

I am designing a campus network, and the design looks like this: LINX is The London Internet Exchange and JANET is Joint Academic Network. My goal is an almost-fully redundant with high availability,...
user3081239's user avatar
16 votes
3 answers
8k views

Multi-site high availability

We have a SaaS application that we need to be highly available. We already have an expensive, well-maintained Hyper-V failover cluster, but today the datacenter where we host that cluster had a five-...
Mike's user avatar
  • 1,293
15 votes
1 answer
38k views

Basic Weight Questions with HAProxy

Do weights assigned to servers only effect the balance within that particular backend? When implementing weights for the first time, if I give all the servers in a backend the same number, would that ...
Kyle Brandt's user avatar
  • 84.3k
15 votes
2 answers
32k views

What algorithm does Amazon ELB use to balance load?

I found this in the official ELB documentation By default, a load balancer routes each request independently to the application instance with the smallest load. but an article on Newvem says ...
kn330's user avatar
  • 837
15 votes
7 answers
17k views

Wordpress Installation on Two Servers - Loadbalancing

I have to install wordpress (One Blog, one domain, for e.g. mycompany.com/blog) on two servers sharing one database on a different server, these two servers are behind a loadbalancer and the db would ...
Mutahir's user avatar
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