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.

Load balancing is a group of techniques used to ensure that loads are spread between multiple systems. The term is used on networking and server environments, with similar results.

Network load balancing involves using multiple connections or links to spread speed or high demand between those connections. That can be done on backbone links, carrier internet links or even from servers to switches to provide more speed using link sharing.

Server load balancing utilizes hardware (hardware load balancers) or software (software load balancers) to spread the requests destined for a domain or system between various servers behind those load balancers (often named backends). Load balancing ensures that high performance and scalability can be achieved by addition of servers.

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How do load balance servers handle all the traffic?

I'm trying to understand how load balancing works. I have read the basics however I don't understand how a load balancer doesn't go down because of all the traffic. Lets say I have 1 load balance server and 3 regular servers. The 3 regular servers…
Simon
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Redis high availability and load balancing

I'm using Redis for some time and now we want to move to a redundant cluster which would be fault tolerant, highly available and load balanced. I principally use Redis for some PHP web application which stores some process status information (I'm…
Mat
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HAProxy switch to backup on 500 errors and/or server down

I'm setting up an HAProxy in front of only 2 backend servers, with a particular configuration: any request should go to server A; but, if server A returns a 5xx error code, all request should go to a backup server B. When A returns "up", all the…
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nginx - Load Balancer - Considerable lag when upstream node is offline/down

Running nginx 1.0.15 on CentOS 6.5. I have three upstream servers and everything works fine, however when I simulate an outage, and take one of the upstream servers down, I notice considerable lag in response times (additional 5-7 seconds). The…
Mike Purcell
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How to limit number of sessions?

I need a way to track and limit web sessions to a web app. A "session" is loosely defined as the single user browsing the pages of the said web app. I think it can be translated to: a session is defined as a tuple alternatively as…
the-wabbit
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F5 Load Balancer Resends Request On Timeout

Let me preface this by saying I am not a systems administrator, I'm a programmer. Recently, our systems administrators installed F5 load balancers. Since then, I've noticed that any time a request times out and ends up throwing a 500, the load…
Jim D
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Active Directory authentication load balancing and failover

For applications that authenticate against an Active Directory DC, obviously it would be best to just point them to the main domain DNS record rather than a specific DC for failover, load balancing, etc. What are best practices for those…
Derrick
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Multithreading with multi-queue NIC on SMP system

How are packets scheduled from network interface queues to CPUs, then onwards to threads for processing? What needs to be considered when it comes to how packets are hashed across queues, hardware interrupts vs softirqs, CPU/memory/app/thread…
svenx
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External load balancer solutions between EC2 and Rackspace

I have a website primarily hosted on EC2 with the backends (MySql) replicated async to a Rackspace store. I am also planning to have a suite of web server, cache & db on standby at Rackspace in the eventuality that Amazon has an outage. With this…
Quintin Par
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Advantages of Using Nginx or HA Proxy as Load Balancer

In our environment we us both Nginx and HA Proxy on different clusters. Are there advantages of using one over the other? Or, what is the best way to go about load balancing a basic LAMP server cluster?
Jason
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Haproxy load balancing with HTTP Headers

We're using HAProxy to load balance our websocket and comet application. There is one HAProxy and 3 applications running in the back. We use HTTP Basic Auth (and we will use other types of auth in the future, like OAuth) to identify the connected…
Julien Genestoux
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Load Balancing long running TCP connections

I'm trying to research the best way to load balance long running TCP connections for the following scenario: We have multiple servers behind a redundant set of firewalls and clients establish long running (usually 10-15 hours) TCP connections to our…
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DNS performance: Does having multiple secondary NS servers improve performance?

When some domain have primary NS, and several secondary NSes, will clients ask them randomly to reduce the load, or they will hit primary NS only, and proceed to secondary only when primary fails?
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Is Linux Virtual Server old, or is it standing still?

Based on this question: Widely-used load balancing solutions?, LVS may be the right solution for my problem. But when I went to its homepage http://www.linuxvirtualserver.org/, I found that LVS has been updated since Nov, 2008. The world's moving…
Delta76
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How many reverse proxies (nginx, haproxy) is too many?

I'm setting up a HA (high availability) cluster using nginx, haproxy & apache. I've been reading great things about nginx and haproxy. People tend to choose one or the other but I like both. Haproxy is more flexible for load balancing than nginx's…
Alysum