High availability is an architectural consideration often involving degrees of redundancy to insure availability in case of system or component failure.

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Managed LAMP platform for maximizing availability and global reach, not scalability

Assume a Linux/Apache/MySQL/PHP application for a small base of registered users. With small userbase, there are no traffic peaks so the scalability that cloud platforms offer is not imperative. But ...
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7answers
886 views

Questions about single point of failure for small operations

If you can't afford or don't need a cluster or spare server waiting to come online in the event of a failure, it seems like you might split the services provided by one beefy server onto two less ...
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2answers
941 views

Xen Remus setup

Currently, I'm running the IT for a small organization, and we just purchased a new server to replace our aging Dell poweredge. As the Dell isn't so bad as to be junk, I was hoping to set up Xen on ...
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JBoss EAP 6.2 high availability without HTTP server

i'm looking for some solution to make a Jboss Cluster ( 2 nodes ) in H.A. ( 1 live, 1 backup) but i don't want to use a third element ( machine, service or whatever ). Most configuration I found uses ...
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3answers
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What is the definition of High Availability?

As far as my understanding goes the availability of a service or system is defined as: (Time resource was available - Time resource was unavailable) / Total Time My questions are: Is describing ...
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46 views

Zabbix web interface says Zabbix server is offline when failing over to passive node

Two Zabbix 2.4 servers using CentOS 6.6 with an external MySQL DB, both servers are configured to connect to this DB when they are running. I followed a combination of Zabbit High Availability guide ...
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2answers
303 views

IBM V7000 firmware upgrade effect on mounted LUN

We've IBM storwize V7000 Storage where the firmware is going to be upgraded to latest version.. This will require a reboot to the storage. I've got arround 10 LUN's (almost 10TB) coming from this ...
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1answer
21 views

How can I host a webservice with real ha on multiple sites? [closed]

I want to create a real high availability environment and eliminate the singe point of failture for our webservice. My idea was to host the service on my companys local enviroment (where it is ...
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1answer
18 views

POST of large file is timing out, when running through ARR

When POST'ing a large file through ARR, the request times out after 120 seconds. The client recieves error code 502 Bad Gateway. I have configured the "proxy timeout" of the web farm to be 600 ...
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1answer
33 views

Single Nginx Load Balancer for 2 different clusters (web, api)

I was wondering if it was possible to use a single Nginx server to load balance my web servers and api servers if both are using port 80. In this setup there would be 5 servers, 1 Nginx and 4 Apache ...
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1answer
833 views

MySQL HA and Magento DB

Is it possible to use MySQL cluster for Magento DB? I have Web app developed in Magento E-commerce platform and I want to make DB highly available using the MySQL cluster. Magento supports only InnoDB ...
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26 views

Load balance and contingency server

everyone. I'm having trouble setting up a load balancing/contingency server. My scenario: I have 2 servers (Windows 2012 R2 machines) to run an application in ASP.Net/C#. My problem: Would I like to ...
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Replicating a linux web server

I'm planning on replicating a web server for high availability purposes. The server is running as a Ubuntu 15.04 virtual machine in Hyper-V and has MariaDB 10.0, Apache 2.4 and PHP-FPM 5.6 installed. ...
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1answer
1k views

MySQL cluster for Drupal?

We have a pretty busy site based on Drupal and I was thinking of introducing some form of clustering for HA and Load balancing. However, http://drupal.org/requirements says: Drupal supports MyISAM ...
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1answer
45 views

How can I deal with failures when connecting to a MySQL cluster?

Our company has created two MySQL servers that are kept in synch using a master-master strategy. The two-machine cluster is managed using crmsh. This is only a high-availability cluster, meaning that ...
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1answer
912 views

unable to destroy windows 2008 r2 failover cluster after SAN rebuild

I created a windows 2008 r2 failover cluster for a sql 2008 active/passive cluster. This two node cluster was using a SAN device for a quorum disk resource as well as MSDTC resource. Well....I ...
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3answers
154 views

SOA architecture requires 99.9% availability -> 9hrs max downtime -> physical architecture mapping?

External architects have designed an architecture for a Service-Oriented Architecture environment. They fixed the availability to be 99.9%, equivalent to max 9 hrs downtime [per year]. Where can I ...
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15 views

SQL Mirroring with Certificates and Domain?

We're replacing all our servers and wish to migrate a mirrored database running in one domain to the new servers in a different domain without downtime. Is it possible to turn off mirroring in the ...
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1answer
974 views

Keepalived not honoring nopreempt

I'm using Keepalived to manage two Redis instances in a master/slave configuration. I'm experiencing a situation where, if Keepalived is terminated on the Master box (the one with the higher ...
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Solving an asymetric HA Firewall/router

I have an old Linux HA firewall/router setup that never quite worked. As it was never quite put into true production (just testing and demo's), I always had to have one firewall shutdown to make it ...
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1answer
120 views

Why to use fencing when you already have redundant communication links?

This article stays that you should use both fencing (aka STONITH) and redundant communication links. I'm trying to understand what benefits STONITH gives in case of split-brain. Consider for example ...
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1answer
163 views

Why Failover instead of Load Balancing for HA

From my understanding with failover clustering, only one machine is actually working, which means the other one(s) are sitting idle. So why would one use failover clustering instead of using a load ...
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1answer
47 views

Creating High Availability Netflow Collector

I'm currently working on replacing our existing Netflow collector that is EOL with a new one. The goal is to support around 4 million flows/minute and have HA capabilities. Below is my initial ...
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22 views

How to setup user accounts on a secondary server in High Availability?

Working with two Microsoft SQL 2012 servers in Always On High Availability configuration running on Windows Server 2012 R2. Setup works well and failover is almost flawless. However, the software ...
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1answer
88 views

High Available SQL Server without SAN by using AlwaysOn feature

I have two Microsoft SQL Servers (v 2012) and I want to make them mirror and when one of them goes down the second one will be replaced. AlwaysOn is a new feature in SQL Server 2012 that is ...
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15 views

Ucarp on vlans in trunk - debian

is it possible to use ucarp on vlan interface in debian ? I am trying : auto eth1 iface eth1 inet static address 192.168.0.1 netmask 255.255.192.0 auto eth1.10 iface eth1.10 inet static ...
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Restarting failed hosts on VMware vSphere ESXi

When a cluster is configured for High Availability (HA), VMs can be restarted onto an alternate host when the its host has failed. However, I am wondering: if the host has failed, is there a means ...
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RHEL KVM HA rgmanager

I have a RHEL HA 2 node cluster which is run with rgmanager, cman (corosync), clvmd, gfs2 and storage replication using drbd I let drbd, clvmd and gfs2 be managed by rgmanager, but i have 8 ...
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66 views

CentOS 7 Cluster with load balancer

I'm trying to understand how clustering works in CentOS 7. I'm not a cluster expert!!! What I'm trying to do is to have three clustered services: httpd, mariadb (mysql) and postgresql. I've managed ...
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corosync is not in sync

Could you please help out show me how to form a cluster? corosync & pacemaker are used. two nodes rac0 ip 192.168.0.140 & rac1 ip 192.168.0.142 They are not shown in each other. They are ...
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1answer
98 views

What design considerations should go into a proper Bitcoin exchange (or any other automated online trading system)? [closed]

Following the epic fiascos of the two main Bitcoin exchange sites (Mt.Gox, which went offline due to sheer traffic load during the worst market crash in the history of Bitcoins, leaving people with ...
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Run generic Windows Service with affinity for the Primary Replica of an SQL Server AlwaysOn Availability Group

Is it possible to configure a generic Windows service in a Windows Server Failover Cluster such that the service always runs on the same machine as the Primary Replica (read/write) of an SQL Server ...
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63 views

ipt_CLUSTERIP: unknown protocol 1

I am trying to create a web cluster with two load balancers and a single public ip address The command I use is the following: iptables -I INPUT -d $CLUSTERIP -i $WAN_IF -j CLUSTERIP --new ...
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60 views

Convert existing servers to a failover cluster

We have ourselves quite a quandary right now. For some time, we've been planning on setting up a failover cluster for our existing servers. The plan so far has been to set up a 2-node GlusterFS ...
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1answer
140 views

Keepalived + Haproxy performance, apache or nginx? [duplicate]

I have a question about Keepalived + Haproxy. At work I am assigned to deploy a redundant web server with Keepalived and Haproxy. Our setup at the moment is as follows: Apache (as load balancer) + ...
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55 views

How to let Corosync / pcs control nginx?

Folks, I'm trying to replace a single aging load balancer with multiple virtual machines running nginx. However after I got centos 7 and nginx installed I realized that heartbeat has been ...
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59 views

Is it possible to prevent pcs/dlm/crm from fencing the node when it fails?

Is it possible to prevent pcs/dlm/crm from fencing the node when it fails? I use cluster only to be able to build GFS2 storage, and there's my own way of avoiding split-brain. So I do not need things ...
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101 views

VMware High Availability questions

I can't seem to find the answers to these questions within the vSphere 5 Documentation center, so please share if you are aware of any aspects of these questions. What happens to the failed VM that ...
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33 views

Apache mod_jk LB synchronization server startup + application startup time

after a long search I can´t found a solution or path to solve my problem with synchronization startup of Apache and Backend servers. I have a Apache2 using a LoadBalancer with mod_jk that balance ...
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1answer
23 views

vmWare HA Admission Control configuration

In an HA cluster of 5 hosts (100GB memory) if Admission control is enabled and %age cluster failover option is set at 25 % (lets consider only for memory ie. 125 GB), and if one host fails then the ...
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1answer
104 views

keepalived multiple instances

I have two application servers running keepalived that are both using keepalived on the same network. I keep seeing Jan 8 11:49:01 <server> Keepalived_vrrp[13764]: bogus VRRP packet received on ...
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111 views

Redundant Debian Gateway

I have to configure a redundant gateway with Debian boxes and I would like to get some recommendation what's the best solution in my case. There are certain limitations in my setup and I have to go ...
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1answer
79 views

Active/Passive Reverse Proxy with nginx

I have two Websocket servers which working with Zookeeper & Curator as Active/Passive, if one server fails then second backend comes alive. I configured it the following way: upstream backend { ...
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3answers
2k views

XenServer HA (failover VM's) without shared storage

In the university from Uruguay where I work, we have 2 IBM BladeCenter S with 4 server blades each one. Each blade have XenServer 6.2 installed and working. Our idea is have each BladeCenter in ...
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34 views

Strange haproxy behaviour

So I'm trying to set up a dual site haproxy (1.5.10) on Ubuntu 14.04. http://i.stack.imgur.com/EtdYo.png When I do service heartbeat restart on eartha, both machines go green briefly; then earthb ...
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33 views

Multiple Subversion Servers behind a load balancer

I'd like to add a little redundancy to my subversion setup. I'd like to have multiple servers share a common NFS mount and load balance http requests to the servers (with stickiness). Is this an ...
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69 views

Which method can I use to automate DNS-failover with monitoring?

We're operating multiple redundant servers across the world for latency reasons. Currently if one site goes down, our only way to let another site take over that region is through DNS. We would like ...
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242 views

How common is it to use additional dedicated servers for redundancy?

I'm new to handling the infrastructure for production service deployments. My intuition tells me that if I want to have my service be "up" as much as possible and yet can only afford say 2 dedicated ...
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Building the infrastructure to support a web application

I am building infrastructure to support a web application. I think I have a decent idea of what the infrastructure should look like, here's what I have: 2 x 16GB, 4-Core HAProxy servers for load ...
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127 views

High availability NFS

We're considering hosting a web application on Amazon AWS. I've drawn a proposed setup for it, which I will try to summarize in a few lines: The web application is served from webservers in 3 ...