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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multicast address use in corosync

I'm wondering about the purpose of the multicast address in the corosync messaging software : Since we have to bind each net interface with an IP address and a specific port, and each ring communicate ...
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Any problems with having an active/active HAProxy setup with Keepalived

Apologies if this has been asked before, but I can't seem to find much on it. We're going to be using HAProxy to load balance our MariaDB Galera Cluster. All the articles/tutorials I have seen on ...
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316 views

ASA High Availability failover link configuration

According to the Cisco ASA 5500 Series Configuration Guide, Cisco's preferred method of configuring your network for ASA High Availability is as such: They have two switches on External, two ...
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341 views

Fault-tolerant network access to redundant storage in a heterogeneous environment (including Windows)?

We are facing a design "challenge" where we are required to set up a storage solution with the following properties: What we need HA a scalable storage backend offline/disconnected operation on ...
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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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Setup a constant web application availability on Windows Server

I am a part of a team that is building an ASP.NET web system. We need to guarantee, that when the main hosting server with IIS is being updated, web site visitors get the special message that the ...
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SQL Server 2012 Mirroring / AlwaysOn - need for SAN?

There appears to be a great deal of conflicting information about whether or not SAN is required for a Sql Server 2012 Mirroring setup. I currently have an Active-Passive-Witness SQL 2008R2 setup ...
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High Availability Options for MSMQ

We plan to develop a highly available system based on Microsoft Message Queuing (MSMQ). Currently we are collecting high availability options for MSMQ. We plan to use Windows Server 2008R2 as the ...
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What are the exact storage requirements for an AlwaysOn implementation?

We're investigating implementation options for SQL Server AlwaysOn. AlwaysOn is dependant on Windows Clustering, and I have read several articles that state shared storage is no longer a requirement ...
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High Availability and Load Balancing for MySQL and Jetty

I'm about to deploy two distinct systems: A MySQL cluster and a cluster of Jetty web-servers. 1. SOFTWARE I can get more linux servers for the HA/LB, but which software should I use? I'm with CentOS....
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Heartbeat is giving me a heartache

I have 2 Ubuntu 11.04 VM's on which i have installed Heartbeat + apache2 to achieve a "high availability" setup. Heartbeat is up and running on both but im not able to ping the Virtual IP (cluster ip) ...
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656 views

Solution for two-way file-system transparent solution

I need to implement some sort of HA setup where 2 servers need to be able to always be in sync, no matter on which one you write on. The DB part can be covered by a master-master replication setup. ...
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store high amount of photos (150 million) and make available for web [closed]

For a actual project I must setup a high-available storage server who can store and publish (http) 150 million photos in 7 sizes means total 1050 million files. For every photo we need total 200 KB ...
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781 views

What are the advantages of async. database mirroring over transaction replication?

I've primarily a developer, but our organization is small, so I have been tasked with developing a HA strategy for our SQL servers. Currently, I manage our transactional replication to two additional ...
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3answers
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High Availability and Load Balancing with Debian 5.0 (Lenny)

Suppose I have two Debian 5.0 servers and a generic session-based DB-driven website is running on them. Assume that the two DB instances are already clustered. Each server has its own internal IP ...
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397 views

Firewall that supports HighAvailability and Spanning Tree

I'm looking for a firewall appliance that supports high availability and spanning tree. I have two ha-cluster nodes and I'd like to protect them with a firewall. To avoid a single point of failure, I'...
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Installing two versions of MSSQL on a production server?

We've just provisioned a second dedicated server so we can use database mirroring for high availability. The existing server uses MSSQL Express 2005. We have MSSQL Web 2008 and want to minimise the ...
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845 views

vSphere HA - Dealing with storage hba/link failure?

I'm looking at putting in a small cluster spanning two locations on the same campus. The vSphere hosts in each location would have a vSwitch connected to the production LAN, and I'd also be using a ...
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601 views

Does order of servers in nginx config matter?

I have a custom tool which generates a part of nginx config in the following form, for example: upstream backend { ip_hash; server server1:8080; server server2:8080; server localhost:8080 ...
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245 views

What database is easy to maintain and manage in a cluster?

I'm looking for a database (DBMS) that is easy to scale out. I would like to have high availability so I need a multi-master cluster, where the data is replicated to two or more physical computers. I ...
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71 views

connect to my website from multiple external remote sites

I remember seeing a website where I could type in my home page url, and then get a list of a bunch of servers that connected to my url in real time, from all over the world. the report would show ...
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2answers
444 views

tools for geographical redundancy

I'm writing a spec for a high availability application. I need a low budget solution to be able to failover between two data centers. Replicating databases and content I'll be able to manage solutions ...
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2answers
318 views

MySQL Proxies

In a similar line to... http://serverfault.com/questions/35899/mysql-5-1-replication-topologies-multi-master What I'd like to know is whether there are any really good proxies for MySQL out there? ...
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How does systemd decide if a service is ok or not

This question is related to: reliable systemd service for autossh I have a service which uses type=simple. Here the systemd docs: Type=simple (default): systemd considers the service to be ...
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1answer
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Get IP of node running a specific resource when demoting master nodes to slaves

Setup I am setting up a HA cluster for a web application with 2 nodes (2 physical servers): node1 (current master node) node2 (current slave node) Using Corosync & Pacemaker I was able to ...
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2answers
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Configure HA Proxy between Apache and Tomcat servers

Want to configure HA Proxy with my existing structure. Currently I have Apache->Tomcat server. This I want to change to Apache->HA Proxy->Tomcat Server. HA I have configured for Http request. But my ...
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new hyper V High Avaliability setup and SMB 3.0 storage

I am looking at building an new 2012 R2 with Hyper V setup, everything has to be HP hardware. 2x HyperV 2012 R2 servers running 20-30 VMs. These will be dual 6 core xeons with 128gb of ram. 2x 2012 ...
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Simple redundancy setup using two servers in two different datacenters? [closed]

Scope of the question This question is solely about getting a client requesting a domain: example.com to one of the two available servers. How it is handled from there on, is another problem to solve ...
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Exchange 2010 DAG Failover Cluster DNS Issues

I am having an issues with my Exchange 2010 servers. I have two servers that have HUB/CAS/MAILBOX installed on them. They are configured to use DAG failover cluster. I expereienced an issue recently ...
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634 views

Linux HA Heartbeat Virtual IP Switching with domain name linked to it

I have heartbeat set up on two servers like so: Master: 10.15.1.50 Backup: 10.15.1.51 (Virtual IP: 10.15.1.52) So, the master always has 10.15.1.52 as well, but if it goes down, the backup will ...
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Suggestions on providing HA access to an external (fibre) RAID subsystem

We are looking at upgrading our storage capacity with an external RAID subsystem that has redundant (2) fibre controllers, each controller has 4 x 8 Gbps fibre ports. I would like to make access to ...
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1answer
141 views

Monit server went down

One of our developers needs some sort of notification in order to know whether the application is running smoothly or not.And We already decided that we will implement monit in order to get this ...
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Swap DNS entry on failure

I'm building an application that requires high-availability. We currently run: 4 webservers, 2 varnish servers (both with Pound for SSL proxy), 3 Cassandra nodes. The varnish servers are used as ...
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Availability & Scaling : Three Tier or Two Tier

I began working on a three -Physical- tier website (UI:MVC / Application:REST / DB), I've always considered that three tier is more scalable than two (taboo for high traffic websites), but lately i ...
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heartbeat: Bad nodename in /etc/ha.d//haresources [node1]

I'm trying to start heartbeat on Ubuntu 10.04 with service heartbeat start, but getting the following errors: heartbeat[24829]: 2011/11/22_19:31:07 ERROR: Bad nodename in /etc/ha.d//haresources [...
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1answer
332 views

Change hostname on linux ha failover case

I have configured two machines to do a warm standby so that machine 2 can take the ip of machine 1 if that should fail and become its replacement. sadly, thats not enough, i need to change the ...
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LDAP (389 Directory Service) and Pacemaker with Multi-Master

I'm trying to setup a pair of LDAP servers running 389 (formerly Fedora DS) in high availability using Pacemaker with a floating IP. In addition, 389 supports multi-master replication, where all ...
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Veritas Cluster Server for HA for regular user processes

In the past I have used Veritas Cluster Server for HA clusters of Sybase and other databases at large financial institutions. Now I am going to have locally written processes that could benefit from ...
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Exchange & MS SQL high availability

Could anyone suggest how high availability can be achieved for MS exchange and for MS SQL server between two Data centres when one server each is located in a data centre? Users from a siteA connected ...
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load balancing, high availability for webapp setup

We have build a special interest social network and need to setup now the proper server setup for the webapp servers. We have for the webapp 5 physical server available (2xE5645 CPU, 24 GB Ram, RAID, ...
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Implementation of a fully-redundant, high-available iscsi SAN (consisting of n machines) in conjunction with clustered filesystem

a short example of how the infrastructure may look like: 4 servers act as iscsi targets and expose 1x2TB each (every of those servers has a raid10 for the storage, thus 2TB of usable capacity) n ...
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2answers
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Unexpected start of already-primary server processes when heartbeat on secondary is stopped

I've got an active-passive Heartbeat cluster with Apache, MySQL, ActiveMQ and DRBD. Today, I wanted to perform hardware-maintenance on the secondary node (node04), so I stopped the heartbeat service ...
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Tradeoffs between cross-cloud and cross-AZ-single-cloud deployments

We have a educational system (federated microservices that are running mostly on AWS EC2, RDS MySQL and a message queue) that is already distributed across regions, primarily for latency hiding, ...
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crm_mon -E does not run the external-agent on Debian Jessie

Setup I'm currently having a working 2-nodes HA cluster using Pacemaker+Corosync. My nodes are running on Debian 8 (Jessie). Now I would be able to get notified when changes occur in the cluster (...
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HAProxy failing at random times (backend has no server available!)

I have a CentOS 7.1 (x64) droplet configured to load balance between 2 apache/php servers. I have it working perfectly, but randomly throughout the day it reports the following: haproxy[12947]: ...
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171 views

Loadbalancing and HA with SolrCloud?

I have a LAMP Application running with solr 3.x on one server for several years now. Now I am migrating due to heavy load to a setup with two dedicated machines where all services are loadbalanced via ...
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SLES 12 High Availability Cluster - scsi persistant reservation fencing

I'm trialling SLES 12 w/ HAE to run a Fileserver cluster consisting of two nodes. Idea was to use SCSI persistant reservation as a fencing method using the fence_scsi script from stonith fence agents. ...
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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 deprecated....
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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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DRBD + corosync + pacemaker - Servers won't connect after failover

I got 2 servers configured with drbd, corosync with pacemaker. It is all working fine, primary server gets secondary if it fails, and secondary gets primary. But if the 1st server comes up again ...