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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SAN storage I/O issues [on hold]

I have a relatively busy application running on a dedicated server. The spec is 8-core Xeon(R) CPU E3-1240 v3 @ 3.40Ghz 16GB RAM 8TB RAID 10 80GB SSD for MySQL I use Wowza Streaming Server to ...
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43 views

DNS round-robin requests not distributed evenly

We have setup two DNS A records, where each points to a load balancer. nslookup ourdomain.com Server: 8.8.8.8 Address: 8.8.8.8#53 Non-authoritative answer: Name: ourdomain.com Address: ...
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15 views

Multi Path VRRP with keepalived

I'm migrating from an old heartbeat setup to using keepalived at the moment and currently I can't find how to replicate the heartbeat capability of using multiple links as cluster interconnects in ...
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23 views

can AWS load balancer auto restart out of service images?

I have set up a load balancer with two instances in two availability zone I set up an health check to ping a specific page of my webapp now I'm trying to find if the load balancer health check could ...
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29 views

Considerations for SQL Server 2012 when performing in-place OS upgrade to 2012 R2

I'm running SQL Server 2012 Enterprise (11.0.3381.0) on Server 2012 (6.2.9200) and am preparing for an in-place OS upgrade to 2012 R2. We've got an Always-On Availability Group in a 2-server cluster ...
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22 views

Gluster FS. Rebuild replicated volume

I am playing with GlusterFS. And now I am curious how to fully rebuild replicated volume. So I`ve created 1 replicated volume from server1 and server2 nodes: root@server1:~# gluster volume create ...
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75 views

How to configure a web hosting server to be tolerant of ISP failures?

We need DNS fault-tolerance for our ISP We host a number of web sites on a local CloudLinux server running cPanel and WHM. The server itself is it's own DNS server. The server lives in our ...
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26 views

SQL 2012 Availability Group Doesn't Failover When Shutting Down Service

I am having an issue with SQL 2012 Availability Groups where it does not fail over when shutting down the service. When you shut down the service you will get an error: A network-related or ...
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13 views

SQL Server 2012 AlwaysOn Availability Groups Server Logins Fails When Switching Between Nodes

I am setting up a 3 node cluster as part of an availability group. Initially I tested failover between nodes using SQL Management Studio and everything failed over successfully when I stopped a node, ...
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47 views

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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26 views

SQL 2012 AlwaysOn Availability Groups Failover Successfully But Application Complains About Login Failed for User

I am trying to get SQL 2012 AlwaysOn Availability Groups working for an application. The cluster has 2 SQL nodes and 1 witness server. Everything appears to be failing over successfully when I do ...
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How does HA / failover work?

Let's say we have ten servers, each one has a copy of stateless application. user enters address in a browser / client program. dns server returns a list of ip (however many people say that dns ...
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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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0answers
107 views

Pacemaker ocf:heartbeat:IPaddr on different subnets

I'm trying to add a Pacemaker virtual IP address; with it, the gateway, and the two VMs it serves on different subnets. I've only done this before with all IPs on the same subnet, and I need some ...
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1answer
73 views

HAproxy mysql failover

I try to set up a HA cluster with Percona xtraDB Cluster for MySQL replication and HAproxy for load balancing. HAproxy works really good with apache, when apache crash or if it's not responding, ...
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20 views

mysql-ha in cloud failover

we have mysql linux 5.6 databases in AWS EC2 and we like to implement a multi region HA solution so we have no downtime and can fail over, what steps tool strategy you suggest?
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i need redis high availability statistics

does anyone have any real life statistics on how long they can keep a Redis instance up and running for? I know I can get Redis Sentinel to give me fail over functionality but what is should be my ...
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43 views

OpenVPN timeout to reconnect on fail takes a long time

I'm trying to create a high-availability environment for my OpenVPN servers. I do this by having two identical VPN servers and in my client config specify multiple remote's: # The hostname/IP and ...
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50 views

Heartbeat fails to start

I have two virtual machines running CentOS 6.6 (I use WMware workstation). I have heartbeat installed and configured on both. The configurations are: /etc/ha.d/ha.cf udpport 694 debugfile ...
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57 views

Why both nodes in OCFS2 cluster keep rebooting?

We created an OCSFS2 cluster by using SUSE Linux High Availability Extensions on SLES SP3. The cluster nodes are two Apache servers which share one disk. We have stonith enabled and SBD daemon. It ...
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1answer
33 views

Can't change source IP address (to floating ip) for udp outgoing packages

I'm having trouble getting a cluster to work using pacemaker and corosync. Here is my hardware configuration: Network: 192.168.3.0/255.255.255.0 Gateway: 192.168.3.1 node1 (Ubuntu Server 12.04 x64) ...
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59 views

Pacemaker ClusterIP stops working after 15 minutes but is still running

I am running Corosync and Pacemaker via a cman stack, in an active-active setup delivering web pages, and I've hit a brick wall. I'm using the IPaddr2 resource agent to have an IP that is used ...
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55 views

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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What is the definition of High Availability? [closed]

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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124 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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69 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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56 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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34 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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3answers
180 views

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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80 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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35 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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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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198 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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71 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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29 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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32 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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45 views

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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115 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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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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86 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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205 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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83 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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129 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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152 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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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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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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131 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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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 ...