Questions tagged [high-availability]

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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Loadbalancer and Tomcat [closed]

Currently we have a single tomcat 7 running as our application server, but with users increasing we were thinking of the following, 1) Put a hardware load balancer 2) Put two tomcat servers on ...
Cool Techie's user avatar
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High availability of http service

I know this has been discussed many times. I read a lot about the subject. Let's say I want to have a failover between http services (a static web server, a load-balancer..) From what I understand, ...
Pierre Ozoux's user avatar
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Why does DFSZKFailoverController kills Namenode process in hadoop?

I try to configure hadoop high availability cluster by following this tutorial: http://www.edureka.co/blog/how-to-set-up-hadoop-cluster-with-hdfs-high-availability/ When I follow that article I faces ...
Oleksandr's user avatar
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Pacemaker: disallow resource on stopped node

I have a slave-ip resource which I'd like to locate on my slave under normal operation in a 2 node PostgreSQL cluster for read-only purposes. All is fine, right till the point of failure of the ...
Frank's user avatar
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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, ...
Jedi's user avatar
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System outage when only one of two HAProxy servers is down. Failover doesn't seem to be working

First of all my experience with HAProxy stack is just one day old so I hope my question makes sense. I have 2 HAProxy VMs and 2 Apache VMs (vagrant machines) as follows. 192.168.50.11 HAPROXY VM1 ...
BentCoder's user avatar
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Disable VM Autostart - XenServer

After running updates in XenServer 6.5 I noticed that some virtual machines that were recently turned off started turning on again automatically after the server I applied updates to restarted. When ...
jrd1989's user avatar
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Linux HA Cluster: running a resource as non-root user

i'm have successfully setup the HA cluster using pacemaker and corosync on centos7, and i've also been able to add and start resources. one of the resources is an instance of tomcat, and in the ...
ksm's user avatar
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Mathematically, how to calculate an uptime percentage based on a number of nodes and their respective uptime percentage?

This question is more of a math question than a server question, but it is strongly server related. If I have a server that I would be able to guarantee 95% uptime and I would put that server in a ...
Jeroen Landheer's user avatar
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Exchange Server 2013, Database Availability Groups, NAT, and High Availability

Dilemma here I want a high availability/failover solution for people accessing outlook anywhere or exchange from outside the network. I have 2 exchange servers (EXCH1 and EXCH2) that have Exchange ...
Kevin's user avatar
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crm status : 0 nodes and 0 resources configured

I've configure corosync and then I got these issue 0 nodes and 0 resources configured. [root@sitampan2 verdana]# crm status Stack: unknown Current DC: NONE Last updated: Thu Jun 16 15:15:40 2016 ...
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Error configuring File Share Witness in a Windows 2012R2 Cluster

I'm learning how to configure a simple W2012R2 Cluster for a AlwaysOn Basic Availability Group. I have this VM scenario: - 1 DC (outside the cluster) - 2 SQL Server Standard 2016 (in a Cluster) I'...
Farlop's user avatar
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DNS issue with Failover IP from Hetzner

Assume we have two servers A and B with 'real' and external IPs and we can switch the so called 'failover ip' (W.X.Y.Z) to point to a specific external IP of A or B. This works from the 'outside' and ...
Karussell's user avatar
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Load Balancing & High Availability Network Limitations

I'm in the process of coming up with a highly available Apache / MySql group of virtual servers using HAProxy Reverse Proxy & Keepalive. I'm aware that I'm going to be using a floating public ip, ...
codex73's user avatar
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HA Swarm cluster with docker-machine

I have a Swarm cluster which currently only has a single master. So far the whole thing has been deployed using docker-machine. I have another node that I would like to use as another master. When I ...
chriscowley's user avatar
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how to cache contents in HAProxy [closed]

global log /dev/log local0 log /dev/log local1 notice chroot /var/lib/haproxy stats socket /run/haproxy/admin.sock mode 660 level admin stats timeout 30s user haproxy group haproxy daemon # ...
Jose's user avatar
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How to use Docker with HAProxy+Keepalived?

I want to practise in creation of high-available web-application using multiple Docker containers on one machine. I launch several web-servers within Docker containers. Say, three servers rest1, ...
Charlie's user avatar
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Cisco 1921, SMTP, and NAT on multiple Exchange Servers

In a LAN environment, I have 3 exchange servers that have been deployed for high availability and failover in case one of the 3 servers becomes unavailable. Currently, my NAT settings only send ...
Kevin's user avatar
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How can I configure a single-node cluster on RHEL 7?

For particular purposes, I'd like to know how can I configure a RHEL 7 HA cluster with only one node (of course, no HA will be available in this scenario). The following article says that single-node ...
Riccardo M.'s user avatar
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Configure STONITH for esxi host CentOS guests

I am just doing some initial researching into STONITH and am finding that it can require Hardware to reset the failed nodes. Something called an IPMI can be used. I was wondering how something like ...
FreeSoftwareServers's user avatar
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Passing SAN Storage to Virtual Machine in active/passive HA Cluster

I need to attach a fibre channel SAN disk to one virtual machine that resides on an active/passive cluster (pacemaker, corosync). As it is the backup storage, corruption has to be strongly avoided. ...
alexander belov's user avatar
4 votes
2 answers
6k views

pacemaker corosync lsb resource script( Sybase database ASE server and backup server)

I'm trying to create a lsb resource with pcs on rhel7.2 The "sybase" script is about Sybase Database ASE Server and Backup Server Startup & Stop & Restart $ status script Before [...
Arthur Cheng's user avatar
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1 answer
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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 started ...
guettli's user avatar
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How to calculate SLA Availability

Imagine that we have an API service with 99,9% of Availability. So this API can be down just 1m 26.4s daily. So how do I measure if an API is down? IMO, i need a sampling rate, in the SLA contract ...
p.magalhaes's user avatar
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Can't start VM OpenNebula

I have 3 nodes with CephRBD + OpenNebula + Corosync + Pacemaker + Galera + crmsh. Software: OpenNebula 4.14.2, CentOS 7.1 All works, but when I instantiate VM, a get an error and VM in PENDING ...
Roman Bogachev's user avatar
3 votes
2 answers
470 views

Hyper-v failover or replication in 2 node cluster

I'm trying to setup some form of a failover cluster between 2 hosts. I want to be able to have high availability on 2 of my VMs. It seems that some form of shared storage is required for this to work ...
phosplait's user avatar
1 vote
2 answers
75 views

Using a load balancer in front of many sites

Is there any reason not to use a software load balancer / proxy in front of many small websites for admin purposes. I work for a web design agency where we have maybe 30-40 small to medium websites ...
anteatersa's user avatar
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1 answer
1k views

Proxmox HA Cluster tiebreaker node

I want to setup a Proxmox HA Cluster using a quorum for reducing the risk for a split-brain. So I need 3 nodes. Is it possible for one of the nodes to just act as a tiebreaker node without running any ...
Michael's user avatar
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Windows 10 Offline Files will not Sync

Brand new domain using Windows 10 workstations and Server 2012 R2 Domain Controllers. Standard folder redirection GPO Picture of the issue: Files are being redirected to a windows 2012 r2 high ...
Nathan's user avatar
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3 votes
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How does High Availability work? [closed]

I don't understand how to setup a failover for my quite simple scenario. I am building a service gateway for API. What I want to have is two servers hosted in different datacenters. And I simply want ...
Wapac's user avatar
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MS SQL - HA & load balancing best solution for servers at different geo-location

Customers has App server (MS Server 2012) and Storage server (MS SQL 2012), with several hundred clients accessing server app via VPN. Now they want to have a high-availability and also load ...
Flanker's user avatar
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6 votes
3 answers
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RDS 2012R2: RD Connection Broker HA - cannot connect to SQL

I have a brand new RDS environment I am trying to set up. I'm trying to follow this guide: https://msfreaks.wordpress.com/2013/12/09/windows-2012-r2-remote-desktop-services-part-1/ and have gotten ...
ITKat's user avatar
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3 votes
0 answers
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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 (...
Habovh's user avatar
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Keepalived - Keep VIP after stop in both nodes

There's any way to keep the last VIP configuration in the case of a daemon stop in all the nodes of Keepalived? Thanks in advance.
Rafael Minguillón Sánchez's user avatar
3 votes
1 answer
5k views

Multi-state MySQL master/slave pacemaker resource fails to launch on cluster nodes

Setup I'm setting up an HA cluster for a web application using two physical servers in a Corosync/Pacemaker managed cluster. After finding out I was heading the wrong way, I decided to use heartbeat'...
Habovh's user avatar
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2 votes
1 answer
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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 ...
Habovh's user avatar
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0 votes
2 answers
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Keepalived heartbeats not being sent/received on EC2 VPC

I'm trying to setup keepalived + HAProxy as a redundant load balancer on an EC2 VPC (yes, I know that ELB is an option). I believe we have things configured correctly, but killing the master server ...
James Simpson's user avatar
3 votes
1 answer
3k views

Two-node VMware HA cluster - admission control policy?

I normally setup larger clusters than a 2-node cluster with shared storage, but we have built a cluster specifically for hardware based GPU's for a few VMs and thus new hardware and just a 2-node ...
TheCleaner's user avatar
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How to make node join the cluster (Pacemaker, Corosync 2 node setup) automatically after disconnection / unplugging?

I have a 2 node cluster running Corosync and Pacemaker. If I physically unplug the network cable on one node, the other one becomes standalone. But when I plug the network cable back in, I want it ...
Arvind Nedumaran's user avatar
-1 votes
1 answer
264 views

SQL Server Failover Clustering (4 nodes)

I think I was able to convince my cow-erkers that jamming all the databases on one server is a good idea. So, our setup will be something like this: Production - SQL 2014 Enterprise Standby - SQL ...
Rob's user avatar
  • 201
0 votes
1 answer
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SQL Server: One Production server be Failover for other

I'm surely using the wrong terminology, but I have the following: SQL Server A (SAN1) - DB1, DB2, DB3 SQL Server B (SAN2) - DB4, DB5, DB6 It's currently SQL 2008 and we're looking to move to SQL ...
Rob's user avatar
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1 vote
2 answers
984 views

nginx multiple frontend servers with SSL DNS setup?

I have my backend app server setup and working with a single reverse proxy nginx setup on the west coast. It also does caching. Now I want to include another frontend server in a east coast region ...
user1669039's user avatar
1 vote
1 answer
1k views

Docker Swarm and Consul production setup recommendation

I'd like to set up a production HA Docker Swarm cluster. Docker Swarm needs a Key Value store as a precondition, consul in this case. Now I'm asking what a clever setup would be: Consul should run ...
binaryanomaly's user avatar
4 votes
0 answers
2k views

How to Reduce Failover Interval in HAProxy?

I have setup HAProxy and it is working fine. I observed that when one of the node goes down HAProxy detects that immediately, but switch-over / redirect existing traffic to the rest of working nodes ...
Never Quit's user avatar
0 votes
1 answer
768 views

How to make Remote Desktop Services Deployment visible in Windows 2012R2 server manager when logging with a different user?

We have an high availability setup for Remote Desktop Services (Windows 2012R2 datacenter edition) all servers are member of "Domain A": 2 Domain controllers : DCA01, DCA02 1 Gateway ...
g0lem's user avatar
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0 votes
1 answer
63 views

How do I setup bonding on Centos 6.x for High Availability? [closed]

My server has two Ethernet ports. With Bonding I setup two different IP addresses for both. The hardware is not very new, so I wouldn't expect that the newest versions of these features to work. ...
Bruce Whealton's user avatar
1 vote
1 answer
164 views

Neo4j HA in Azure Iaas VMs and availability set

I am about to setup Neo4j HA on Azure VMs, what is the best arrangement of the VMs in azure availability set to provide HA for Neo4j. I think if i put all the VMs in one availability set there could ...
Farvashani's user avatar
0 votes
1 answer
224 views

Neo4j HA scale out scenario

Is it possible or even feasible to start Neo4j HA with one master and add slave in high traffic time with some sort of load balancing? From Neo4j Doc : Neo4j HA requires a quorum in order to ...
Farvashani's user avatar
-1 votes
1 answer
211 views

One big server or multiple small? [duplicate]

I run an ad network with about 10 million visits per month. It is very likely that this rate will increase to 50 million in the next 6 months. What is the best way wo scale hardware? Currently I am ...
Max's user avatar
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3 votes
0 answers
69 views

Dell switches, LAG config, ports stay lit when device powered off

I have two Dell switches configured in a stack (with stacking cables). I have four ports on each unit in the stack configured in two separate LAGs as follows: Unit 1/P1: LAG1 Unit 1/P2: LAG1 Unit 1/...
Alan Murrell's user avatar

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