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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AWS VPC equivalent to CARP across multiple AZs

I'm presently trying to setup a HA MySQL environment within an AWS VPC. The basic setup will involve having a MySQL server in each of the availability zones, with one acting as master and the other ...
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60 views

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, ...
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1answer
15 views

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 ...
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32 views

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 ...
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34 views

Zookeeper can work with Pacemaker?

As mentioned in the title, do you think Zookeeper can work with Pacemaker instead of Corosync? Is there any examination about that? Thanks for your help!
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20 views

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 ...
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1answer
52 views

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. ...
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2answers
57 views

pacemaker corosynce 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 ...
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14 views

PowerHA 7 for AIX 6.1: Modifying the IP source for outgoing packages

I've clusterized a server which has ip address 10.10.10.10/24 (example ip) For that I added two new nodes with ips 10.10.10.11 and 10.10.10.12 and changed the ip 10.10.10.10 to the service IP ...
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1answer
115 views

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
25 views

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 ...
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17 views

Can we make a cpp application as HA using keepalived? [closed]

I have 2 servers running the same c++ application, but the application in master server recieves the calls. Once the application goes down in master, slave becomes master and recieves the calls. This ...
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9 views

Auto Power On Xenserver 6.5

After applying updates to my xenservers I noticed VM's that were turned off turned themselves on after the server I applied updates to rebooted. I do not have any vApps configured and I did not ...
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28 views

How can I configure Consul to health check connectivity from a client node to service nodes?

I'm a Consul and HA newbie and trying to evaluate how I could go about configuring certain requirements in this tool. I want to have a service configured on multiple nodes allowing client nodes to ...
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15 views

Can I run Tomcat with mod_proxy_ajp and rolling upgrade automatically?

I have 4 Tomcat servers and 1 Apache HTTPD server and run mod_proxy_ajp: <Proxy balancer://cluster> BalancerMember ajp://10.27.1.21:8009 BalancerMember ajp://10.27.1.21:9009 ...
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1answer
47 views

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 ...
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2answers
84 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 ...
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2answers
36 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 ...
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1answer
43 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 ...
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1answer
161 views

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 ...
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37 views

Why Redis Sentinel can't manage 2 master servers?

I'm trying to configure Redis to have a master in each of our two main data centers. But the second Redis master keeps being demoted to slave of the first sentinel array. My version is 3.0.5. In each ...
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2answers
119 views

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 ...
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25 views

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 ...
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1answer
196 views

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 ...
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63 views

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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59 views

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.
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24 views

Scaling and HA LEMP coming from a single server setup

here is the current configuration 1 Server: nginx php-fpm memcached mariadb 10 The project is growing fast and in the midterm we need to scale. When I have to setup multiple machines I want to ...
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22 views

keepalived should vote more relaxed, is raising garp_master_delay and/or advert_int the solution?

Im using keepalived on two machines. The one being the master establishes an ipsec tunnel. Sometimes (once a month or less) the vrrp packet was missed, and the backup takes over, establishes the ipsec ...
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1answer
174 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 ...
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1answer
52 views

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
52 views

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 ...
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1answer
214 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 ...
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1answer
156 views

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 ...
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1answer
22 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 ...
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1answer
20 views

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 ...
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162 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 ...
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1answer
277 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 ...
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165 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 ...
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1answer
131 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 ...
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1answer
38 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. ...
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56 views

Linux Heartbeat error

I'm getting the below error while heartbeat is running. I have checked authkey files and they have the same details on both servers. The hostname is also correct. These 2 servers are also on their own ...
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1answer
68 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 ...
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1answer
52 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 ...
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1answer
35 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 ...
3
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18 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 ...
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1answer
74 views

What is the best practice for deploying dev database to live system?

My developers in a project want to have the dev db on dev server synced with live db on live servers, which I think is a bad idea. Despite that, what is the best way to deploy a codebase+db to live? ...
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1answer
256 views

How to set up an automatic failover reverse proxy for two identical Icecast master servers?

I'm trying to do simple everything double with a reverse proxy in the front high availability for an Icecast master streaming server (i.e. I'm not talking about Icecast relays here). So, three VMs: ...
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1answer
35 views

how to prevent Innob db spiking at 97% Disk I/O Utilization

Our database(InnobDb) is spiking at 99% I/O at random times. After the spike it goes down to about 2% until it spikes agian. There are not some "super" queries that are running in these intervals. We ...
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2answers
104 views

server crashes under high load

We are running a setup that has gotten a lot of media attention these days and we expect the traffic to continue. We have 1 haproxy loadbalancer, 3 application servers(2 image, 1 general) and one ...
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1answer
66 views

2 Node Failover Cluster

I need to build a 2 node Hyper-V failover cluster, that's dead simple right? The problem is that the hardware is already bought. Both servers are identical and approved. Related spec: 250GB Drive ...