Questions tagged [failover]
In computing, failover is automatic switching to a redundant or standby computer server, system, or network upon the failure or abnormal termination of the previously active application, server, system, or network. Failover and switchover are essentially the same operation, except that failover is automatic and usually operates without warning, while switchover requires human intervention.
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100% uptime for a web application
We received an interesting "requirement" from a client today.
They want 100% uptime with off-site failover on a web application. From our web application's viewpoint, this isn't an issue. It was ...
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Why is DNS failover not recommended?
From reading, it seems like DNS failover is not recommended just because DNS wasn't designed for it. But if you have two webservers on different subnets hosting redundant content, what other methods ...
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nginx automatic failover load balancing
I'm using nginx and NginxHttpUpstreamModule for loadbalancing. My config is very simple:
upstream lb {
server 127.0.0.1:8081;
server 127.0.0.1:8082;
}
server {
listen 89;
...
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2
answers
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nginx reverse proxy - try upstream A, then B, then A again
I'm trying to set up nginx as a reverse proxy, with a large number of backend servers. I'd like to start up the backends on-demand (on the first request that comes in), so I have a control process (...
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Cheapest iSCSI SAN for Windows 2008/SQL Server clustering?
Are there any production-quality iSCSI SANs suitable for use with Windows Server 2008/SQL Server for failover clustering?
So far, I've only seen Dell's MD3000i, and HP's MSA 2000 (2012i), which both ...
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2
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LVS vs HAProxy, which should I choose?
I am looking for a solution to load balancing and failover strategy, mainly for big web applications. We have many services to be balanced, such as web, MySQL, and many other HTTP or TCP based ...
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6
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DNS Round Robin: Do browsers stick to one IP as long as it is online?
How do most browsers behave if they get multiple A-records from the DNS server? Do the stick to one IP as long as it is reachable (and only use another if the IP is down)? Or do they switch all the ...
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nginx failover without load balancing
I'm having trouble configuring nginx.
I'm using nignx as a reverse proxy. I want to send my all requests to my first server. If the first server is down, I want to send requests to second server.
In ...
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17
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2
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What happens when a load balancer fails?
Let's say I'm using Amazon's EC2 load balancer. I have it hooked up to two instances (excuse me if my terminology isn't correct). What happens if the load balancer fails? Do both instances fail to ...
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How to setup HAProxy with failover?
I understand that, to get failover on an HAProxy load balancing setup, you need two machines running HAproxy (and route it to several webserver instances). But in this case, say abcd.com, how do we ...
- 383
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Multi-site high availability
We have a SaaS application that we need to be highly available. We already have an expensive, well-maintained Hyper-V failover cluster, but today the datacenter where we host that cluster had a five-...
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When my A web server gets unplugged, how do I automatically redirect all the users to my B web server in another city, and vice versa?
When my A web server gets unplugged, how do I automatically redirect all the users to my B web server in another city, and vice versa?
A load-balancing switch does what I want, except I can't figure ...
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4
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Link bonding across multiple switches?
I've read up a little bit on bonding nics with ifenslave; what I'm having trouble understanding is whether there is special configuration needed in order to split the bonds across two switches. For ...
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How browsers handle multiple IPs [closed]
Can someone direct me to information on exact browsers behavior when browser gets multiple A records for a given hostname (say ip1 and ip2), and one of them is not accessible.
I interested in EXACT ...
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How do you automate failover on EC2?
Of the folks managing their own clusters (i.e. not using/paying for Amazon Autoscale, Rightscale, Scalr, etc.), how are you managing your instances on EC2 and handling (e.g.) failover? I'm wondering ...
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Why are my HyperV VM's randomly losing connectivity?
I have a strange intermittent connectivity problem happening about once every two weeks.
First my configuration: I am running a HyperV failover cluster with two physical hosts (node01 and node02). ...
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2
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nginx use proxy cache if backend is down
I need to nginx proxy use cache if backend server down:
this is my configuration. but seems be nginx use cache without check backend server.
http {
# ...
proxy_set_header Host $host;
...
10
votes
2
answers
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Server 2016 MSMQ failover
I would like to setup a MSMQ in a failover system.
I do not have a shared storage setup (hardware not available - budget),
but i have three dl380 running windows server 2016.
I would like to setup ...
- 202
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votes
1
answer
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Keepalived send gratuitous ARP periodically
Is there a way for a keepalived to send gratuitous ARP periodically?
We had following situation:
switch failure (VLAN setup)
keepalived failovered to backup instance
backup instance sent gratuitous ...
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11
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good failover / high availability solutions for linux? [closed]
I have several cases where I need applications to be migrated from one server to another in the event of a failure (server hang or crash).
On solaris we do this with VCS (Veritas Cluster Server).
...
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3
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Global high availability setup question
I own and operate visualwebsiteoptimizer.com/. The app provides a code snippet which my customers insert in their websites to track certain metrics. Since the code snippet is external JavaScript (at ...
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Hot spare host vs cold spare host?
We have several hosts where we have an identical hot spare host, which is patched and updated so it is very close to have to same software and config. In case of failure the network cable is switched ...
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Access files located on the underlying filesystem of an NFS mountpoint
Perhaps this is an odd request, but it's the opposite of the question detailed at:
Is it possible to view the contents of an underlying NFS mount without unmounting the NFS content?
I have an ...
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2
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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 ...
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How to perform cron jobs failover?
Using two Debian servers, I need to setup a strong failover environment for cron jobs that can be only called on one server at a time.
Moving a file in /etc/cron.d should do the trick, but is there ...
- 1,722
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votes
6
answers
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Ubuntu failover from Ethernet-to-ADSL-modem to USB 3G dongle
I have an internet connected Ubuntu server, connected by Ethernet to a residential ADSL line. This is adequate, most of the time, but I can't rely upon the ADSL link to be as reliable as I'd like. ...
- 231
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votes
1
answer
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Azure Site Recovery unplanned failover
I have managed to create a DR of a couple virtual machines to Azure. I am using Azure site recovery and Azure resource manager, and I followed this manual about how to do this https://www....
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2
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Redis high availability and load balancing
I'm using Redis for some time and now we want to move to a redundant cluster which would be fault tolerant, highly available and load balanced.
I principally use Redis for some PHP web application ...
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A-Record Failover?
I have a Fortigate 100D with 2x BT Business Infinity Fibre connections acting as WAN1 & WAN2.
The BT lines come with 5 static public IPs each and I have my DNS hosted through CloudFlare pointing ...
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Is it possible to make redundancy on HAProxy server?
I am going to use HAProxy as a load balancer that will balance requests on 3 application servers. But what if balancer server (HAProxy) fails at some point? I was thinking of cloning the first ...
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If DNS Failover is not recommended, what is?
As a followup question to his very popular question: Why is DNS failover not recommended?, I think it was agreed that DNS failover is not 100% reliable due to caching.
However the highest voted ...
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Linux equivalent of pfsync+carp for failover firewall/routing
I'm currently using a linux box to handle my firewall/NAT using iptables. It has two NICs, one link to a LAN switch, one to our egress Internet provider. I'm looking at upgrade this box to two boxes ...
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Magento hosting on a budget
I have to do a setup for Magento. My constraint is primarily ease of setup and fault tolerance/fail over. Furthermore costs are an issue. I have three identical physical servers to get the job done. ...
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How can I automaticaly change the DNS A record to point my site to a secondary server in case of a failure?
My hosting is charging me a $50/month fee to put my servers on the same VLAN so that I create a cluster using the Network Load Balancing feature.
I'm really not needing split the load between the ...
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PG pool failover leads to two independent masters with network failure
I've got two servers set up with PG Pool to create a HA setup for a webapp.
PGPool and postgres run on both servers, using streaming replication from server 1 to server 2. The webapp on each machine ...
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1
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DRBD for HA Server in Small Office Questions
Backround: We are in need of a HA server in a small office environment and are looking at DRBD to provide it. We only have about 100GB that needs to be on the HA server and server load will be ...
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6
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Cluster failover and strange gratuitous arp behavior
I am experiencing a strange Windows 2008R2 cluster related issue that is bothering me. I feel that I have come close as to what the issue is, but still don't fully understand what is happening.
I ...
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votes
1
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Internal storage as HA failover cluster storage pool ?
I have 2 HyperV server (2012 R2) nodes with shared ISCSI storage (ubuntu 16.04) in a Failover Cluster.
I want to make that 3 servers (windows server 2016 and/or 2012r2) each with 2 partitions, one ...
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Browser-based DNS failover using multiple A records
It has recently come to my attention that setting up multiple A records for a hostname can be used not only for round-robin load-balancing but also for automatic failover.
So I tried testing it:
I ...
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Local to Remote Webserver Failover
Short and sweet, I don't suppose you'll need more detail than this:
We host our website on an in-house
webserver.
A catastrophe has and will happen
again where communication from the
web into/out ...
7
votes
1
answer
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MySQL: Pacemaker cannot start the failed master as a new slave?
pacemaker-1.0.12-1
corosync-1.2.7-1.1
I'm going to setup failover for MySQL replication (1 master and 1 slave)
follow this guide:
https://github.com/jayjanssen/Percona-Pacemaker-Resource-Agents/blob/...
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What is the most effective way to setup a linux web server for manual failover
I currently administer a small web server running ubuntu linux with apache, mysql, and ssh.
I'm backing it up using rsync to another server, but I'm backing it up to a /backup directory.
I'd like to ...
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2
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How to create a high-availability application server?
I am working with some hardware units which uses mobile Internet to communicate to my application server.
Initially, the hardware had a hard-coded IP address (load balancer) in the hardware for ...
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How to setup redundancy for AWS Elastic Load Balancers?
In the spirit of redundancy and fail-over, I would like to know some strategies on setting up AWS Elastic Load Balancers for DR, that is, if this is really an issue? (A single ELB would LB traffic to ...
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How do I set up failover for a single web server using two ISPs?
I have one web server and two WAN connections (1 cable, 1 DSL). DNS is run offsite, and points to the IP address assigned by one of the ISPs. How can I have the second connection take over when the ...
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Synology HA active-passive performance and failover
I have two Synology boxes (DiskStation DS1817+) that are running in Synology HA mode filled with WD Black 4TB drives in RAID10. They are connected to my cluster over iSCSI providing mainly backup ...
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How good is failover of the iSCSI target on a two-node linux san?
I'm evaluating the possibility to use two off the shelf servers to build a cheap iSCSI redundant SAN. The idea is to run linux, pacemaker, and an iSCSI target - something like the SAN Active-Passive ...
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Multiple LDAP servers with mod_authn_alias: failover not working when the first LDAP is down?
I've been trying to setup redundant LDAP servers with Apache 2.2.3.
/etc/httpd/conf.d/authn_alias.conf
<AuthnProviderAlias ldap master>
AuthLDAPURL ldap://192.168.5.148:389/dc=domain,dc=...
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Is it possible to merge multiple internet connections?
I have two internet connections at my place but the faster one is actually unreliable. :(
One is a broadband modem connected to PC via ethernet. The other one is a USB modem.
I would want to run ...
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4
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ISC DHCP+BIND with failover and dynamic updates, can the secondary bind update DDNS?
I'm setting up a failover system for DHCP and DDNS. The software being used are ISC BIND and ISC DHCP, running on Ubuntu 10.04 LTS.
serverA runs DNS01 and DHCP01, serverB runs DNS02 and DHCP02. DHCP ...
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