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 ...

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102
votes
15answers
81k views

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 ...
4
votes
5answers
5k views

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 ...
235
votes
27answers
56k views

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 ...
5
votes
2answers
3k views

How browsers handle multiple IPs

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 ...
5
votes
2answers
8k views

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 ...
3
votes
2answers
2k views

Keepalived over GRE tunnel for failover on VPS environment

I'm running an application on Linode. Their network does not support multicasting. Many tools used for failover (keepalived, spread/wackamole, hearbeat) require multicast to work (as far as I know). ...
7
votes
7answers
3k views

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 ...
4
votes
9answers
12k views

Best solution for Multi-WAN failover (inside & out)? [closed]

Looking for a way to setup 2 ISPs in failover mode, for both incoming & outgoing traffic, for our small (<100 devices) network. The leading contender for now seems to be the Peplink Balance ...
3
votes
4answers
2k views

Apache Failover and Load Balancing

I am working for a small finance firm as a Web Application Developer. Our company has an interal website coded in PHP and running on Apache. Recently our server went down and the website was down for ...
5
votes
3answers
3k views

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 ...
4
votes
2answers
4k views

NIC Active/Passive bonding with priority

I will configure a bond of three NIC's. I want to define which one will be first used and which NIC will be used as the second and third NIC when failover is done. Is this possible? Thanks
2
votes
1answer
2k views

relation between heartbeat,openais,corosync

i am planning for high availability on lucid ubuntu, i started with drbd after a simple configuration on drbd I went to heartbeat and had a simple config on it too. on drbd official site a document ...
2
votes
2answers
474 views

Azure Load balancing internal instances of web/worker roles?

As far as I know Azure does not have a load balancer for internal services, internal endpoints are not load balanced. But can someone have implemented a "soft" solution, or can advice me some helpful ...
1
vote
1answer
220 views

How could dynamic DNS work if DNS updates take hours to propagate?

Simple Failover markets itself as: continuously monitors your servers to find out which are up and which are down, and then it dynamically updates your DNS records accordingly so that your ...
1
vote
1answer
613 views

“Simple” Failover to a Geographically Separated Server?

I've been reading about DNS failovers and a bunch of other technical terms however I'm a bit of a newbie in this so it all sounds Greek to me. Basically here's what I just need: I have two shared ...
1
vote
1answer
2k views

iSCSI / SAN / Cluster / multiple NICs failover problem

Got a problem with NIC failover with iSCSI. Setup: A server with 3 NICs. One NIC is local network, other 2 are SAN. Using Microsoft iSCSI Initiator. A managed network switch. A QNAP SAN, connected ...
24
votes
15answers
18k views

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 ...
2
votes
9answers
6k views

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 ...
1
vote
3answers
4k views

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 ...
15
votes
5answers
1k views

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 ...
7
votes
2answers
585 views

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 ...
3
votes
2answers
2k views

Redis Master and Slave usage

While I know how to configure and run Redis master and slave on two different servers, I would like to whether my Webserver will be able to connect to slave redis server if the master redis server ...
1
vote
2answers
4k views

How to configure failover for JBoss AS 5?

I am currently an intern in my company. My boss basically wants me to perform a failover from a JBoss AS to another just for a proof of concept. Load balancing is not required as i am only required to ...
6
votes
6answers
10k views

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). ...
5
votes
1answer
2k views

DNS Round-robin failover and load balancing

Having read all of the questions and answers (1 2 3 and so on) on here relating to DNS load balancing, and Round-robin DNS, there's still a number of unanswered questions.. Large companies, and I'm ...
3
votes
4answers
5k views

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 ...
2
votes
1answer
4k views

How to make iptables ALLOW rule for multicast?

I have two servers that uses ucarp as failover. On each server eth1:1 is reserved for ucarp's keepalive connection. ucarp uses the destination IP as multicast address 224.0.0.18. On ucarp master ...
2
votes
2answers
2k views

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 ...
1
vote
1answer
368 views

DC/DNS failover with global/common DNS roundrobin

I think I am getting lost in network failover land. I am trying to set up a Windows Domain Controller and DNS, while providing resilients and failover. I have two Domain Controllers and DNS servers. ...
3
votes
1answer
1k views

Heartbeat Pacemaker 3 node/ip failover

I have setup two node active/active ip failover with heartbeat and pacemaker following the link at zivtech on the two load balancers for the backend web servers. Two LBs has public ip each which is ...
3
votes
3answers
782 views

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 ...
3
votes
6answers
2k views

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 ...
2
votes
3answers
2k views

Using a low TTL to help prevent extended periods of downtime

Is it feasible to set my domain's TTL to a very low value (a couple of minutes) so that, if my main host goes down for an extended period of time, I can update the DNS records in my main host to point ...
2
votes
1answer
422 views

Intermittent unavailability of an instance in a failover cluster while a standby node is offline in a SQL Server 2008 failover cluster

I've got a small failover cluster that I run for the websites my company has. During a RAM upgrade of the standby server, our websites started to show errors about not being able to access the ...
1
vote
1answer
558 views

Best failover strategy for e-mail servers on AWS to ensure high availability

We have our e-mail server hosted on AWS. Last week Amazon had a failure in their East Coast region which brought down our server along with many others. We now want to implement a failover strategy ...
1
vote
2answers
372 views

SSD redundancy via HDD

Is there a way to guarantee redundancy to an SSD using an HDD? Raid 1 is the best choice to guarantee redundancy in HDDs, but SSDs are too expensive to guarantee redundancy via RAID. If I was to ...
1
vote
3answers
521 views

Firewall or other solution for automatic fail-over to a second server?

Assume a situation like this: Server 1 - FreeBSD, Apache -- serves all web traffic Server 2 - FreeBSD, Apache -- just sits there idling Is that an easy way to set things up so that if Server 1 ...
1
vote
2answers
2k views

Failover between 2 catalyst 2960s

We have two catalyst 2960s and four linux servers that we would like to connect to both switches (each server having one link to each switch.) Ideally, we are looking for seamless failover in case a ...
0
votes
1answer
187 views

Cisco ASA failover can't ping gateway

I'm currently trying to set up a failover network for my Cisco ASA 55x0 using the SLA traking. I have the "outside" interface (network 89.x.x.48/29) and the "outside2" interface (network ...
0
votes
3answers
278 views

Manage DNS outage

I have been using ZoneEdit to manage my DNS. This has been generally fine except I did have a half our outage where two of their DNS servers were down causing my site to be inaccessible. What is the ...
0
votes
1answer
285 views

redirect to a static page on another web server when main web server is down

We have a single IIS web server in house that when it goes down we would like to redirect traffic to another web server and display a message that the web site is down. I have been all over the net ...
0
votes
4answers
411 views

Datacenter power failure failover

We recently had our datacenter's power go. We are protected by an SLA and use DNS to redirect users when a failure is detected. DNS isn't designed to do this by design. Is this the most practical way ...
0
votes
6answers
4k views

Low-cost ISP failover for inbound traffic?

We host one web server on our office internet connection (cheap!). The DNS servers are external and not provided by the ISP. When the connection goes down we would like to have a backup solution. The ...