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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.

High availability is an architectural consideration often involving degrees of redundancy to insure availability in case of system or component failure. Highly available systems are commonly implemented in situations where the risk outweighs the cost.

Best practices such as change control, standardized procedures, and monitoring can also enable high availability.

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Multiple data centers and HTTP traffic: DNS Round Robin is the ONLY way to assure instant fail-over?

Multiple A records pointing to the same domain seem to be used almost exclusively to implement DNS Round Robin as a cheap load balancing technique. The usual warning against DNS RR is that it is not good for high availability. When 1 IP goes down…
Valentino Miazzo
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Windows 2008 ignores Gratuitous ARP requests

We recently saw an issue after a fail over of our router where our Windows 2008 Boxes didn't start talking to the primary router after fail-back. When we did some digging they still had the ARP entry from the secondary router. According to the…
Zypher
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Alternatives to Heartbeat, Pacemaker and CoroSync?

Are there any major alternatives for automatic failover on Linux besides the typical Heartbeat/Pacemaker/CoroSync combinations? In particular, I'm setting up failover on EC2 instances, which only supports unicast - no multicast or broadcast. I'm…
organicveggie
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Avoiding DNS timeouts when a DNSserver fails

We have a small datacenter with about a hundred hosts pointing to 3 internal DNS servers (bind 9). Our problem comes when one of the internal DNS servers becomes unavailable. At that point all the clients that point to that server start performing…
Neil Katin
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What is the difference between keepalive and heartbeat?

I want to structure a high available server cluster . Now I want to know detail about keepalive and heartbeat, what is the difference between both, and How to choice one.
aboutstudy
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What is the difference between Anycast and GeoDNS / GeoIP wrt HA?

Based on the Wikipedia description of Anycast, it includes both the distribution of a domain-name-to-many-IP-mapping across many DNS servers as well as replying to clients with the most geographically close (or fastest) server. In the context of a…
Riyad Kalla
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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 time for no reason? If the majority current…
HiPerFreak
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Highly-available, Web-accessible and scalable deployment of statsd and graphite

I'd like to setup statsd/graphite so that I can log JS apps running on HTML devices (ie. not in a contained LAN environment, and possibly with a large volume of incoming data that I don't directly control). My constraints: entry point must speak…
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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-hour power outage that knocked us completely…
Mike
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When is the right time to introduce high availability for web site?

When is the right time to introduce high availability for web site? There are many articles on High Availability options. It’s not that obvious however WHEN is the right time to switch from single server to high availability configuration. Please…
Dennis Gorelik
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Options for Multisite High Availability with Puppet

I maintain two datacenters, and as more of our important infrastructure starts to get controlled via puppet, it is important the the puppet master work at the second site should our primary site fail. Even better would be to have a sort of active /…
Kyle Brandt
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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 out how to get it to work unless both web servers…
David Cary
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Replicating beanstalkd for High Availability

Title says it all. Does anyone know of a way to replicate beanstalkd such that if a beanstalk server went down, others slaves could take over? Here's one approach I thought of: I could make beanstalk write its binlog (with the -b) to a shared…
Josh Nankin
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How to do client side NFS failover in Linux?

I have a CentOS 6.3 client that needs to access NFS storage. There are two NFS servers that serve up the same content stored on a SAN with a clustered filesystem. How do I set up CentOS to failover to the backup NFS server if needed? When I…
Doug
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How to setup STONITH in a 2-node active/passive linux HA pacemaker cluster?

I am trying to setup an active/passive (2 nodes) Linux-HA cluster with corosync and pacemaker to hold a PostgreSQL-Database up and running. It works via DRBD and a service-ip. If node1 fails, node2 should take over. The same if PG runs on node2 and…
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