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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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 ...
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6answers
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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 ...
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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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7answers
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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 ...
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7answers
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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 ...
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3answers
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The downsides of using nginx as a primary web server?

I've seen millions of websites using nginx as a proxifying webserver working together with Apache. But I've seen very few servers running nginx only as their default webserver. What are the main ...
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8answers
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Load balancing Apache on a budget?

I am trying to get my head around the concept of load balancing to ensure availability and redundancy to keep users happy when things go wrong, rather than load balancing for the sake of offering ...
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7answers
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Avoiding DNS timeouts when a dns server 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 ...
11
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8answers
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Looking for a recommendation on measuring a high availability app that is using a CDN

I work for a Fortune 500 company that struggles with accurately measuring performance and availability for high availability applications (i.e., apps that are up 99.5% with 5 seconds page to page ...
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2answers
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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. ...
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5answers
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what cluster management software to use for linux?

I have found the following cluster management software tools: pacemaker (clusterlabs.org), - original a Heartbeat project, focus for high-availability, will be in the next debian version openqrm ...
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8answers
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High Availability DNS Hosting Strategy?

I'm trying to find a few options of ways to do high availability DNS hosting for a few existing websites. This morning, the company I work for was brought to its knees because the DNS hosting we have ...
9
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5answers
458 views

High server availabilty for a small business

After having a bit of scare with a server that wouldn't come up one morning, the higher ups have decided that the business needs a high availability / fail over setup. We have 5 main servers (4x ...
8
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5answers
671 views

Setup for high availability virtualized environment

For a project I have the task of planning a high availability setup for a web shop and CMS system. However, of course the project is on a tight budget. So a high end solution might not be in the ...
8
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10answers
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good failover / high availability solutions for linux?

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). ...
8
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3answers
781 views

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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2answers
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Avoiding SPOFS with GlusterFS and Windows

We have a GlusterFS cluster we use for our processing function. We want to get Windows integrated into it, but are having some trouble figuring out how to avoid the single-point-of-failure that is a ...
8
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1answer
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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 ...
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3answers
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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 ...
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4answers
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How do sites such as Google achieve high availability? [closed]

As I understand it, when I open a website such as Google, the hostname is looked up and my browser uses the resulting IP address to connect to the server and retrieve the page. However, how do high ...
7
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2answers
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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 ...
7
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4answers
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What exactly does Gluster do?

I've been playing with gluster for the last 2 days and been asking questions here and on their questions system. I really don't understand some of the stuff. I see people saying stuff like Set up ...
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7answers
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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 ...
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3answers
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SQL Server - Cluster vs Mirror for high availability?

I have been doing research into various high availability options for SQL Server 2005. With regard to high availability, what circumstances would favor clustering over mirroring as an option? From ...
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4answers
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Can Exchange 2010 high availability be achieved with only 2 servers?

In Exchange 2010, you can define Database Availability Groups and have your mailbox database(s) automatically replicated between multiple servers, and you can have mailbox server which are members of ...
6
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3answers
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Is Clustering really = High Availability?

These days clustering is becoming synonymous to high availability. As an enterprise architect I have to shake my head in disbelief. IMHO, clustering can be a component of HA but is far from being HA ...
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2answers
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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.
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5answers
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Fault tolerant server structure for the smallest of businesses

I'm trying to figure out what to do for a small business that has been plagued by ridiculous hardware problems. Right now, this business runs on five or six desktop machines; no server infrastructure ...
6
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1answer
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Should an HA failover occur in this scenario?

I'm running vSphere 5 in an HA cluster across two hosts (vsphereA and vsphereB). I have the HA cluster configured for host monitoring and datastore heartbeat monitoring with admission control disabled ...
6
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3answers
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Seeking distributed, fault-tolerant, networked block storage [closed]

I'm looking for a distributed, fault-tolerant network storage system which exposes block devices (not filesystems) on the clients. A client's block device should write simultaneously to several ...
6
votes
3answers
516 views

Apache availability with the two front-ends on diferent locations. Is it possible?

I have to locations (office and service providers). One DNS(bind) serving our domain as authoritative, and a service provider webserver with our corporate web on a private server. So.. Now we are ...
6
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13answers
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Move SQL-Server Database with zero downtime

Is it possible to move a sql server 2005 db to a different server running sql server 2008 without any downtime? The system is 24/7 and has to be moved to a different server with different storage. We ...
6
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1answer
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Does SQL server log shipping require a 2nd SQL license [duplicate]

Possible Duplicate: Can you help me with my software licensing question? I'm currently working on a high availability solution for SQL Server 2008. I have 2 servers with 1 license of ...
6
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1answer
753 views

Why doesn't VMWare DRS automatically migrate VMs when a host is put in maintenance mode?

We have 4 ESXi 5.0 hosts in a VMWare cluster on shared storage (NFS) with DRS and HA on. We want to perform a memory upgrade on one of the hosts. We put that host in maintenance mode but DRS did not ...
6
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3answers
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Is there a way to force heartbeat to add new ip addresses to the system without a full restart?

We utilize heartbeat for High Availability. I'd like to add an additional ip address to the heartbeat cluster, but I don't want to do a full restart of the cluster in the process. Is there a signal ...
6
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2answers
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Can not switch drbd to secondary

I'm running drbd83 with ocfs2 in centos 5 and planning to use packemaker with them. Afer some time, I'm facing drbd split brain problem. version: 8.3.13 (api:88/proto:86-96) GIT-hash: ...
6
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1answer
829 views

What's the best practice for hot-redeployment of WARs to Tomcat?

What's the best practice for hot-redeployment of WARs to Tomcat? Say that I have a webapp that serves a long-running type of user (logs in in the morning, uses all say), and want non-stop redeployment ...
6
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2answers
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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 ...
6
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1answer
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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: ...
6
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1answer
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Stretched datacenter between cities

We're planning to implement a stretched datacenter between our two sites. The connectivity between them is a single 100mbit QinQ connection. We have about 500 users at site A and 200 users at site B. ...
5
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4answers
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Ganeti vs Proxmox [closed]

I'm system administrator in small software house. I'm going to virtualise our servers. The main reason for doing this is providing highest possible uptime, but probably it will also increase resources ...
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3answers
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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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4answers
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Can SQLite be used with GlusterFS?

I want to build a distributed storage based on GlusterFS with Automatic File Replication (AFR) to store users files in a fault-tolerant way. But I also want to access an SQLite3 database stored on ...
5
votes
1answer
443 views

VMware vSphere DRS affinity rules for more than 2 guests

I've received a request to add disaffinity/anti-affinity rules on a set of virtual machines in a VMware HA/DRS cluster running VMware vSphere 4.1. The client has four hosts and wants to keep certain ...
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4answers
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SonicWall “gotchas”?

We're looking to move away from PFSense and CARP to a pair of SonicWall NSA 24001 configured in Active/Passive for High Availability. I've never dealt with SonicWall before, so is there anything I ...
5
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2answers
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High-availability on SQL Server, cons and pros of solutions?

I'm studying about high-availability on SQL Server for my thesis. I've learned there're several solutions to archive this: Failover clustering Log shipping Replication As I know, these solutions ...
5
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3answers
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How can I load-balance a load balancer?

I'm about to convert a single-server single-database web application into a physically distributed high-available configuration with servers on two physical locations (for now). Now, obviously, I need ...
5
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2answers
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Is this a reasonable architecture for a newspaper site?

We run a newspaper-style site and are consolidating our architecture from one that grew amorphously into a more scalable, resiliant solution. I was thinking of the following: internet | h/w ...
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4answers
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Providing high availability and failover using MySQL on EC2

I would like to have a highly-available MySQL system, with automatic failover, running on Amazon EC2 instances. The standard approach to solving this is problem Heartbeat + DRBD, but I've found a lot ...
5
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2answers
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How stable is the VMWare vCenter Server OVF and is there a better way to get HA features?

I am considering pruchasing Vsphere solely for the HA feature, however, in order to do this, I will also need vCenter Server. I am not keen on purchasing a copy of Windows especially for this and ...