Redundancy is the duplication of critical components or functions of a system with the intention of increasing reliability of the system, usually in the case of a backup or fail-safe.

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Automatic WAN failover

My workplace has two WAN links, one of which we use as a backup. Both links terminate as Cat5. Unfortunately, we've had bad luck with "dual-WAN" routers, so our current failover plan is to unplug our ...
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3answers
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Recommendation for a small redundant VM infrastructure?

We currently have an active-active 2 node cluster running virtual machines. Every node has two disks, every disk is DRBD mirrored on the other node. Every node runs virtual machines out of his primary ...
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2answers
331 views

We need MySQL redundancy but replication is not an option

We have an app with some peculiar characteristics that prevent us from doing master-slave MySQL replication. It's something to do with random numbers being generated for each session and stored ...
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3answers
1k views

Redundant DNS setup

I have a problem with my DNS setup and I really can't understand what's wrong with it. We host our own public DNS servers on 2 different networks (technically, we have 3 DNS servers on 3 different ...
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2answers
464 views

DNS setup for website on geo redundant servers

Let's say: I have a website written in English and shown on www.example.com. The website is on a US server now (based on cPanel/WHM) at the IP address 192.0.2.0. I can manage the DNS of example.com ...
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1answer
64 views

Mobile broadband Server backup

We have a windows server. It is attached to a UPS. The internet connection is not plugged into the UPS. If the power goes down in the building the UPS kicks in and emails out saying that the UPS is ...
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3answers
233 views

New to RAID and redundancy

I just purchased an HP Proliant DL580 G2 server. I have never used RAID, but this system comes with: Smart Array 5i Plus Controller (integrated on system board), Dual Channel, Ultra3 (supports RAID ...
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4answers
907 views

Are Dell R610 4 Port NICs as good as a Second NIC in terms for Redundancy

So my general question is does a multiple port NIC supply the same redundancy that two complete NICs do? My Specific question is in what is the case with the 4 port NIC that comes in Dell R610s. I ...
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4answers
329 views

is it possible to use a windows server as a datastore for vmware esx server

I'm a relative noob at virtualisation but would like to roll it out in our organisation. The application I'd like to test with needs to be back up pretty quickly after failure... So I'd like to put 2 ...
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2answers
111 views

need scalable, highly available transactional log server

My requirements: 1) must be able to continue operating after node failure 2) logs must be recoverable after node failure - no data loss 3) must be able to scale out 4) must be transactional - when a ...
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3answers
1k views

Aggregate multiple WAN connections (DSL, WiFi, WiMax) with a static IP, without BGP

Is it possible to use two VPN or MLPPP routers to aggregate, load balance, or fail over between WAN connections from a number of different providers? Two conditions: 1. We need to keep the external ...
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2answers
535 views

HAProxy to the rescue? (multiple machines w. vhosts)

This is more of a 'best practice' or 'input appreciated' question. Currently we manage about 5 webservers (in two DC's) that run Nginx for PHP websites. The plan is to redesign the setup so it is ...
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3answers
287 views

Can I use two different servers for one site? how?

Is it possible to use two servers (or more) for the same site, and with different data? For example server1 has page1.html, and server2 has page2.html and they both can be accessed from www.site.com. ...
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1answer
898 views

Using a Dell PowerConnect to set up load balancing/redundancy, 1 switch 2 routres 2 private wan links

We have different locations connected by two different WAN providers. Each site has a dell powerConnect 6224 and two cisco routers with the WAN connections (we don’t have access to router admin). The ...
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2answers
3k views

How to achieve redundancy across data centers?

I have a LAMP server with a lot of hardware redundancy built in. I am not worried about the server becoming unavailable. What I am worried about, however, are potential network issues in the data ...
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3answers
104 views

Back-end SQL Server 2005 databases for website

We're migrating an existing IIS website + MS SQL 2005 database (on the same server) to a new test set-up. The existing set-up is too slow. I want one ISS server and 2 X MS SQL server 2005. One live ...
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3answers
470 views

Is it possible to guarantee 100% uptime in redundant hosting servers inside a cloud computing structure?

I'm interested in find a hosting that can offer really 100% of uptime. Is it possible in hosting servers inside a cloud computing structure?
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2answers
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Recommendation for a redundant 60V DC Powersupply

We have some Telco-Equipment in our data space center which we had been given by our Telco. What they didn't provide is a redundant power supply and therefore we are struggling with outages of this ...
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4answers
2k views

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 ...
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1answer
273 views

Simplicity vs Redundancy

Assume you are tasked with running a set of mission critical web services with a targeted up time of 99.5% To achieve this, you have two identical clusters of hardware in two entirely separate data ...
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2answers
231 views

How common is it to use additional dedicated servers for redundancy?

I'm new to handling the infrastructure for production service deployments. My intuition tells me that if I want to have my service be "up" as much as possible and yet can only afford say 2 dedicated ...
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2answers
1k views

cPanel web server redundancy advice?

At present I operate a (reasonably low volume) web-hosting service with a Centos 5.3 server running cPanel/WHM. I would like to implement a level of redundancy such that in the event of server ...
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1answer
877 views

Reverse Proxy failover scenarios?

I currently have 2 apache web-servers that run ldirectord/heartbeat to load balance between them. Whenever I reboot one of the web-servers, or take it down for maintenance, ldirectord automatically ...
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1answer
1k views

EIGRP for Failover

Preface: Reading through O'Reilly's Network Warrior in the chapter "Ethernet Resiliency he describes the following Scenario (Trying to keep this in the limits of fair use): "Assume that the link ...
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2answers
463 views

IIS replication - Is it possible

I have a requirement for a client that I have a centralised system that all his satellite branches can work on. Currently this is a ASP.net web forms app running under IIS 7 on win 2008 RC 2 using an ...
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2answers
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Network Redundancy Example

Looking for help filling in how redundancy in the following model might work: I believe my Datacenter will give me redundant gateways with two hand offs (going to have to talk to the more about ...
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3answers
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Redundant links from Router to Switches

With a setup of two NICs on a server into two different switches where each NIC has a different IP (But both on the same network), and then the switches to the router. How would I configure the two ...
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3answers
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Getting Started with NIC and Switch Redundancy

Currently with my servers, they all or almost all have 2 nics with one in use. Each NIC is is of course connected to a single switch. What do I need to do to make this redundant in that both NICs ...
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1answer
260 views

Plug single PSU into two different power sources

We have a rather uncommon situation: We have a server in a computer center. Its got not enough spare space to put in a redundant PSU. Nevertheless, we want to attach the single PSU to both existing ...
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2answers
280 views

Server Redundancy

I have web hosts at 3 different locations. I want to create a fail-safe for the websites, so if one host is down, the web sites are still available.
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3answers
154 views

Windows Home Server style redundancy/multi-disk-support on Windows Server 2008 R2?

I'm setting up a fileserver for our department. It'll be connected to the domain. I want it to have a very large amount of storage (several TB). Ideally, it should also preserve disk space by ...
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16answers
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Is Round-Robin DNS “good enough” for load balancing static content?

We have a set of shared, static content that we serve up between our websites at http://sstatic.net. Unfortunately, this content is not currently load balanced at all -- it's served from a single ...
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1answer
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Ideal redundancy configuration for 3 physical servers running IIS and SQL Server

I'm looking to set up as redundant an architecture as possible to serve a data-centric web application with only 3 servers (only 5U of rack space). Between these two setups, which would be most ideal, ...
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762 views

Redundant network connections for website

We are in the process of building a new secure web application for our company, and are looking at options for ensuring redundancy in our data center. We don't have a lot of money, but have ...
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8answers
951 views

Which is more standard in large enterprises: RAID5 or RAID10?

Which is more standard in large enterprises: RAID5 or RAID10?
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158 views

External Network Drive for Backup

My problem is that I have a server class machine with mission critical data sitting in a building and I have no data redundancy outside of the building. What's the cheapest solution to backup the ...
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2answers
441 views

tools for geographical redundancy

I'm writing a spec for a high availability application. I need a low budget solution to be able to failover between two data centers. Replicating databases and content I'll be able to manage solutions ...
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2answers
489 views

Best method to get “transparent” redundancy for Ethernet?

My apologies if this is an obvious question, I'm a newbie as far as redundant networking goes, and I'm not sure what keywords to Google for. My application scenario is this: The system consists of ...
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2answers
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RAID5 and persistent write-intent bitmaps

I have a Ubuntu 8.10 software RAID5 setup that uses 4 active disks and 1 spare. The spare disk has three partitions, one of which is devoted to the spare function. I am using a second partition on ...
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3answers
759 views

Sharepoint - one way sync to a second SP server for standby/backup

Using MOSS 2007 on SQL server 2005 is there any way to do a "one-way" synch of data from a production server to a standby server? This would be a one-way process only, and can happen daily rather ...
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1answer
135 views

Adding a second line to a domain

I'm running a Windows 2003 single domain network. We currently have a single connection line run in to an inbound nic in our ISA firewall. Outbound nic goes to a switch and from there to all other ...
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2answers
381 views

Can you recommend a failover solution for setups running multiple VPSes?

Here's what I have to work with: Root access to VPSes with different hosting companies that run CentOS only Two dedicated nameservers with over 100 zone entries Several webservers hosting the same ...
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3answers
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Linux console is unusable when LDAP server is down

When our OpenLDAP server lost power the CentOS machines' console became nearly unusable. We were trying to login with a local account, but each command would take minutes to return. Even simple ...
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11answers
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How far should we take the N+N redundancy craziness?

The industry standard when it comes from redundancy is quite high, to say the least. To illustrate my point, here is my current setup (I'm running a financial service). Each server has a RAID array ...
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9answers
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Correct way to set up DNS primary/secondary/… for redundancy and latency reduction?

I thought DNS primary/secondary for redundancy purposes was straightforward. My understanding is that you should have a primary and at least one secondary, and that you should set up your secondary in ...
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6answers
772 views

Server Failover Scenario

I've got two Dell PowerEdge 2950 servers. In order to (hopefully) eliminate any downtime, I must implement a solution to detect and adjust to component failures, environment failures, etc ... the ...
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4answers
11k views

Split your DHCP scope among multiple servers?

I want to implement a redundancy solution. I have two subnets all windows XP machines - each with their own DHCP server - joined by a bridge. Currently - all machines get DHCP leases from the one ...
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5answers
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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 ...
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5answers
663 views

Self-healing archive file format with redundancy

When I used RAR, I had an option to add some extra recovery data in order to be able to cope with a not-perfect medium (think floppy disks). It saved my day several times, specially when dealing with ...
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When is RAID worth the trouble?

In our shop we're faithfully using RAID in all our workstations, probably just because that seems to be the way it ought to be done. I'm talking about workstations for scientific simulations, using ...