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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Howto create redundant network on server

I am in the situation where I have a number of CentOS Linux servers which all have two NIC interfaces. Currently one of these interfaces is used for internal communication, the other is used for ...
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3answers
578 views

IRC Services with failover support?

I run a single server (call it 'server A') IRC 'network', and thank to the generosity of some friends, I have been given a second server ('server B') that I can run an IRCd on in order to provide ...
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4answers
246 views

Question regarding uptime strategy for website

I'm working on a website where we need to have a good deal of uptime. Specially in the short bursts (15-day periods) that the website's events happen. The page is dead simple and can be served ...
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2answers
156 views

Redunt link over single cisco router

I have one cisco router 3825 with multiple WAN card connected to two ISPs and I have one 2811 with two WAN cards in branch offices. I need to configure these routers to connect both links and once one ...
4
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2answers
446 views

Two domain controllers - yet when primary is down, domain still fails?

I have multiple windows 2003 servers support a particular network, and when one particular server is taken offline, domain services begin to rapidly fail, such as users couldn't login. What check ...
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2answers
3k views

One server, Two APC UPS on redundant power supplies : How to trigger shutdown?

I have a server racked and its redundant power supplies plugged in two APC Smart-UPS 3000 XLM. Each UPS is connected to two different mains power sources. Two instances of apcupsd are running, each ...
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4answers
370 views

System Monitoring Redundancy

I consult in a small business environment where I have two HyperV hosts (with <10 VMs) + a couple other servers. I recently had an issue where one of the HyperV hosts had a CPU issue and it came ...
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2answers
1k views

Can I get redundancy with a JBOD storage subsystem

I have a Promise Technology J610S. This is a JBOD subsystem. Is it possible for me to buy a SAS hardware RAID controller and provide some type of redundancy for these drives? I am unsure whether I ...
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1answer
186 views

Simple Central Storage for HA mail server

I will have 2 Postfix servers. One will be a backup of the other. What is the easiest method to provide central storage to both of these boxes? My infrastructure is very simple: Just a lot of Xen ...
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5answers
2k views

Eliminate single point of failure for webservers?

I know in DNS, that each of the DNS servers will be tried to see if they will respond I know in email that in the event of a failure it will go to the next one in the list or it will hold the mail ...
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3answers
3k views

How to make two UPS redundant?

How to setup UPS for redundant power supply if 1st UPS goes down then system should work on 2nd UPS if 2nd goes down then system should work with 1st UPS like server power supply.
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3answers
482 views

Distributed redundant storage solution?

Is there a way to use extra space on computers as a distributed backup system? I'm thinking that using the extra space on the systems in my network would add a lot of storage to the available pool, ...
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4answers
554 views

Importance of Redundant Power Supply

How important are redundant power supplies in servers, not measured by how critical server uptime is, but by likelihood of failure? In other words, are server PSU's error prone and/or likely to fail ...
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1answer
186 views

Consistent Reliable Messaging

Hay All.. Im working a new project, Im currently deciding between flume & scribe for messaging systems... ( most probably sent to logs or hadoop ) I cannot lose a message ever.. What are ...
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2answers
737 views

redundant network handling in linux box

I need your help very badly. I have give a solution for the requirement. I'm struggling for 5 days to get one. Requirement is to get a solution for redundant network in Linux systems. We have ...
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1answer
373 views

distributed resilient storage system using existing linux spare disk space

tall order this request but I am hopeful... I have a bunch of servers (exactly 20) that each have about 2-7TB of free space, and that space is not in any danger of being used up soon. I was wondering ...
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2answers
55 views

mysql redundancy with mixed storage types

Looking at building redundancy into our system, as we are currently, um, exposed should anything blow up. We have a large-ish DB (150G), consisting of a mix of innoDB and myISAM table types. We want ...
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2answers
132 views

What to do if the failover fails?

I am looking to setup a failover in the following configuration - Failover Server (Frontend) Primary Server - Secondary Server (used if primary server fails) (Backend) So traffic goes to the ...
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3answers
473 views

How to make sure that in case of our mail server being unreachable (connection down) mail still gets queued and resent once it's back up?

We have had some issues with losing internet connection once in a while. Normally that would mean our mail server is unreachable and incoming email is bouncing. We've set up MX Backup (second MX ...
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1answer
356 views

Best way for Linux site and Database redundancy

I am looking to set up a redundant network that uses a load balancing solution to redirect traffic between two servers. The load balancer I will use is HaProxy. Example: Traffic -> Haproxy -> Server1 ...
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1answer
405 views

In equipment with dual PSUs, how is power draw balanced between them?

In equipment which has dual power supplies - e.g. a server - how is power draw balanced between them? Will they be "active/active", with load evenly spread between both PSUs? Or will they be ...
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3answers
575 views

Domain servers and redundancy

We have just setup our server (although I may be reinstalling it from scratch to use 2008 rather than 2003) and we are now looking into redundancy options. The best option I can see would be to have a ...
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5answers
195 views

Best way to add a second server to existing site in case of downtime?

Well my $379 dedicated sever just went cold again for the second time this month. I need to find a way to get another server going at a different provider that I can just flip on in case this happens ...
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8answers
2k views

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
1k views

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
336 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
557 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
65 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
236 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
1k 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
334 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
115 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
555 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
290 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
997 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
105 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
526 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
102 views

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 ...
5
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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 ...
2
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1answer
289 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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3answers
247 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
101 views

How do you ensure that two data network links have no SPOF?

How do you ensure that two data network links have no SPOF (Single Point of Failure)? We are working on a datacenter network connectivity and need to ensure that there will be no SPOF. We will have ...
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1answer
940 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
468 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
1k views

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
4k views

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 ...