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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hosting a service locally and on amazon ec2 with auto-routing

I have a java REST service which is very CPU intensive. The service serves a website. I would like to host the service on my local machine which has 8 core 16GB RAM, SSD as the main storage and high ...
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3answers
4k views

Is round-robin DNS a possible solution for high availability?

Let's say I have 2 IPs for a given domain (round-robin DNS). If one the IPs becomes unresponsive, will clients try to connect to the other IP? or they will just fail to establish comunication with the ...
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1answer
335 views

Redundant OpenVPN tunnel

I'm trying to set up a fully redundant OpenVPN tunnel, with two routers on each side. All the tutorials I saw (such as ...
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1answer
316 views

Can I implement network redundancy just with static routing tables?

I have a Windows 2003 server which is connected to a router at 192.168.15.1 via 192.168.15.10. I also have a linux server connected to that same router via 192.168.15.90. And I have a direct ...
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1answer
269 views

Redundant web static content storage - what technologies? (small scale) [closed]

Current situation of our static web servers: 2x 2U servers full of SSDs (raid5) for storing data data are written to them only through our applications (*) huge amount of small image files (one ...
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2answers
765 views

web server redundancy in case of network failure

I have a (web) server at a datacenter, which at times (as all datacenters do) has network failures (for like 10-30 minutes). I have a second server at a different company (datacenter) which I could ...
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1answer
2k views

VMware vSphere cluster design for site redundancy

I have a question about the best design for site redudancy when using vSphere clusters. A bit of background info about our situation first though. We are a medium-sized company with two main ...
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1answer
118 views

munin-node send data to more than one master?

I'm in the process of making everything on our server setups redundant, and so comes the monitoring. We have one virtual machine acting as munin master and all other virtual machines are munin nodes ...
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1answer
143 views

How to achieve redundancy with layer 2 switches only in network?

I am trying to find out way to make network design with only simple un-rooted switches which avoid redundancy! I use 2 computers & 2 simple switches each switch connect to one pc & between ...
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1answer
543 views

Simple redundancy setup using two servers in two different datacenters? [closed]

Scope of the question This question is solely about getting a client requesting a domain: example.com to one of the two available servers. How it is handled from there on, is another problem to solve ...
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3answers
502 views

Probability of Blade Chassis Failure, Redundancy

Suppose I have a blade server HP C7000, with three blades. Q1. Is there any disaster recovery technique that provides redundancy between blades? If any one blade goes down the second should come up ...
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1answer
228 views

DRBD for HA Server in Small Office Questions

Backround: We are in need of a HA server in a small office environment and are looking at DRBD to provide it. We only have about 100GB that needs to be on the HA server and server load will be ...
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1answer
152 views

Loadbalance between Heroku and AppHarbor? [closed]

How would you set up simple redundancy between these 2 "cloud" providers? Does a DNS fallback seem reasonable (that would update records when one is down) or would it take too long to propragate the ...
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1answer
47 views

redundancy / load balancing on 2 unmanaged dedicated Windows-based servers

We normally host our dedicated servers in an unmanaged data centre, i.e we just purchase the server and we can manage it ourselves via remote desktop connection. We cannot install / configure any ...
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1answer
175 views

Setting up apache + mysql + exim on new servers. Redundancy/HA/Failover?

We are currently moving our single Linux server to a few other physical Linux servers, and would like to take the opportunity to have some more failover options. Backups are fine, and we don't ...
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1answer
97 views

Software for syncing two folders?

I have a SQL Database that is running 15 minute backups to a folder on the local disk. I also have a maintenance task in SQL Server that's automatically deleting any backups that are over 1 hour old. ...
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1answer
625 views

Same VRRP group, multiple VLAN

Let's say a gateway has traffic between vlan 11 and 22: Gateway 1 -- FastEthernet 0/1.1 -- vlan 11 -- 192.168.11.1 Gateway 1 -- FastEthernet 0/2.2 -- vlan 22 -- 192.168.22.1 Gateway 2 -- ...
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3answers
108 views

Two drives, how can i max reliability and uptime? [closed]

I have an asterisk pbx. It has 2 drives in a raid 1 setup. However if my main drive fails my 2nd won't boot, as it has no boot partition. The most important thing for me is up time. If there is a ...
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2answers
992 views

Server Backup Strategy for Amazon EC2

Where and how should I backup my EC2 / EBS based snapshots OUTSIDE of EC2? EC2 provides a great product with their EBS based snapshots. However it is also a high risk point that someone could ...
6
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1answer
555 views

How do I configure NAT rules when using ASA IP-SLA when leveraging post-ASA-8.3 NAT syntax?

We are currently running ASA9 at a location with redundant ip connectivity. We'd love to configure ip sla so that internet access survives a single carrier outage. I'm aware of the ip sla commands, ...
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1answer
512 views

What is the best option for SIP service redundancy?

From your practical experience, what is the best option for SIP service redundancy? a) one SRV record pointing to a hostname which has two A records b) two SRV records pointing to two different ...
2
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1answer
175 views

Cisco 6500 vss mode upgrade

This is not my network. I'm trying to understand why my cloud provider insists that they need to take down both routers when performing updates. From what I understand they have 2 Cisco 6500s ...
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1answer
292 views

What's the best way to run HAProxy backup as another HAProxy server and avoid cyclical issues

I have several geographical regions for my service deployment, say Region1, Region2, and Region3. Each region has a failover haproxy instance. Each haproxy is configured with several backend servers ...
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3answers
4k views

A-Record Failover?

I have a Fortigate 100D with 2x BT Business Infinity Fibre connections acting as WAN1 & WAN2. The BT lines come with 5 static public IPs each and I have my DNS hosted through CloudFlare pointing ...
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2answers
823 views

Redundancy scenarios for a small network centered around a Cisco 3560X switch

As the title says, I manage a small network which uses a Cisco 3560X as the core switch. We have recently got a 2nd identical switch and I have started thinking about how to add some redundancy to the ...
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2answers
426 views

A and PTR records and redundant Internet connections

Want to set up PTR record(s) to handle the following: Site with mail server (Exchange 2010) has three Internet connections, with the firewall handling load balancing. I know that if the Internet ...
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1answer
453 views

How to setup cluster of virtual machines to host web application with fail-over redundancy?

I would like to know how to setup a cluster of virtual machines to host a web application. We are expecting a high volume of clients connecting. I would like a cluster of virtual machines (or ...
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4answers
182 views

Achieving Five Nines

I am building a web application where uptime is key. I understand that 100% uptime is not realistic but I would like to achieve five nines. I'm unsure as to the most prudent way to accomplish this. ...
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1answer
552 views

Networking: Does slavedisk0 take over for disk0 in the event of a fault?

My bootvar is set to boot up images from disk0. The 6500 series switch has two redundant supervisors. Each supervisor has a PCMCIA card with the exact same IOS images in the 0 slot. The secondary ...
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1answer
351 views

How to setup a failover solution for Windows 2003 SMTP Server?

I'm currently running Windows SMTP Server on a rented Windows 2003 Server VM. There are times when my hosting company network is down and my clients can't send their emails via the SMTP Server host I ...
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7answers
8k views

Probability of Blade Chassis Failure

In my organisation we are thinking about buying blade servers - instead of rack servers. Of course technology vendors also make them sound very nice. A concern, that I read very often in different ...
3
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1answer
2k views

Configure fallback redis server

I am using redis as a cache server. Can I somehow configure multiple redis servers, that the cache is fully functional (read/write) even if some of them go offline? I looked into master->slave, but ...
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2answers
1k views

Record DNS for 2 static ip - fault tolerance

i've a web server in a DMZ reachable from 2 different public static ip addresses provided by 2 different internet connection by 2 different ISPs. I want to create a record let's say ...
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1answer
79 views

Preparing a server for mysql replication and use it as standalone

I want to host an application on a single server running MySQL server. To get the best performance I plan on using a UNIX socket connection (to avoid TCP overhead). Later, I would like to scale up by ...
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2answers
107 views

Domain name to point to 2 different servers

I'm looking to setup cheap redundancy for a website, such that I signup with 2 separate shared hosting accounts. The likelihood of both being down at the same time would be small. Is there a way to ...
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2answers
438 views

Basic redundancy for EC2 (wordpress + mysql)

I've got a website that I would like to add redundancy to. It's not a massive website, and will probably only receive a handful of database updates and/or files per day, however it's very important ...
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2answers
133 views

High available and secure FrontEnd to WebApps behind a firewall [closed]

my question is about proposed implementation of high available and secure FrontEnd to WebApps behind a firewall. The components of the network and their relationships are as follows: 1) 2 WebApps ...
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1answer
104 views

ISP Redundancy Hardware

I've tested Microsoft TMG 2010 to load balance my two DSL lines and it works fine. Can I expect the same level of results and security to be achieved with a less expensive firewall appliance?
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1answer
649 views

Email server - redundant, mobile, and secure [duplicate]

Possible Duplicate: 100% uptime for a web application I wish to create my own personal email server. I can't have any downtime - so I have 3 machines at different IP adresses around the ...
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2answers
226 views

Servers configuration to improve performance and offer redundancy for ASP.NET site with SQL Server

I'm administrating a fairly large website (currently about 300 thousand page views a day) which is expected to grow fast. Currently both IIS and SQL Server are running in a quad core server, with RAID ...
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1answer
171 views

Configure a backup Win 2008 R2 Server

Scenario is a small network with a Server 2008 R2 running AD, DHCP, DNS, Print & File Sharing. We'd like to build a backup server to continue operations uninterrupted should the main server go ...
1
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1answer
485 views

Sonicwall firewalls and redundancy of route based vpns

I am attempting to configure a route based vpn on a Sonicwall TZ device. The datacenter has two public IPs on different subnets (A and B). The remote office has 1 public ip (C). When I configure ...
3
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3answers
758 views

Redundant Linux Servers in Seperate Datacenters

I have 2 CentOS linux servers in separate data centers on each site of the country. These linux machines run a small web sites on Apache with a MySQL backend. There currently is no VPN connectivity ...
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1answer
227 views

How to use Route53, or any other service, to redirect to a “backup” site when the main one is unreachable

I have example.com managed by a DNS server that associates it to some IP address (ip1), owned by a first web server where the full site is hosted. I also have a secondary webserver (with ip2) that ...
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2answers
268 views

Is ntp.ubuntu.com redundant?

Does anybody know if Ubuntu's NTP servers are redundant? If I dig them, I get: ;; ANSWER SECTION: ntp.ubuntu.com. 280 IN A 91.189.94.4 vs. when I dig pool.ntp.org: ;; ANSWER SECTION: ...
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2answers
3k views

Adding redundancy to Hyper-V without a SAN

My organization has two identical servers, HP ProLiant DL380 G5. We do not have a SAN device. Each server has 8x 146GB HDD, and 48GB RAM. One server is currently configured as an Exchange server. ...
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1answer
67 views

Redundant Connection Issue

I'm trying to set up a redundant connection for our web hosting servers. I have a BGP-capable router connecting two lines from two separate ISP's, one fiber (primary), one DSL (failover). I've already ...
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2answers
3k views

Redundant FreeRADIUS + MySQL

I’m working on some web service having it’s AAA implemented by FreeRADIUS + MySQL on Debian. The problem I’m working right now is HA & scalability of RADIUS. If the FreeRADIUS machine or MySQL ...
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2answers
433 views

Strategies for detecting corruption in Greyhole pools [closed]

Are there any good strategies for proactively detecting data corruption in a Greyhole pool. Suppose the following chain of events happens. c:\> copy swiss_bank_account.txt ...
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1answer
147 views

Branch Office Switch Redundancy

We're setting up a branch office with no dedicated IT person (all IT support is remote from HQ) and trying to make the infrastructure as redundant as possible. We've dealt with Internet and power, but ...