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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2answers
24 views

Internet connection redundancy with 2 ISP

Setup is 1. One Linux server running web server and ftp server. 2. Two ISP which provided a range of public IP address 3. From the client(browser) side we can set only one of IP/domain name as ...
0
votes
2answers
54 views

UPS systems in parallel for redundancy and/or capacity, generator as backup, ATS,

I am about to upgrade our server room's power plan and would kindly ask you for your help with a proper, optimal design / advice on "good practice" approach. Please note that our business is small, ...
0
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0answers
12 views

several domain controller logon

I've got two domain controllers. The master is DC01 and slave Fil01. I got that problem, that some computers logon over the slave dc and not the master. How can I set the order or prevent them on ...
9
votes
3answers
299 views

How to make redundant load balancers?

I understand that the purpose of load balancers is to balance load between your servers and keep track of instance health, etc. But what if load balancer itself fails? How do you set up redundant load ...
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votes
1answer
41 views

How I do to run only a software in more than one computer? [closed]

I need to run a unique instance of a software in more than one computer, how I do this without a centralizer server? For example: 4 computers interconnected by the local network, 2 of then has "the ...
1
vote
1answer
41 views

Setting up a small network with a redundant WAN setup

Asked on the network stack but referred here, partly because lower grade equipment. Small office and we are trying to piece together a network with our two wans (diff ISPs) a switch and a few ...
0
votes
0answers
75 views

How to setup failover and load balance when two WAN links are available each one with a single public IP

I have read the question in here but I feel it's not exactly my setup. I have two physical ADSL modems (not a single one like as in the picture of ...
0
votes
0answers
86 views

Layer 3 switch redundancy solution (with vlan's, stp)

So basicly I have a setup which I want to get to work but i'm unable to. It's possible I am overseeing a lot of things but let's get to it anyways. The current situation is a network with 4 switches ...
21
votes
5answers
2k views

How to protect against loss of server on a budget

I'm a small company on not much budget providing websites and databases for charity and not-for-profit clients. I have a few Debian Linux VPS servers and ensure I have daily backups to a different ...
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votes
1answer
110 views

Teaming the 2 ports of a hp 361T pcie Dual port GB Nic [closed]

We have a network with two switches stacked for redundancy. We have a HO 36LT PCI-e Dual port NIC and an Intel x520 10GbE port adapter. I want to be able to assign one IP address for both ports. I ...
1
vote
0answers
426 views

Creating redundant IPSec connections using OpenSwan

I have a linux (netkey) instance with openswan installed, the instance has two connection to the same IPSec peer that needs to act as redundant connections. both connections' properties are the same ...
-1
votes
1answer
59 views

What are common server architectures to build a reliable website [closed]

Sorry, if my question looks too general, but I am looking for an answers to specific problems that I listed below and would appriciate any help. My website is growing in popularity and I would like ...
2
votes
1answer
75 views

“Hot data” and erasure coding: how to know if it is efficiently handled?

It is well known that erasure coding adds extra complexity because of encoding and decoding operations. Due to this drawback, most of cloud services recommend to use data replication for hot data and ...
-1
votes
1answer
47 views

Rapid failover from one data center to another when the first goes down?

I'm building a global CDN and have a DNS service that will direct customers to the closest server. However I need rapid failover if one of the data centers e.g. Germany goes down users need to be ...
3
votes
3answers
756 views

Evaluating uncorrectable ECC errors and fallback methods

I run a server which has just experienced an error I've not encountered before. It emitted a few beeps, rebooted, and got stuck at the startup screen (the part where the bios shows its logo and begins ...
12
votes
4answers
805 views

Is there any value in protecting both rack power feeds with their own UPS?

I've done some looking and have not found a satisfactory answer to this question. When is it necessary or suggested to use an independent UPS (on it's own mains branch circuit) for each power feed to ...
-1
votes
1answer
102 views

Does chassis mid-plane provide load balancing for power supply

I am new to blade chassis management, and i want to know what is the purpose of mid plane apart from connectivity. Does it provide load balancing among the power supplies. If so does that mean it ...
3
votes
1answer
152 views

Howto do VCSA redundancy?

We are currently in the process of setting up a new VMWare environment which is now only in lab phase. We are studying the possibility to have a vCenter cluster with an active and a ...
8
votes
5answers
896 views

Hot spare host vs cold spare host?

We have several hosts where we have an identical hot spare host, which is patched and updated so it is very close to have to same software and config. In case of failure the network cable is switched ...
0
votes
2answers
28 views

Providing redundancy for processes on different servers [closed]

Say I have for example 5 physical machines with similar resources (CPU speed, RAM and storage) named s1, s2, s3, s4 and s5. If I have a processes running on s1 but then s1 fails somehow, how can I ...
0
votes
1answer
540 views

CARP Virtual IP does not ping in virtualized environment

We have three physical machines with SmartOS on them in a LAN. Two of them, 10.40.0.30 and 10.40.0.240 are hypervisors with two pfSense-based virtualized gateways on them. These gateways have ...
1
vote
2answers
69 views

Implementing DNS Redundancy - Web Hosting

After our domain registrar/name server host went down we have found that DNS is a major single point of failure as its also taken down all of our email (Office365), web, hosted services etc.. I want ...
2
votes
4answers
863 views

new hyper V High Avaliability setup and SMB 3.0 storage

I am looking at building an new 2012 R2 with Hyper V setup, everything has to be HP hardware. 2x HyperV 2012 R2 servers running 20-30 VMs. These will be dual 6 core xeons with 128gb of ram. 2x 2012 ...
3
votes
1answer
1k views

SonicWALL HA w/ Dual WAN HSRP from two redundant switches

We're adding two SonicWALL NSA 2600 firewalls to our current setup. We currently get two WAN connections from two separate Cisco routers running on the same external subnet with what I believe is ...
1
vote
2answers
678 views

Redundant routing (active/backup) on linux

I'm currently trying to setup a redundant routing on RHEL 5. The target goal is to have a primary route to a subnet and a backup route to that subnet, to be used only if the gateway of the primary ...
0
votes
1answer
74 views

Where can one find good documentation describing memory-rank “sparing”?

Where can I find good documentation describing memory-rank "sparing" (for computer-hardware memory-protection configurations)? I'm seeking to clarify what benefits it provides and how it's typically ...
3
votes
3answers
340 views

How much failover redundancy is enough? [closed]

I'm working on a client-server system where all clients currently submit their transactions to essentially a single west-coast IP address to reach what is called the "gateway" application. The ...
2
votes
2answers
71 views

redundancy in a single SCSI target

following-on from my earlier question about resurrecting an ancient Intergraph 6800 machine (licence file for extra logins on ancient Unix (CLIX) system), the original problem was a failed hard disk ...
2
votes
1answer
755 views

HyperDB Configuration Master/Slave

Running on server 2008 R2 IIS 7.5, with a MySQL Master/Slave (also on server 2008 r2), and WordPress 3.7. Is it ONLY compatible with wordpress 3.5.2? If that is so is there any other plugins to allow ...
0
votes
0answers
26 views

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 ...
5
votes
3answers
3k 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 ...
1
vote
1answer
258 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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votes
1answer
209 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 ...
1
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1answer
223 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 ...
0
votes
2answers
467 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 ...
8
votes
1answer
1k 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 ...
0
votes
1answer
98 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 ...
-1
votes
1answer
93 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 ...
2
votes
1answer
395 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 ...
3
votes
3answers
404 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 ...
5
votes
1answer
205 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 ...
-5
votes
1answer
144 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 ...
0
votes
1answer
43 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 ...
0
votes
1answer
139 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 ...
0
votes
1answer
93 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. ...
2
votes
1answer
443 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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votes
3answers
103 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 ...
2
votes
2answers
881 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
votes
1answer
477 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, ...
1
vote
1answer
406 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 ...