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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Providing internet redundancy for our colocation provider

My company recently had an network outage at our colocation facility that is serving our main website. The outage was caused by an upstream switch failure. I was told by my ISP (who provides us with ...
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2answers
278 views

Is it possible to do storage without RAID and unnecessary redundancy?

I'm building multiple storage nodes for Riak database. Each node contains 20-40 x 2TB drives. Riak replicates each save to 3 nodes so there I have redundancy. Now the question is that what's the best ...
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1answer
102 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 ...
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1answer
96 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 ...
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1answer
30 views

Is it feasible to switch DNS A records to point to a backup provider in case of failure?

Is it feasible to switch DNS A records to point to a backup provider in case of failure? Instead of relying on one provider/datacenter. I know there is a lag due to ISPs caching the records, but ...
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1answer
45 views

Speed up EIP reassignment

I have a real-time application running on an Amazon EC2 instance. I'd like to implement master/slave redundancy with a VPC, a second instance and keepalived. So far it's working reliably, but in the ...
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1answer
107 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 ...
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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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1answer
80 views

Redundance for different processes running on the same server

We have a system consisting of different components/services like database, webserver, fileshare, some self programmed daemons, etc. We now have the requirement to make all components/services ...
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1answer
178 views

Amazon EC2 SQL Instance with Cheap redundancy

I'm looking at transitioning from a dedicated hosting provide to Amazon's EC2 instances. The website is an asp/asp.net website with SQL Server 2008 as it's backend. It has zero redundancy as is ...
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1answer
22 views

Need some clarification on a NIC functionality on a Dell Poweredge r610

Quick question. I'm trying to understand the NIC functionality of this server. NIC specs from manual: My question is, do the two broadcom controller chips provide fail-over redundancy? For example, ...
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0answers
803 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 ...
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0answers
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Redundant Firewalls And Switches HSRP and CARP

I currently have planned 2 x uplinks (HSRP Active/Standby) 2 x pfsense firewalls (Carp Enabled) 2 x layer2 switches Please criticize or offer help on the correct way to do this. I have a feeling im ...
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0answers
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keepalived should vote more relaxed, is raising garp_master_delay and/or advert_int the solution?

Im using keepalived on two machines. The one being the master establishes an ipsec tunnel. Sometimes (once a month or less) the vrrp packet was missed, and the backup takes over, establishes the ipsec ...
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0answers
52 views

Intel server SC5300LX+SE7520BD2 won't boot after removing a second PSU

I have an intel server SC5300LX+SE7520BD2 with 1+1 redundant PSU (Delta electronics C46098-005). As one of the PSU had an amber led lightning, I decide to check the part-number and I did this by, ...
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0answers
31 views

How setup redundant static ip Internet for outages

We host an iis 7.5) windows site on a comcast business static IP (in office). the internet goes down sometimes and I;d like redundancy. I cant find the proper way to add a second internet ...
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0answers
66 views

Multi Path VRRP with keepalived

I'm migrating from an old heartbeat setup to using keepalived at the moment and currently I can't find how to replicate the heartbeat capability of using multiple links as cluster interconnects in ...
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0answers
29 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 ...
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0answers
169 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 ...
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0answers
139 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 ...
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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 ...