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Questions tagged [redundancy]

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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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 server. If that server has problems, all the sites…
Jeff Atwood
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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 forums, is, that there is a theoretical possibility…
ChrisZZ
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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 balancers? (load balancing load balancers?) I…
Sherzod
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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 VPS than the one the service is hosted on. Recently…
artfulrobot
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Do you lose everything when you have a hard disk failure in a multi-hard disk LVM that does NOT use RAID?

I'm debating about using LVM for a media/file server because I would like to combine multiple physical hard disks into one volume. I do not wish to use any RAID in my LVM so my question is: If one of the multiple hard disks in my volume were to go…
Fujin
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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 a rack? To elaborate; when using servers with…
cathode
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Is it possible to have a secondary managed DNS provider to quickly delegate to when DDOS attack on our *primary* external DNS provider happens?

So our DNS provider, every so often, experiences DDOS attacks on their systems that causes our front-facing web sites to go down. What are some options in terms of reducing dependency on a SINGLE external managed DNS provider? My first thought was…
Emmel
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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 the onboard RAID chips. But I've heard a lot of…
amarillion
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Load balancing Apache on a budget?

I am trying to get my head around the concept of load balancing to ensure availability and redundancy to keep users happy when things go wrong, rather than load balancing for the sake of offering blistering speed to millions of users. We're on a…
Industrial
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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 a geographically different location, but also…
Thomas Vander Stichele
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Alternatives to Dell's mirrored SD card module for booting a small OS from flash?

Dell offers an add-on hardware card for some of their servers that provides a poor man's RAID1 between two SD cards (one card gets all the reads until it dies, writes are mirrored) for booting a simple OS that has very little write load to the OS…
Shane Madden
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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 domain?
GetFree
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Can you set a backup IP for your server in DNS?

Is there a way that the DNS protocol can naturally hold a backup A record server address, like backup name server or mail server records? When searching for this I only saw results on backup nameservers (NS records). If there isn't a way for DNS to…
kjones1876
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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 one connected to its own UPS. They can both detect…
Falken
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Is Ceph possible to handle hardware RAID arrays (LUNs) as OSD drives?

I am pretty new to Ceph and try to find out if Ceph supports hardware level raid HBAs. Sadly could not find any information. What I found is, that it is recommended to use plain disks for OSD. But this pushes the requirements to the PCIe, the…
cilap
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