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Questions tagged [redundancy]

In engineering: 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. In information theory: It is the number of bits used to transmit a message minus the number of bits of actual information in the message.

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Join two routers / internet connections under one SSID

I have two networks. A & B. Both A & B have WWW access via independent ISPs. A is a fast network. B has the printers. In theory I'd like to join the networks under one router/SSID and use ...
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12 views

Hypervisor Type 1 Virtualisation on hardware on different networks?

Is it possible to run Type 1 Hypervisor virtualisation on hardware running on completely seperate networks to migrate different instances between hardware for redundancy and load balancing in real ...
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2answers
64 views

Is there a redundant storage method that handles drives of multiple sizes well? What about growth?

I'm looking for something redundant I can just plop on a server with a bunch of garbage drives that just works without the smaller drives crippling the capacity of the larger drives. Lets say I have ...
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LAN on 2 locations with weak link - how to set up fallback DHCP+RADIUS if there's a disconnect between the locations?

The site concerned is small and it's long, thin and winding, without consent to drill holes. There's an area affected by this, which has a couple of file servers, and 2 sporadically used PCs. To be ...
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1answer
340 views

Is IPv4 anycast DNS within a single LAN possible?

I am wondering whether it is possible to use IPv4 anycast to have multiple computers in the same IP subnet handle requests from other machines also in the same subnet. I have two DNS servers on my ...
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1k views

Directly connecting two NAS boxes

I have two NAS units: a Synology and a QNAP. They are both connected to my router via a switch, but since both have spare Ethernet sockets, I guessed that they could also be connected directly, ...
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217 views

OpenVPN with VRRP on tap device?

I'm trying to set up HA cluster with OpenVPN tunnel however there's one small problem - whereas VRRP on LAN interface is not a problem, I struggle with VRRP on tap device. keepalived fails to start ...
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1answer
79 views

Create a RAID file server on Linux

Originally asked on Server Fault here, but I was told to move it here. I have an old PC which I want to use as a file server in my office. I connected two 500GB HDDs and one 300GB HDD to it. Now I ...
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147 views

Master-Slave Two Identical Macbook Pros

I am looking for a way to master-slave two identical (hardware, os and disk image) Macbook Pros such that any interface actions made by the user on the master MBP with be sent to the slave MBP (via ...
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1answer
385 views

Duplicate ethernet cables for redundancy?

Between 2 standard Ethernet switches I want to run 2 Ethernet cables to give some redundancy should one of the cables fail: Will this setup cause any network issues? Will I need to use managed ...
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1answer
614 views

Create a simple redundant network

I am trying to setup a simple home network with an element of redundancy. I have two Ubuntu servers, each fitted with dual NICs. I also have dual TL-SG1016DE simple smart switches. Both switches ...
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219 views

if one nameserver goes down, does that periodically reduce query performance?

If I have multiple NS records for a zone, and one of those authoritative name servers goes down for an extended period of time, does that occasionally slow down all queries because the recursive DNS ...
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64 views

When using Border Gateway Protocol (BGP), who are you connecting to?

It is my understanding that in order to get an AS number from ARIN (https://www.arin.net/), one has to own a class C network of IP addresses. It sounds like once an AS number is obtained from ARIN (...
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How can I know ASAP when my PC loses Internet connectivity and I'm away from the PC? [duplicate]

I have a PC with a USB humidity logger, that measures humidity in our factory. When the humidity is too high, the PC sends me an email alerting me to the problem. Sometimes the internet goes down, or ...
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1answer
82 views

How can I know ASAP when my PC loses Internet connectivity and I'm away from the PC [closed]

I need to know ASAP when my PC loses Internet connectivity. It is of no use to me if my PC waits until it's back online and then emails/SMSs me that service has been restored. Is there a way to ...
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54 views

What (if anything) do I gain by mirroring partitions on the same USB drive?

I have a small amount (a few dozen items of a few kilobytes each) of essential data to store, which I will need to access over the coming decades. While the data is highly confidential, its value to ...
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93 views

Network structure for dual redundancy

Company is looking to upgrade their network with new equipment and while at it, I'd like to architect it to make it more secure, faster, etc. The Agg Switch will have 1 connection to each Core Switch....
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1answer
3k views

Is a RAID1 (mirror) with 2 x 4TB drives and ZFS (through freenas) okay?

I'm looking to create a freenas RAID1 using two 4TB drives. It's going to be my primary location for a generic backup location (use rsnapshot for local files and keeping computer dd'd images) and I'...
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What is the other alternative technique of RAID? [closed]

I've been searching about this topic but I keep getting RAID only. I was told that there is another technique for data recovery and redundancy that replaces RAID. Kindly, can someone enlighten me. ...
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101 views

Prevent data loss through degradation, by making redundant copies to disc

I am about to store my PGP key to a 700MB disc. The key is (compressed) ~ 7KB in size. That is a whole lot space not used. A whole lot space that, if filled, could enable my drive to get at least one ...
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163 views

How to setup redundant ejabberd servers?

I currently have an ejabberd server running at domain A. It has a bunch of users with accounts like xyz@A. I want to setup alternative servers so that if A is down, clients can transparently use ...
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459 views

Proper network architecture for fault tolerant multi WAN multi building WLAN setup

I need help with deciding the correct network architecture for a guest WLAN deployment. We have 3 buildings, and each of them has its own LTE router (Mikrotik RB411U) connected to an Ubiquiti ...
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54 views

tahoe-lafs: one full copy of every file per server

I am attempting to use Tahoe-LAFS to make data available on all the machines I have set a share up on. At the moment, there are two machines acting as storage nodes. I will soon be adding a third. ...
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323 views

reliable/redundant PSU for SOHO server build

I am after reliable SOHO server build. I went with ECC RAM, quality NAS-grade harddrive and now I am looking at the PSU. I cannot seem to find any good redundant PSUs that would fit into the ATX form-...
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42 views

Is there a way to use the empty space on a CD image to enhance error correction (for example entire second copies of file)

I need to write a single file to a CD and the rest of the space is just going to be left unused. Is there a way to use the rest of the space to enhance the chances of the file being recoverable even ...
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2answers
75 views

DNS records: redundancy, and auxiliary servers

I have a domain, this domain points to a front end server. I have two front end servers, one ddos protected intreppid, with 20 GB/ps, other protected with secured servers from 2 to 10 GB/ps. So a DDOS ...
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5k views

Is a home NAS reliable to keep your data on (no other backups)?

The question came up while I was thinking to move some data (e.g.) pictures, old but important other data solely to the NAS (private use, no business level). My NAS is a simple 2 disk RAID system. I ...
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1answer
692 views

What GPT partition type to use for protecting DRBD metadata?

I'm planning to install a DRBD device on a (replicated) disk with two GPT partitions. DRBD requires some space for (preferentially "internal") metadata at the end of the underlying device. I'm ...
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2answers
1k views

Adding parity to backup dvds

I am backing up about 1.8GB of pictures to a dvd, but because over half the disk is free, I would like to add parity of the free space so that data can be read even after some data corruption has ...
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65 views

Intra-disk redundancy options

I have enough single disk systems deployed in harsh-environments that https://en.wikipedia.org/wiki/Bit_rot is a problem. Disks get corrupted regularly. My question is, if I'm willing to sacrifice a ...
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1k views

Is there a type of redundant disk filesystem that allows for some loss of data?

I'm building a media server on a budget. Currently, the design is to have four 500GB disks in a JBOD-type format giving me one large 2TB store. The problem is if any disk fails, I lose the whole array'...
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2answers
1k views

How to wrap an UDP connection to improve resistance agains packet loss?

Suppose there is UDP connection that does not expect much packet loss. Are there already tools that allow wrapping a UDP connection to gain more reliability at expence of bandwidth and overhead, for ...
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1k views

What is the risk of removing old Python versions on OSX?

I have a stock install of OSX (10.6). It has a whole bunch of different versions of Python installed: versions 2.3, 2.4, 2.5, and 2.6 came stock with the system. I can view them all in /Library/...
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103 views

set static Network settings, enable a wifi adapter

Here is my scenario, I have a computer with a LAN Connection and a WiFi Connection, running Windows XP Pro. I have a local network router (WRVS4400Nv2 from Cisco) with Wireless access and a separate ...
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1answer
81 views

ADSL Connections

Can you have two ADSL connections on a single phone line? Or by law of IT, do two Broadband connections require two separate phone lines and BT master sockets?
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1answer
812 views

Can I ensure data redundancy on the server when I use RSYNC?

Let's say I have server which provides a mission critical services, these services rely on data which are synced from another server. The question is whenever I can assure data redundancy on the ...
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1answer
314 views

Setting up Raid 1 Array for Home Server

I'm not sure if this is even possible, but it's worth asking on here! Essentially I have a old machine at home (well, not old hardware wise, but I recently built a new gaming rig), which I decided to ...
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2answers
2k views

What should I do when i get this data cyclic error trying to copy files?

I was trying to copy a file from my local hard drive to an external hard drive and i am getting this error. Cannot copy IMG_9212: Data error (cyclic redundancy check). Should i be worried about my ...
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4answers
3k views

Linux software RAID robustness for RAID1 vs other RAID levels

I have a RAID5 array running and now also a raid1 that I set up yesterday. Since RAID5 calculates parity it should be able to catch silent data corruption on one disk. However for RAID1 the disks are ...
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566 views

Redundant default gateways on LAN

I have two default gateways in my network: 192.168.1.1 and 192.168.1.2. Is there a way to make Windows clients to detect the dead gateway and chnage over to the wowrking one automatically? My gateways ...
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6k views

How does RAID 1 determine whether a disk is corrupted?

I've built a RAID 1 array of 2 disks, A and B. That means that every bit on A is equal to a bit on B. If one disk fails, I can safely retrieve my data from the other disk. But then I started ...
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1answer
1k views

Redundant CTRL-SPACE proposal in Eclipse

How do I remove the redundant Ctrl-Space proposal in Eclipse? SWT JPA JAX-WS etc. Example: I just need Java standard first time click Ctrl-Space proposal.
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2answers
516 views

DFS for a several small clusters over WAN

My friends and I all have TBs on our system(s). None of us have any full backups which are geographically distributed however, because at that amount of data, solutions such as Dropbox, S3, et al. are ...
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Can Linux scrub memory?

Does Linux have a mechanism to "scrub" memory? e.g. testing the memory and marking areas as dirty if they fail so that the system can continue to operate "safely" even with bad ram chips installed?!
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2answers
115 views

Hard drive configuration advice

I've got a few hard discs that I'd like to put in some sort of redundant configuration. Their sizes are: 600 GB 1 TB 2 TB I'm not sure if this is possible, but I'd like to be able to abstract the ...
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2k views

How long will an unused hard drive store its memory? [duplicate]

Possible Duplicate: How much time until an unused hard drive loses its data? I have a broken laptop, and it's the motherboards fault that it can't turn its power on. The laptop has been stored ...
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1answer
942 views

Adding redundancy to unused space of a DVD

I have a 900 MB file and I'd like to safely archive it on a DVD. As you can see 3/4 of the space will be empty. Besides the obvious possibility to just write the same file with 4 different names is ...
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1answer
576 views

What is the practical value of redundancy in zip files?

How is redundancy implemented in zipping, and how do I benefit from it? I'd assume it consists of something like storing the lookup tables twice so a single defect does not invalidate the whole rest ...
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2answers
1k views

Automatic failover of two internet connections Mac OS X

Is there any way to set up an automatic failover for internet connections within Mac OSX? Basically the main connection would be ethernet or wifi and if the main connection goes does, it would switch ...
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4answers
1k views

RAID-like filesystem for heterogeneous set of hard disks

During the last years I have accumulated a quite heterogeneous set of hard disks of different sizes and speeds for storing my private data. I'm planning to put them in a self build Linux filer to ...