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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How to debug/fix a php/apache segmentation fault while using memcache (redundant) for session storage?

os: debian squeeze (up2date) 2 apache mod php webserver 2 memcache server i have to apache mod_php nodes which use two memcache server for redundant session storage (used variant 3 from ...
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2answers
500 views

How much power draws a redundant PSU?

One supermicro enclosure comes with "3 SP382-TS 380W Power Modules for a total of 760W". 2x380W = 760W, okay, but there are 3! So where is the missing third 380W equalling to 1140W?? Is it ...
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2answers
75 views

Adding Redundancy to Win 2008 and SQL Server

We have an Amazon EC2 Windows Server 2008 with SQL Server running Email2Database and another SQL-based windows application. There is a lot of critical data on this box and we need to make sure that ...
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4answers
382 views

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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3answers
228 views

What hardware & software consideration does a major website require to properly manage 1000+ servers? [closed]

Sorry for such a high level question. I understand the basics of server load balancing, but the concept of managing 30,000 servers is a bit foreign to me. Is it really just the same concept of ...
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2answers
149 views

Disk Redundancy across different server

I have 3 servers, all with the same specs: Intel CPU 8 GB RAM Linux or BSD Single 2TB desktop SATA with more than 10K Hours of operation, with only less than 300 GB Used My provider cannot install ...
2
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2answers
533 views

SSD redundancy via HDD

Is there a way to guarantee redundancy to an SSD using an HDD? Raid 1 is the best choice to guarantee redundancy in HDDs, but SSDs are too expensive to guarantee redundancy via RAID. If I was to ...
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2answers
340 views

Overview of multiple mx server set up

Would someone please show me the overview of how multiple mx for a single domain is set up to communicate with each other? I am not talking about how to configure the postfix or DNS mx entries, I am ...
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1answer
55 views

Is the Blackberry “Move Server” command a reliable way to achieve redundancy?

BES supports moving more than one user in a domain to an alternate server as shown in the image below. Does this mean I could achieve some level of redundancy by moving users from one BES server to ...
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1answer
123 views

Cname and Amazon S3 failure

I had a quick question. If you set up a cname for your amazon bucket and lets say your main amazon s3 bucket goes down, does cname you created serve files, in other words, do your files get redirected ...
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3answers
214 views

Should redundant servers have exactly the same configuration, or slightly different?

If you provide a service on two servers to ensure high-availability, is it better to configure them in exactly the same way, of instead should you introduce slight differences to prevent "freak ...
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1answer
801 views

Redundancy for WordPress sites

For static websites I'm using HAProxy (one master, several nodes with static HTML files on them). What services in addition would you recommend to allow WordPress sites to be hosted in the same way in ...
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3answers
277 views

How to use a cloud to host web sites?

To host web sites currently we are using dedicated linux boxes hosted in the UK. But managing them is a nightmare, backups, massive loads, downtime etc... I was looking into OpenStack which was ...
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2answers
66 views

Can we route video on my redundant link while the primary is up and turn it off if the primary fails over to secondary?

We have a remote location that is currently routing data over a satellite connection. I am adding a cellular fail over if the satellite goes down. I have been asked to install video cameras that ...
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1answer
242 views

Two trunks from two switches to router

I want to connect two switches with 6 vlans to a router. Both switches are connected to other switches and are there for redundancy. Router doesn't let me put same default gateways on both interfaces ...
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1answer
77 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
176 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 ...
2
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1answer
427 views

Redundant NFS Setup?

Is it possible to create a fault tolerant, redundant NFS server (e.g. master/slave)? Several of my web servers mount their WEBroot directories from a single NFS server (which is regularly backed up). ...
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1answer
153 views

Mac Server (Snow Leopard) NIC Redundancy on Separate Switches

I have a Mac Snow Leopard Server with 2 NIC's. Each NIC is plugged into a separate physical switch. Currently each NIC has it's own IP, but I would like to setup redundancy so that they communicate ...
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3answers
1k views

redundant nfs share

We are storing files on a network share, our application is mountig this drive using nfs. Now we have the requirement to have this drive redundant. We can add a second server and then synchronize ...
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1answer
236 views

HP P410i as online spare

Is it possible to have dual P410i SAS controllers and use one for a online spare? I am fairly new to HP servers and I will be setting up a new G7 for production use. I have been reading about HP's ...
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1answer
501 views

What is the industry standard solution for linux web server and mac file server failover systems?

I am a web developer at my company and am therefore qualified to be an IT guy, apparently. I have a single Ubuntu web and file server currently, but I want to break up the server tasks onto two ...
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4answers
429 views

MySQL Redundancy for High-Availability over the internet

I am testing out some infrastructure options before I start writing a web application. I would like to have two separate MySQL database servers at different physical locations, but if one of them ...
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1answer
4k views

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 ...
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1answer
718 views

Redundant Mailservers [duplicate]

We recently had a harddisk failure on our mail server (debian/postfix/courier) so I'm researching a way to build redundancy. The first way I found was to setup multiple mx Records in the DNS Server ...
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2answers
747 views

PowerConnect switches, Juniper firewalls and esx redundancy

Let me preface this question by saying that I am a developer and have basic knowledge of networking. My current job requires that I wear many hats. I am building out a DataCenter for our SaaS ...
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3answers
168 views

Multihomed email

Our primary MX record points to an external server which handles spam filtering, thereafter the mail is pushed to our internal mail server. The mail is never stored on the external server for longer ...
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5answers
7k views

Can you set a backup ip for your server in DNS?

Is there a way that the DNS protocol can natural hold a backup A type server address, like a backup name-server or mail server ? After googling i just got results on backup nameservers. If there isnt ...
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2answers
203 views

Two mirrored database servers, or one twice as powerful

I'm looking at setting up a seperate database server for one of my applications, the application currently runs on 3 servers; 1 frontend server and 2 application/database servers. But for performance ...
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2answers
189 views

Cloning Two Windows Servers

Basically I have a server running MSSQL, MYSQL, APACHE, IIS, ORACLE, PERL and other windows services. I am looking for some hardware solution that would allow me to clone a server on to a back up and ...
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2answers
270 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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3answers
2k views

Is it possible to use mixed 110V / 208V power on a single server with dual power supplies?

Is it possible to run a dual power supply server with one PS plugged into 110V, and the other power supply plugged into 208V? We've asked the vendors and they say they've never tested it or some other ...
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3answers
8k views

How do you set up redundant servers?

To the sysadmins out there, I'm trying to get an idea about how you go about maintaining redundant servers for small projects. The modest number of servers in my mind is two, and three main essential ...
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1answer
174 views

Server redundancy or failsafe for small single office server

We run a local server in our office, and have a domain name pointed to it so we can test out sites we build. We also handle some image hosting for clients for emails. Since it's a single server, if ...
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3answers
344 views

Switch Redundancy for iSCSI

I am about to implement an iSCSI solution on our network. The thing that is bothering me though is that we are only using 1 switch from the SAN to node connections. Since each node has 2 NICs, is ...
2
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1answer
201 views

What steps can I take to ensure that my rails app on heroku isn't effected by another ec2 outage?

My app is a victim of the recent EC2 outage and is still offline. The outage has negatively effected my business and the relationship we have with our clients. I'm hosting the app on heroku with their ...
2
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1answer
565 views

Effects of having a rapid ARP flush

So the scenario is we have a web server at our colocation. In front of that web server are two SonicWalls and two L2 non-stacking managed switches. We're trying to find an efficient way to set up ...
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6answers
3k views

Redundant Load Balancers for Windows-based Web Servers?

I'm having some trouble trying to figure out the technical details of the below design; specifically in the area of the redundant load-balancers. The web servers are running Windows Server 2003 R2 64 ...
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2answers
256 views

Placing UPS in front of STS; Connecting Dual PSU to same PDU

The site has 2 x 16A @ 230V, each server/SAN has dual PSU set up. Options: 1) [2 x 16A] ---> [1 x STS or ATS]----> [1 xUPS]---->[2 x PDU]----->[DUAL PSU] As can be seen the server is actually ...
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1answer
2k views

Windows Server 2008 multiple domain controllers?

We currently have a domain controller which has the profiles etc. for around 30 users. It is also the local DNS server and file server. As it's our only Domain Controller, if we ever have to restart ...
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2answers
429 views

IIS7: one domain, one IP, two servers, one as fallback

I would like to have a setup where I can tell any of two servers to be the "main"-server on a specific IP (for redundancy reasons). Both servers should be accessible at any given time but only one ...
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2answers
346 views

Cisco 6500 redundancy

Which of the following methods is best for redundancy in a Cisco 6500? Two Cisco 6500 chassis each with a single Sup720 and other modules. One Cisco 6500 chassis with two Sup720 modules and two of ...
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1answer
732 views

“Simple” Failover to a Geographically Separated Server?

I've been reading about DNS failovers and a bunch of other technical terms however I'm a bit of a newbie in this so it all sounds Greek to me. Basically here's what I just need: I have two shared ...
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1answer
120 views

How to Add a Secondary Server, Correctly

Just wondering if a network of approximately 15 users has only 1 Server Running Windows 2003 and wanted to add a "secondary server" so that in the event the "primary" fails for any reason the ...
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2answers
183 views

Two hosting providers running simultaneously… possible / not possible? good practice / unnecessary?

For the sake of their reputation, I won't mention the names. But I'll just use: Business I worked for previously - ABC Web Dev Hosting company they used - XYZ Hosting I recently found out that XYZ ...
11
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8answers
3k views

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 ...
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7answers
7k views

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 ...
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3answers
7k views

Is it possible to make redundancy on HAProxy server?

I am going to use HAProxy as a load balancer that will balance requests on 3 application servers. But what if balancer server (HAProxy) fails at some point? I was thinking of cloning the first ...
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2answers
2k views

Failover/Load balancer for WHM/cPanel [closed]

I have a simple question for which I have not been able to find a simple answer. Here's the scenario: Server 1: WHM/cPanel with multiple accounts/dbs Server 2: WHM/cPanel with multiple accounts/dbs ...
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2answers
749 views

Howto create redundant network on server

I am in the situation where I have a number of CentOS Linux servers which all have two NIC interfaces. Currently one of these interfaces is used for internal communication, the other is used for ...