How To Keep 2 Servers Synchronized (to Use Failover)
Apr 21, 2009
We want to provide failover service at our server using dnsmadeeasy service.
So we have already buy the "failover server" (running linux/plesk), and now we are looking to find the most adequate / best way in order to keep the 2 servers sincronized, in order that if "main server" goes down, all the traffic can be redirect to the "backup server" using dnsmadeeasy.
on scripts/software to keep 2 linux servers sincronized in a failover setup?
im looking to add failover protection at my main server, in order that if it goes offline, all the traffic can be in a automatic way redirect to a failover / backup server.
For the failover server i was looking to buy a low-cost dedicated server located in other datacenter and have my dns be run at this failover server, but now i have been looking at Cloud Hosting, like Amazon or Mosso CloudServers and as it seems a very stable network, im thinking if it will be best to have setup/running my DNS at a Cloud Host...
So what do you think it would be best:
Option A: 1 main server 1 failover dedicated server 1 cloud (amazon/mosso) virtual server to run DNS
or
Option B: 1 main server 1 failover dedicated server (running the DNS)
way to keep server times synchronized? All servers are in the same location.
For example, a website has two web servers and one database server. What's the best way to keep the time syncd on all servers (they should be the exact same time really)?
I have a client that had an "electrical" problem with his hosting service, and all his sites were down for more than 1 week.
Is there any chance to create some sort of backup servers, on different hosting companies with a service that offer a mechanism of ip redirect in case of main-server failure?
I want to add a DNS Failover automated service at my server, in order that when it goes down, the DNS Failover enters in action and it will redirect all the traffic to a second backup/failover server (hosted at a different location).
So in order to do this i have been looking around and i have found dnsmadeeasy, and i found their offer interesting.
But i still have some question and doubts on how a dns failover service works. So maybe someone can expalin it to me.
My question and doubts:
1 - If i use for example the DNS failover from dnsmadeeasy, i would have to buy 2 servers where one is the principal server and the other is a backup/failover server, so when my main server goes down, the dnsmadeeasy will detect in a automatic way, and redirect all the traffic to my backp/failover server. After my principal server goes back online, dnsmadeeasy will automatic redirect all the traffic to the principal server.
Im i correct? Or i understound wrong how this works?
2 - I use my own Nameservers and i want to continue to use my own nameservers. So if i use dnsmadeeasy services, i will be able to continue to use my nameservers as ns1/ns2 and then i will add the dnsmadeeasy ns3/ns4...as the following example: ns1.mynameservers.com ns2.mynameservers.com ns3.dnsmadeeasy.com ns4.dnsmadeeasy.com ns5.dnsmadeeasy.com ns6.dnsmadeeasy.com
I am planning to rent 2 managed dedicate servers with windows server 2008 and ms.sql 2008. which I will use one for web application and 1 for database server.
why people usually divide them into web and database server? is it for security or performance reason?
Which one you prefer to choose?
- 1 server for web and 1 server for database. or
- 1 server(web and database) and 1 server for failover
In making my plans for my web hosting business I plan to start, I've thought about a failover but wanted to know the best way to set it up.
I would ideally like to start with something like getting a small shared hosting solution (not reseller, just shared) at a reliable hosting company. On this hosting plan, I will host a simple 1 page site that says my company is having technical difficulties, reminds people that data is safe, and provides any contact information accessable (like e-mail/phone/etc...).
I already have DNS setup offsite.
I would like that if my server(s) go down for any reason, whatsoever, that DNS automatically starts serving the temp site.
so if my server suddenly goes down, [url]or [url]suddenly goes to the offsite shared hosting plan.
This would not provide customer site redundancy. This would only ensure that if anything happens to my service, customers have a page available that explains what is happening and has information to contact us to get more details.
We have 2 Cisco PIX 515's in a failover configuration (7.1 series IOS). We have available both a serial failover cable and adequate switch capacity to allow using either the serial or LAN-based approach. We have no current plans to locate the firewalls physically apart.
We have plenty of info on how to configure either, but no recommendation on which is the better choice.
I have a reseller account with a company that often has spontaneous DNS errors, and this, as you know looses us money. I also have a dedicated server running a panel exclusively via IIS. Is there a way I can set up my dedicated (Windows) box and my reseller account in a mirror way, so if one of them fails, the other will take over.
There are no file changes often, more database then anything. Is this possible? Main necessities are:
-Mail Servers
-MySQL Servers
-PHP5
-Cron jobs
(Or, if a shared hosting company can accommodate this somehow and is relatively inexpensive.
I host my own server but need to get a failover server in the case it goes down. Does anyone know of any companies that host failover servers that will run off my own server?
Basically have 2 hosting accounts at different providers...each set-up for the same domain name...and then somehow wtih DNS make it so if host #1 goes down traffic goes to host #2 (which would basically be a splash screen explaining that host #1 is down and will be back soon).
DNS isn't my strong point, but I do know you can do this with MX records...so if the first server fails it tries the next until it gets a working one or reaches the end of the list. I'd just like to do it is A records.
It wouldn't be as simple as setting the nameservers like this would it?
Would it use the host1 nameservers as long as they're online, and if not failover to the host2 nameservers? If so, great, but what if the host1 nameservers are online but the server itself is not.
Assume, a DNS failover service would change the DNS from server 1 to server 2 when the first one is offline. This will be changed quite fast, however isn't it true that some visitors still experience a downtime of a couple of hours (saying that the main server will be offline for 6 hours) as their ISP might not update DNS that frequently?
So basically, what is the added value of a failover service?
What happens if your primary nameserver goes down? Meaning that it goes completely off the net, not even denying dns requests but completely ignoring them.
I'd guess that resolvers would query the secondary NS after a specified timeout, but what is that timeout set to? Does it differ from ISP to ISP? How much of a slowdown are we looking at for end users?
I'd like to create a failover server, a complete and identical copy (as much as possible) of my primary server, which becomes "primary" when the first server dies.
I've been reading a lot about this subject and i've seen an already working method which uses rsync and MySQL replication.
Has anyone managed to create such a system? is there someone with experience or can point me to a relevant web site?
I'm building the infrastructure for a live event site.
I have specced 8 app servers but I'm still unsure with regards to MSSQL.
The site functionality makes a single write to the DB with no reads. A simple option would be to have a MSSQL DB instance on each of the APP servers and simply collate the information after the event.
I've also been looking at the mirroring function of 2005 as it would mean we could get away with two MSSQL servers instead of 8.
Has anyone used MSSQL 2005 Mirroring? Is it easy to setup and maintain? Any caveats?
I'm working for a client who has an e-commerce site currently hosted on a shared hosting solution.
He is now looking for 100% uptime (as near as), so I have suggested that we get 2 VPS and use DNS monitoring to switch servers as required (from DNSmadeEasy).
This is all fine, and the websites files/images do not change often, so I can use rsync every so often to sync these. Not a problem.
What does change frequently is the mySQL db for the site.
I've been looking at MySQL replication, but this seems to be no good. If one server goes down, then the other one takes over, they don't automatically sync themselves after they come back up. It seems MySQL cluster is best, but this needs 3 servers and they all need to be on the same LAN.
I've read you can set MySQL replication to MASTER-MASTER so that it acts like a cluster, and resyncs itself as required.
Well my problem is, we have 2(ABC and XYZ company) internet connection and sometimes, the ABC connection is not active and we're disconnected for about 2-4 minutes interval to get the XYZ internet connection online.
My question is - Is there a software that will automatically set the XTZ internet connection to active? Something like if the ABC connection is down, the XYZ will supply internet connection right away.
Now I want to make a status subdomain on another server.
ibeat.org on one - status.ibeat.org on another.
I've edited the master zone on server one and added status.ibeat.org. and www.status.ibeat.org. ... and pointed it with A and CNAME to the other server and related IP...
I have also created the subdomain on the second server.
So my question is what should I do to get this working? This isn't!
I want to have a status link on the ibeat site ... and also:
... if server one with ibeat.org fails make it open status.ibeat.org?
Should be pretty simple - but can't get my head wrapped around it.
I have been searching and searching for a solution. We are currently using one single vps to host some of our clients. We are finding more and more that we need to have some redundancy.
I have looked at using DNS failover using RSYNC/mysql replication etc with two servers, but just dont like the idea.
I have also looked at hosts like imountain etc that use h-sphere. I dont like this setup because services are split onto single machines. For example mail is done on one single server, therefor if that server is down, mail is down.
What I am looking for:
I am trying to stay in a budget of 150/month or less.
I would like to get one of the two options here:
option 1: two vps's or dedi's that technically act as one(a true cluster) then on top of that is OS and control panel and done. This solution doesnt allow for whole datacenter outages, or network issues.
option 2: Two geographically placed vps or dedi's that are somehow either load balanced, or failover.
Ultimately our goal is to have high uptime, but we dont really have much server load.
Basically failover is ok as loads are always low anyway, but if we are paying big $$ it would be nice to have it load balanced.
Please let me know if my expectations are way to high or my price is way too low. I need to find a solution here somehow and if I cant find anything will most likely just go with DNS failover.
to do a standby fail over solution for a web server box. I would like the solution to be automated so that in the event of a failure the change happens without any manual intervention.
I have 2 identical hardware boxes and bandwidth is not an issue.
I want to setup a failover approach in which if after a particular timeout say 10secs the load shifts to some other website like Refer.com | The world. The timeout should be in Proxy Pass and if timeout occurs it shifts to Refer.com | The world
I currently own several servers: let's say sites on 3 of those servers rely on a website that sits on server 4
If server 4 goes offline, then servers 1 2 and 3 suffer a lack of usability. The website on server 4 is very small and fast, but receives several hundred thousand visits a day
I figured it would be a good idea to replicate that website on each of my servers, but I'm unsure about how to set up a good redundancy system..
Using several nameservers doesn't work as expected (visitors are randomly sent to one of the nameservers, in no particular order)
So, there is my example. I have two servers in different locations. First one is the main server with all the data and the second one has just simple notice like "We will be back soon".
Now, if I set the primary DNS server on main server and secondary DNS on second one (but with different A records), will users actually get the server two if main server is down?
Will this work or not? I want 100% access to the site, at least to the server with only notice (I don't need data from main server). I can set the round robin, but I don't need load balancing (actually I want access only main server), but just if main server is down to go on the second one.
We have a 1 server setup. Right now all dns, web, and email are hosted from this single box.
We wish to bring in a server2 and have dns cluster setup, this would also host mirrors of email and web sites from server1.
What i want to know is what is the best way to setup the DNS cluster/nameservers?
would it be
ns1.domain.com pointing to server1 dns ns2.domain.com pointing to server2 dns?
if that is the case and lets say server 2 goes down, wouldnt that mean the 50% of hits to the web site would be denied as ns2 is down? The reason i ask this is that to my understanding nameservers do not have priority, they are randomly hit.
I am trying to provide some small bit of redundacy.
I have a server which runs some important apps. I want to provide as much availability as I can..in case the server goes done, another one to take the load.
The server is a Win 2k3 one.
I've looked over the net but I don't know which solution should I go for: a Failover clusters or a Network Load Balancing setup.
I am trying to do a fail over solution with round robin dns. Our dns is served by windows and our web servers are setup with Linux..
I know round-robin does not by default do a fail over, however my understanding is that a script can be used to remove the failed server for dns, is anyone aware of something that will do this for windows?
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I run a site with about 1,000,000 unique visitors per month and recents server failures made me decide to get a failover server to minimize downtime. My goal wasn't to get 99.999% uptime but to be able to be back on track after a failure in a "reasonable" amount of time. After evaluating several solutions, I decided to go with DNS failover. Here's how the setup work:
1) mydomain.com points to main server with a very low TTL (time to live) 2) failover server replicates data from main server 3) when main server goes down, mydomain.com is changed to point to failover server
The drawback is the DNS propagation time since some DNS servers don't honor the TTL and there is some caching happening on the user's machine and browser. I looked for empirical data to gauge the extent of the problem but couldn't find any so I decided to setup my own experiment.
The Experiment ==============
I start with mydomain.com pointing to the main server with a TTL of 1800 seconds (1/2 hour). I then change it to point to the failover server which simply port forwards to the main server. On the main server, I periodically compute the percentage of requests coming from the failover server which gives me the percentage of people for which the DNS change has propagated.
I made the DNS change at exactly 16:04 on 06/21/06 and here are the percentage of propagated users:
So even after 18 hours, there is still a certain percentage of users going to the old server so DNS failover is obviously not a 99.999% uptime solution. However, since more than 90% of the users are propagated in the first hour, the solution works well enough for me.
