High availability is an architectural consideration often involving degrees of redundancy to insure availability in case of system or component failure.
42
votes
10answers
9k views
Multiple data centers and HTTP traffic: DNS Round Robin is the ONLY way to assure instant fail-over?
Multiple A records pointing to the same domain seem to be used almost exclusively to implement DNS Round Robin as a cheap load balancing technique.
The usual warning against DNS RR is that it is not ...
1
vote
2answers
1k views
Keepalived over GRE tunnel for failover on VPS environment
I'm running an application on Linode. Their network does not support multicasting. Many tools used for failover (keepalived, spread/wackamole, hearbeat) require multicast to work (as far as I know). ...
10
votes
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 ...
5
votes
4answers
3k views
SonicWall “gotchas”?
We're looking to move away from PFSense and CARP to a pair of SonicWall NSA 24001 configured in Active/Passive for High Availability.
I've never dealt with SonicWall before, so is there anything I ...
6
votes
5answers
2k views
How to perform cron jobs failover?
Using two Debian servers, I need to setup a strong failover environment for cron jobs that can be only called on one server at a time.
Moving a file in /etc/cron.d should do the trick, but is there ...
7
votes
4answers
6k views
Can Exchange 2010 high availability be achieved with only 2 servers?
In Exchange 2010, you can define Database Availability Groups and have your mailbox database(s) automatically replicated between multiple servers, and you can have mailbox server which are members of ...
2
votes
3answers
873 views
If DNS Failover is not recommended, what is?
As a followup question to his very popular question: Why is DNS failover not recommended?, I think it was agreed that DNS failover is not 100% reliable due to caching.
However the highest voted ...
2
votes
1answer
1k views
relation between heartbeat,openais,corosync
i am planning for high availability on lucid ubuntu, i started with drbd after a simple configuration on drbd I went to heartbeat and had a simple config on it too.
on drbd official site a document ...
0
votes
1answer
55 views
Office network failover? [duplicate]
Possible Duplicate:
What hardware do I need to add a backup internet connection?
I have a office LAN providing internet access to several workstations. Each workstation is basically ...
0
votes
3answers
310 views
Connecting Linux system to switch from 2 interfaces
To get proper redundancy, we've installed 2 switches in our network and connected them to eachother. We now want to hook our servers to both switches. Since all servers have 2 ethernet ports, this ...
8
votes
7answers
10k views
Alternatives to Heartbeat, Pacemaker and CoroSync?
Are there any major alternatives for automatic failover on Linux besides the typical Heartbeat/Pacemaker/CoroSync combinations? In particular, I'm setting up failover on EC2 instances, which only ...
7
votes
4answers
3k views
What exactly does Gluster do?
I've been playing with gluster for the last 2 days and been asking questions here and on their questions system.
I really don't understand some of the stuff. I see people saying stuff like
Set up ...
9
votes
5answers
442 views
High server availabilty for a small business
After having a bit of scare with a server that wouldn't come up one morning, the higher ups have decided that the business needs a high availability / fail over setup.
We have 5 main servers (4x ...
3
votes
1answer
2k views
Keepalived for more than 20 virtual addresses
I have set up keepalived on two Debian machines for high availability, but I've run into the maximum number of virtual IP's I can assign to my vrrp_instance. How would I go about configuring and ...
2
votes
2answers
1k views
Load balancing / Failover for multiple VPS's set across different datacenters
I know many variants of this question has been asked already, but I still can't find a good answer to my needs.
What I want to do is setup a few (2 at minimum) VPS's to host my web apps on. I'd like ...
2
votes
1answer
4k views
Heartbeat vs UCarp
Can anyone explain what is the major difference between Heartbeat and UCarp for IP fail-over scenarios?
They both seem to provide this functionality, perhaps UCarp simpler to set-up?
Thanks.
15
votes
5answers
813 views
When my A web server gets unplugged, how do I automatically redirect all the users to my B web server in another city, and vice versa?
When my A web server gets unplugged, how do I automatically redirect all the users to my B web server in another city, and vice versa?
A load-balancing switch does what I want, except I can't figure ...
10
votes
3answers
1k views
The downsides of using nginx as a primary web server?
I've seen millions of websites using nginx as a proxifying webserver working together with Apache. But I've seen very few servers running nginx only as their default webserver. What are the main ...
0
votes
2answers
1k views
HA web cluster setup
I'm setting up a highly available web cluster, I'm planning to start out with 2 web servers connected to shared storage (perhaps via NFS). What's the best way of implementing this? Should the web ...
2
votes
4answers
407 views
Solution for two-way file-system transparent solution
I need to implement some sort of HA setup where 2 servers need to be able to always be in sync, no matter on which one you write on.
The DB part can be covered by a master-master replication setup.
...
2
votes
2answers
507 views
Does my BIND zone really provide redundancy and load balancing?
We have the following IP addresses (for example):
1.1.1.1
2.2.2.2
Each hosts the same website, but on a different server. We want to do some really simple load balancing by having web users visit a ...
2
votes
1answer
669 views
Highly Available Web Application (LAMP)
I work for a small company who provides a web application for thousands of users. Earlier this year they had one server hosted one company. We recently acquired another server in a different location ...
2
votes
1answer
180 views
What database is easy to maintain and manage in a cluster?
I'm looking for a database (DBMS) that is easy to scale out. I would like to have high availability so I need a multi-master cluster, where the data is replicated to two or more physical computers. I ...
1
vote
1answer
93 views
Advantage of Microsoft Cluster over Microsoft Network Load Balancer
Till recently, I assumed that Microsoft NLB worked at an OS/Machine level rather than an Application Level. i.e. the NLB just monitors heartbeats on the machine to check if machine is alive and then ...
1
vote
1answer
2k views
My DAG has failed over, but Outlook clients won't connect
My company have two exchange 2010 server(Mail1 & Mail2) with DAG configuration. One day my Mail1 server down and the Mail2 auto take over! My question is now the end user can't access the mail2 ...
0
votes
2answers
286 views
Tools to manage sql 2008 database mirroring?
We are going to be moving about 20 databases that live on a single instance of sql 2000 to a sql 2008 r2 environment with database mirroring.
What I'm looking for is a tool or scripts that will help ...
3
votes
6answers
294 views
Wiki/CMS with synchronization? [closed]
We're looking into putting up a wiki or CMS for internal use by our IT department. One of the big things we want to use it for is disaster recovery procedures.
Given that a disaster, such as a ...
2
votes
2answers
1k views
Network load balancing, efficience and limits?
I'm about to study about NLB on Windows Server 2003. It archives both of my interests now: scalability and high-availability. But I don't know about its power in production environment.
Is NLB a ...
1
vote
3answers
269 views
MySQL HA Solutions
I am evaluating the options to build MySQL HA and found the below solutions
Percona XtraDB Cluster,
Tungsten Replicator, and
MySQL Cluster.
Could you please help me to choose the best one with ...
1
vote
1answer
587 views
MySQL cluster for Drupal?
We have a pretty busy site based on Drupal and I was thinking of introducing some form of clustering for HA and Load balancing.
However, http://drupal.org/requirements says: Drupal supports MyISAM ...
1
vote
6answers
789 views
Will the OS crash if the system partition can't be access for a short period?
An operating system is installed in a virtual machine environment, such as VMWare or KVM. A network shared disk volume (e.g., iSCSI disk) is used as the OS system partition. Heavy traffic is running ...
1
vote
4answers
432 views
Server CPU spikes suddenly and becomes unusuable - Tips to monitor/analyze this?
my server has been going down over the last 24-48 hours, CPU spikes from 15% to 100% and server becomes unusable and all my sites go down as a consequence of it.
Any tips on how I could track what is ...
-1
votes
2answers
533 views
Simple IP load balancer for web service that runs on Windows XP or Windows 7 Professional?
I've a closed code application that needs to connect to a web service that needs to run on XPs or Windows 7 (desktop). The application can only connect to a single IP address. The application is low ...
-2
votes
0answers
37 views
Conga cluster node-fencing problems [closed]
I have a three-node cluster created using Conga. Shutting down one node on which services are running gets fenced, but the services don't migrate to another node.
Here's our cluster.conf ...
