Stack Overflow
Stack Overflow

Questions tagged [high-availability]

High availability is a software design approach and implementation that ensures a prearranged level of operational performance will be met during a contractual measurement period.

Attributes of high availability (HA):

  • Maximum uptime
  • Online maintenance - With little or no service interruption.
  • Simplicity - Complexity is an enemy of reliability, and encourages operator error, and so it is best avoided (e.g., Does a particular use-case really require the burden of implementing HA?).

Approaches that increase availability:

  • Fault-tolerance: Duplicate services waiting to take over should the primary fail or become unreachable.
    • Active/Active +Enables load-balancing -More complicated
    • Active/Passive +Simpler -Does not increase load capacity.
  • Replication:
    • Synchronous +Safer -Slow over longer distances.
    • Asynchronous +Faster -Possibility of data loss
      • The "A" in CAP Theorem.
  • Graceful degradation: Rate limiting and client throttling.
1355 questions
11
votes
12 answers

Any command to get active namenode for nameservice in hadoop?

The command: hdfs haadmin -getServiceState machine-98 Works only if you know the machine name. Is there any command like: hdfs haadmin -getServiceState which can tell you the IP/hostname of the active namenode?
Dragonborn
  • 1,505
  • 1
  • 14
  • 32
11
votes
6 answers

Application upgrade in a high availability environment

I am writing a NoSQL database engine and I want to provide features to help the developers to upgrade their application to a new version without stopping the operation of the website, i.e 0% downtime during upgrade. So my question is, what are the…
Nulik
  • 4,803
  • 7
  • 36
  • 90
11
votes
3 answers

Spring Security and multiple ldap configuration

I use Spring Security to manage user and group securities. All datas are stored in a ldap server. My configuration is the following:
Jerome Cance
  • 7,769
  • 11
  • 49
  • 103
10
votes
4 answers

Stop accepting new TCP connections without dropping any existing ones

I have two servers listening on a TCP port behind a load balancer. The load balancer can detect if a TCP connection attempt from a client was unsuccessful and retry it to the second server without dropping that connection. I want to be able to bring…
John29
  • 2,830
  • 2
  • 27
  • 48
10
votes
4 answers

How do I run multiple spark applications in parallel in standalone master

Using Spark(1.6.1) standalone master, I need to run multiple applications on same spark master. All application submitted after first one, keep on holding 'WAIT' state always. I also observed, the one running holds all cores sum of workers. I…
Sankalp
  • 1,894
  • 5
  • 27
  • 37
10
votes
1 answer

Merging multiple identical Kafka Streams topics

I have 2 Kafka topics streaming the exact same content from different sources so I can have high availability in case one of the sources fails. I'm attempting to merge the 2 topics into 1 output topic using Kafka Streams 0.10.1.0 such that I don't…
Bogdan
  • 282
  • 8
  • 15
10
votes
3 answers

EC2 Amazon High Availability Always On

I am using a Web & DB Instances in AWS EC2 and I want to make them high available, so that if one server fails (primary server), then another one is turned on (secondary server). I have found lots of information for RDS high availability but not for…
Misha Zaslavsky
  • 4,808
  • 10
  • 44
  • 95
10
votes
1 answer

High Availability - What does Crossover mean in this context?

I'm working on a Mesos framework to run some jobs and it seems like a great opportunity to learn about making a highly available system. To that end, I'm doing some reading on distributed systems and I made the mistake of visiting wikipedia. The…
munk
  • 10,644
  • 4
  • 45
  • 67
9
votes
2 answers

Solr safe dataimport and core swap on high-traffic website

Hello fellow technicians, Let's assume we have a (PHP) website with millions of visitors a month and we running a SolR index on the website with 4 million documents hosted. Solr is running on 4 separate servers where one server is the master and…
Kees Schepers
  • 2,212
  • 1
  • 17
  • 31
9
votes
3 answers

How does Terracotta work in this situation?

So lets say I have an N sized server array set up like so: alt text http://www.terracotta.org/web/download/attachments/43909161/ServerArrayMirrorGroup.png I have a simple JavaBean/POJO: package example; public class Person { private OtherObject…
mainstringargs
  • 11,482
  • 33
  • 101
  • 163
9
votes
2 answers

Tomcat7 parallel deployment feature: experiences using it on production servers?

I've recently learned about Tomcat 7's feature to allow multiple versions of the same webapp deployed at the same…
trafalmadorian
  • 1,630
  • 1
  • 15
  • 20
9
votes
3 answers

High availability and scalable platform for Java/C++ on Solaris

I have an application that's a mix of Java and C++ on Solaris. The Java aspects of the code run the web UI and establish state on the devices that we're talking to, and the C++ code does the real-time crunching of data coming back from the devices.…
Andrew
  • 11,520
  • 12
  • 65
  • 82
9
votes
1 answer

Detecting and recovering failed H2 cluster nodes

After going through H2 developer guide I still don't understand how can I find out what cluster node(s) was/were failing and which database needs to be recovered in the event of temporary network failure. Let's consider the following scenario: H2…
Alex
  • 2,537
  • 3
  • 18
  • 24
9
votes
3 answers

Geo Redundancy in Azure Service Fabric Applications

I'm trying to come up with a solution for achieving Geo-Redundancy (2+ datacentres) while using Service Fabric reliable Actors/Services to manage state. It insinuates here that geo replication is possible This may happen when, for example, if you…
Alex Zevenbergen
  • 191
  • 1
  • 11
9
votes
2 answers

Hadoop 2.0 Name Node, Secondary Node and Checkpoint node for High Availability

After reading Apache Hadoop documentation , there is a small confusion in understanding responsibilities of secondary node & check point node I am clear on Namenode role and responsibilities: The NameNode stores modifications to the file system…
Ravindra babu
  • 42,401
  • 8
  • 208
  • 194
1 2
3
…
90 91