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10

There's no such thing as zero downtime. Set a realistic goal (say, five nines uptime), and plan around that. If you beat your target, great, but promising a system will never, ever go down can trap you in a state where it's impossible to make major architectural upgrades necessary to continue maintaining the system at reasonable expense.


9

Thoughts: If you are asking these question on a public forum, hire experts to do it for you Consider Postgres and SQL Server which will scale to this volume too Do you need ACID? No = consider NoSQL Design and hardware matter more than the platform Don't virtualise or cut other hardware corners What is your RPO/RTO? Maintenance window? a.k.a are you really ...


3

It is required during the installation and upgrade procedure when using the wizard in the Cloudera Manager. During normal cluster operation it is not needed. All communication is done via the locally running agents then. In fact Cloudera Manager does not store the credentials, after the installation / upgrade it will delete it. When you upgrade your ...


2

Looks like I had mistakenly set fs.default.name to 9000. Changed it to 8020, now everything works fine. Thanks to mgorven for the help!


2

The main consideration for zero (or close to) downtime is the amount of update activity. Updates (and deletes) conflict in ways that inserts don't. Level 1. Database is pretty much totally read only (eg used for a Content Management System). This is the easiest to replicate. Level 2. Only Inserts on a single node which get distributed to other 'read-only' ...


1

The easiest way to achieve an active/active configuration in Oracle is by using Oracle RAC (Real Application Cluster). RAC Documentation can be found here. RAC can also be combined with other Oracle High Availability tools like Data Guard or Streams. HA Documentation is available here. Keep in mind that some maintenance operation can require you to shut ...


1

I'd say it is possible to achieve zero downtime. GoldenGate tries to provide this solution with bi-directional replication. You'll still need conflict resolution for an active-active configuration, and yes it can become a problem, but it's a pretty good solution. For master/slave ChronicDB can do live updates accounting for replication without ...


1

This isn't necessarily a serverfault question. Being able to run two active databases in parallel will depend on your application code. The trick is you must design you code so there will never be a conflict with records simultaneously changed in both locations. A few design ideas: Use SYS_GUID to create all your primary keys instead of a sequence which ...


1

From the comments - this problem was caused because zookeeper was not running.


1

People usually use the Hadoop framework to process data coming out of scribe. You can use PHP to script map/reduce steps... However, unless you have a lot of data, this is probably going to be a lot of work for a small benefit: http://hadoop.apache.org/ Good luck with that !


1

The answer is hadoop-0.20.205.0 but you also need to replace jar files in ./lib/ of HBase with the ones of your working HDFS installation. For me it was: rm /opt/hbase-0.90.4/lib/hadoop-core-0.20-append-r1056497.jar cp /opt/hadoop-0.20.205.0/hadoop-core-0.20.205.0.jar /opt/hbase-0.90.4/lib/ cp /opt/hadoop-0.20.205.0/commons-configuration-1.6.jar ...


1

According to this documentation the /usr/lib/hbase/conf/hbase-site.xml file needs to be configured as follows: <configuration> <property> <name>hbase.cluster.distributed</name> <value>true</value> </property> </configuration> to avoid HBase manages its own ZooKeeper. After configuring this, the ...



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