Database Reference
In-Depth Information
the master node goes down. Such database architectures are discouraged where high
availability of data is a priority. NoSQL distributed databases generally prefer multiple
master/slave configuration or peer-to-peer architecture to avoid a single point of fail-
ure. Cassandra delivers peer-to-peer architecture where each Cassandra node would
have an identical configuration. We will discuss this at length in the coming chapters.
Figure 1-3a depicts a system single master acting as single point of contact to re-
trieve data from slave nodes. If the master goes down, it would bring the whole system
to a halt until the master node is reinstated. But with multiple master configurations,
like the one in Figure 1-3b , a single point of failure does not interrupt service.
Figure 1-3 . Centralized vs. distributed architecural setup
High Availability
High availability clusters suggest the database is available with 24x7 support with min-
imal (or no) downtime. In such clusters, data is replicated across multiple nodes, in
case one node is down still another node is available to serve the read/write requests
until that node is up and running. Cassandra's peer-to-peer architecture ensures high
availability of data with co-location.
Identifying the Big Data Problem
Recently, it has been observed that developers are opting for NoSQL databases as an
alternative to RDBMS. However, I recommend that you perform an in-depth analysis
before deciding on NoSQL technologies. Traditional RDBMS does offer lots of fea-
 
 
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