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From "Vegard Berget" <>
Subject Re: Why don't you start off with a “single & small” Cassandra server as you usually do it with MySQL?
Date Wed, 18 Sep 2013 15:31:37 GMT
The idea behind Cassandra is not the same as for MySQL.  First of all
you can't get fault tolerance with one node.  I don't think Cassandra
nodes are more prone to be unavailable, but by using replication you
can get more availability right away.  If you have multiple instances
when you start out, you have the right configuration when things get
too large for one node.  Then there is the issue that Cassandra is
often used with very large data or very high traffic, to which it
scales very well.  If you don't expect to ever scale beyond one node
(because traffic will never be high, you will never have much data or
you never need the extra availability) then you of course could use
one single node without lots of RAM, but it _could_ also be that *SQL
is a better option?  
If you are a startup with great plans but no money and not much
data/traffic (yet:), or just want to test Cassandra, then I still
would suggest >1 nodes (3?), and instead reduce RAM and/or CPU to get
the right price.  In that case you could try to use  Tomcat on one
of the nodes.  This way you can see and test what Cassandra does
really well.  It is not really that Cassandra demands more than other
databases, but more that the problems it is designed to solve demands
more than some other problems.  FYI, I use 2-3 nodes with 2gb RAM
each for testing, and have never had any problems with that.  
----- Original Message -----
Sent:Wed, 18 Sep 2013 19:04:27 +0530
Subject:Why don't you start off with a “single & small” Cassandra
server as you usually do it with MySQL?

	 For any website just starting out, the load initially is minimal &
grows with a slow pace initially. People usually start with their
MySQL based sites with a single server(***that too a VPS not a
dedicated server) running as both app server as well as DB server &
usually get too far with this setup & only as they feel the need they
separate the DB from the app server giving it a separate VPS server.
This is what a start up expects the things to be while planning about
resources procurement. 

	 But so far what I have seen, it's something very different with
Cassandra. People usually recommend starting out with atleast a 3 node
cluster, (on dedicated servers) with lots & lots of RAM. 4GB or 8GB
RAM is what they suggest to start with. So is it that Cassandra
requires more hardware resources in comparison to MySQL, for a website
to deliver similar performance, serve similar load/ traffic & same
amount of data. I understand about higher storage requirements of
Cassandra due to replication but what about other hardware resources ?

	 Can't we start off with Cassandra based apps just like MySQL.
Starting with 1 or 2 VPS & adding more whenever there's a need ? 

	 I don't want to compare apples with oranges. I just want to know how
much more dangerous situation I may be in when I start out with a
single node VPS based cassandra installation Vs a single node VPS
based MySQL installation. Difference between these two situations. Are
cassandra servers more prone to be unavailable than MySQL servers ?
What is bad if I put tomcat too along with Cassandra as people use
LAMP stack on single server. 


	 _This question is also posted at StackOverflow here [1] & has an
open bounty worth +50 rep._  


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