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From Les Hazlewood <...@katasoft.com>
Subject Re: 99.999% uptime - Operations Best Practices?
Date Thu, 23 Jun 2011 17:56:14 GMT
On Thu, Jun 23, 2011 at 5:59 AM, Dominic Williams
<dwilliams@system7.co.uk>wrote:

> Cassandra is a good system, but it has not reached version 1.0 yet, nor has
> HBase etc. It is cutting edge technology and therefore in practice you are
> unlikely to achieve five nines immediately - even if in theory with perfect
> planning, perfect administration and so on, this should be achievable even
> now.
>

Yep, this is a totally fair (and appreciated) point.


>
> The reasons you might choose Cassandra are:-
> 1. New more flexible data model that may increase developer productivity
> and lead to fast release cycle
>

Do you mean new to the developer?  Or a new feature in Cassandra (e.g.
something added to 0.8 for example)?


> 2. Superior capability as concerns being able to *write* large volumes of
> data, which is incredibly useful in many applications
>

Yep, this is obviously valuable for data crunching, analytics, reporting,
etc.  But how often is Cassandra used in 'read mostly' use cases?


> 3. Horizontal scalability, where you can add nodes rather than buying
> bigger machines
> 4. Data redundancy, which means you have a kind of live backup going on a
> bit like RAID - we use replication factor 3 for example
> 5. Due to the redundancy of data across the cluster, the ability to perform
> rolling restarts to administer and upgrade your nodes while the cluster
> continues to run (yes, this is the feature that in theory allows for
> continual operation, but in practice until we reach 1.0 I don't think five
> nines of uptime is always possible in every scenario yet because of
> deficiencies that may present themselves unexpectedly)
>

Is there a roadmap or time to 1.0?  Even a ballpark time (e.g next year 3rd
quarter, end of year, etc) would be great as it would help me understand
where it may lie in relation to my production rollout.


> 6. The benefit of building your new product on a platform designed to solve
> many modern computing challenges that will give you a better upgrade path
> e.g. for example in future when you grow you won't have to change over from
> SQL to NoSQL because you're already on it!
>

Indeed, this is why we're evaluating Cassandra and a small number of others.

To this end, how often to people use Cassandra today as their primary
(only?) data store as a full replacement for MySQL/Oracle/Postgres?  I
understand there are many use cases to use Cassandra in special cases and in
addition to a SQL data store.  But is it used frequently enough as a total
replacement?

There's no right/wrong answer for me - I'm just trying to get a feel for the
"we use it a lot for data mining and analytics and for 25% of our OLTP
needs" vs "we use it for all of our app's primary needs".  I'm just curious.

Thoughts?

Thanks!

Les

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