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From Anuj Wadehra <anujw_2...@yahoo.co.in>
Subject Re: Production with Single Node
Date Sat, 23 Jan 2016 05:10:49 GMT
And I think in a 3 node cluster, RAID 0 would do the job instead of RAID 5 . So you will need
less storage to get same disk space. But you will get protection against disk failures and
infact entire node failure.
Anuj

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  On Sat, 23 Jan, 2016 at 10:30 am, Anuj Wadehra<anujw_2003@yahoo.co.in> wrote:   I
think Jonathan said it earlier. You may be happy with the performance for now as you are using
the same commitlog settings that you use in large clusters. Test the new setting recommended
so that you know the real picture. Or be prepared to lose some data in case of failure.
Other than durability, you single node cluster would be Single Point of Failure for your site.
RAID 5 will only protect you against a disk failure. But a server may be down for other reasons
too. Question is :Are you ok with site going down?
I would suggest you to use hardware with smaller configuration to save on cost for smaller
sites and go ahead with a 3 node minimum.That ways you will provide all the good features
of your design irrespective of the site. Cassandra is known to work on commodity servers too. 


ThanksAnuj



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  On Sat, 23 Jan, 2016 at 4:23 am, Jack Krupansky<jack.krupansky@gmail.com> wrote: 
 You do of course have the simple technical matters, most of which need to be addressed with
a proof of concept implementation, related to memory, storage, latency, and throughput. I
mean, with a scaled cluster you can always add nodes to increase capacity and throughput,
and reduce latency, but with a single node you have limited flexibility.
Just to be clear, Cassandra is still not recommended for "fat nodes" - even if you can fit
tons of data on the node, you may not have the computes to satisfy throughput and latency
requirements. And if you don't have enough system memory the amount of storage is irrelevant.
Back to my original question:How much data (rows, columns), what kind of load pattern (heavy
write, heavy update, heavy query), and what types of queries (primary key-only, slices, filtering,
secondary indexes, etc.)?

I do recall a customer who ran into problems because they had SSD but only a very limited
amount so they were running out of storage. Having enough system memory for file system caching
and offheap data is important as well.

-- Jack Krupansky
On Fri, Jan 22, 2016 at 5:07 PM, John Lammers <john.lammers@karoshealth.com> wrote:

Thanks for your response Jack.
We are already sold on distributed databases, HA and scaling.  We just have some small deployments
coming up where there's no money for servers to run multiple Cassandra nodes.
So, aside from the lack of HA, I'm asking if a single Cassandra node would be viable in a
production environment.  (There would be RAID 5 and the RAID controller cache is backed by
flash memory).
I'm asking because I'm concerned about using Cassandra in a way that it's not designed for. 
That to me is the unsettling aspect.
If this is a bad idea, give me the ammo I need to shoot it down.  I need specific technical
reasons.
Thanks!
--John
On Fri, Jan 22, 2016 at 4:47 PM, Jack Krupansky <jack.krupansky@gmail.com> wrote:

Is single-node Cassandra has the performance (and capacity) you need and the NoSQL data model
and API are sufficient for your app, and your dev and ops and support teams are already familiar
with and committed to Cassandra, and you don't need HA or scaling, then it sounds like you
are set.
You asked about risks, and normally lack of HA and scaling are unacceptable risks when people
are looking at distributed databases.
Most people on this list are dedicated to and passionate about distributed databases, HA,
and scaling, so it is distinctly unsettling when somebody comes along who isn't interested
in and committed to those same three qualities. But if single-node happens to work for you,
then that's great.
-- Jack Krupansky



  
  

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