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From Russell Bradberry <>
Subject Re: EC2 SSD cluster costs
Date Tue, 19 Aug 2014 16:00:40 GMT
Short answer, it depends on your use-case.

We migrated to i2.xlarge nodes and saw an immediate increase in performance.  If you just
need plain ole raw disk space and don’t have a performance requirement to meet then the
m1 machines would work, or hell even SSD EBS volumes may work for you.  The problem we were
having is that we couldn’t fill the m1 machines because we needed to add more nodes for
performance.  Now we have much more power and just the right amount of disk space.

Basically saying, these are not apples-to-apples comparisons

On August 19, 2014 at 11:57:10 AM, Jeremy Jongsma ( wrote:

The latest consensus around the web for running Cassandra on EC2 seems to be "use new SSD
instances." I've not seen any mention of the elephant in the room - using the new SSD instances
significantly raises the cluster cost per TB. With Cassandra's strength being linear scalability
to many terabytes of data, it strikes me as odd that everyone is recommending such a large
storage cost hike almost without reservation.

Monthly cost comparison for a 100TB cluster (non-reserved instances):

m1.xlarge (2x420 non-SSD): $30,000 (120 nodes)
m3.xlarge (2x40 SSD): $250,000 (1250 nodes! Clearly not an option)
i2.xlarge (1x800 SSD): $76,000 (125 nodes)

Best case, the cost goes up 150%. How are others approaching these new instances? Have you
migrated and eaten the costs, or are you staying on previous generation until prices come
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