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From Ben Bromhead <...@instaclustr.com>
Subject Re: Recommendation for hosting multi tenant clusters
Date Wed, 14 Aug 2013 01:23:33 GMT
 http://www.mail-archive.com/user@cassandra.apache.org/msg11022.html sums it up pretty well.
Optimised images and provisioned IOPS may help, but whatever way you spin it your reads and
writes are still going out on the network somewhere.

EBS is like a giant SAN which will drop out at any second, take almost everything in your
region down with it whilst simultaneously opening up a gate to hell that lets all sorts of
unimaginable horrors into the world. 

Ok maybe not that bad, but network issues between ebs and your instances is painful. Whereas
network issues with a single AZ can be dealt with in the course of normal cluster operations.

On a slight tangent, have a read of http://thelastpickle.com/2011/06/13/Down-For-Me/ which
does an awesome job of explaining what will happen to your quorum reads and writes when a
AWS AZ goes down (and you use ephemeral storage).

Cheers

Ben Bromhead
Instaclustr | www.instaclustr.com | @instaclustr | +61 415 936 359


On 14/08/2013, at 10:42 AM, Jon Haddad <jon@jonhaddad.com> wrote:

> I strongly recommend against EBS, even with optimized & ebs provisioned.  The throughput
you'll get from local drives is significantly better than what you'll get with EBS (even 4K
iops provisioned)
> 
> On Aug 13, 2013, at 2:10 PM, Rahul Gupta <rgupta@dekaresearch.com> wrote:
> 
>> I am working on requirement to host multi tenant Cassandra cluster (or set of clusters)
on Amazon EC2 (AWS).
>>  
>> With everything else sorted out, I have below question where I am looking for recommendations:
>>  
>> Does Amazon’s recent support of EBS optimized images changes whole discussion around
EBS vs. ephemeral drives and image size?
>>  
>> ·         Option 1: reserved m1.xlarge (4x420GB drives) is $0.187/hr
>> ·         Option 2: reserved m1.large EBS-optimized  is $0.119/hr (~$50/month less
than m1.xlarge, but $168/month for 4x420 standard EBS volumes): costs $120/month more, but
additional recovery options
>>  
>> Given Cassandra is designed to survive failures, combining replication factor 3 and
backing-up to S3, I think should be enough for back up.
>>  
>> Please advise.
>>  
>> Thanks,
>> Rahul Gupta
>> DEKA Research & Development
>> 340 Commercial St  Manchester, NH  03101
>> P: 603.666.3908 extn. 6504 | C: 603.718.9676
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