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From Baskar Duraikannu <>
Subject RE: Cassandra on Ceph
Date Sun, 01 Feb 2015 12:09:43 GMT
What is the reason for running Cassandra on Ceph? I have both running in my environment but
doing different things - Cassandra as transactional store and Ceph as block storage for storing
From: Jan<>
Sent: ‎2/‎1/‎2015 2:53 AM
Subject: Re: Cassandra on Ceph

Ceph is a block based storage architecture based on RADOS.    It comes with its own replication
& rebalancing along with a map of the storage layer.
Some more details & similarities: a)Ceph stores a client’s data as objects within storage
pools.   (think of C* partitions)b) Using the CRUSH algorithm, Ceph calculates which placement
group should contain the object, (C* primary keys & vnode data distribution) c) and further
calculates which Ceph OSD Daemon should store the placement group   (C* node locality) d)
The CRUSH algorithm enables the Ceph Storage Cluster to scale, rebalance, and recover dynamically
(C* big table storage architecture).
C*  comes with everything that Ceph provides (with the exception of block storage).      There
is no value add that Ceph brings to the table that C* does not already provide. I seriously
doubt if C* could even work out of the box with yet another level of replication & rebalancing.
Hope this helpsJan/
C* Architect

     On Saturday, January 31, 2015 7:28 PM, Colin Taylor <> wrote:

 I may be forced to run Cassandra on top of Ceph. Does anyone have experience / tips with
this. Or alternatively, strong reasons why this won't work.

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