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From Vladimir Yudovin <vla...@winguzone.com>
Subject Re: single instance failover
Date Tue, 22 Nov 2016 19:56:46 GMT
Sorry, probably I didn't catch your setup fully.



Would you like to use shared data folder for both nodes, assuming you never run two Cassandra
process simultaneously?

Well, I guess it's possible. Running two Cassandra instances on the same data folder together
won't work, so prevent this situation, may be with some sort of file locking.



&gt;multinode Cassandra for Node B is not free

Sure, but besides higher reliability you also get increase in read queries speed (with consistency
ONE).



Best regards, Vladimir Yudovin, 

Winguzone - Cloud Cassandra Hosting, Zero production time






---- On Tue, 22 Nov 2016 14:28:33 -0500Lou DeGenaro &lt;lou.degenaro@gmail.com&gt;
wrote ----




Yes, change rpc_address to node B.


Immutability aside, if Node A Cassandra and Node B Cassandra are using the same directory
on the same shared filesystem, let's call it /cassandra/state/database, would that not be
a problem?  Or said differently, does not Node A need its own writable place /cassandra/state/database/nodeA
and likewise /cassandra/state/database/nodeB for Node B's writable place?



Multinode Cassandra may not always be available due to resource constraints.  Presumably multinode
Cassandra for Node B is not free: it takes up network, cpu, and replicated disk space, no?


Lou.



On 2016-11-22 11:10 (-0500), Vladimir Yudovin &lt;v...@winguzone.com&gt; wrote: 

&gt; Hi Lou,&gt; 

&gt; 

&gt; 

&gt; 

&gt; do you mean you set rpc_address (or broadcast_rpc_address) to Node_B_IP on second
machine?&gt; 

&gt; 

&gt; 

&gt; 

&gt; &amp;gt;there would be potential database corruption, no?&gt; 

&gt; 

&gt; Well, so SSTables are immutable, it can lead to unpredictable behavior, I guess.
I don't believe anybody tested such setup before.&gt; 

&gt; 

&gt; 

&gt; 

&gt; &amp;gt;Is there any guidance on single instance failover?&gt; 

&gt; 

&gt; I never saw one, the main Casandra idea that you build multinode cluster.&gt;


&gt;%










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