Re: HA solution

On 01/14/11 9:47 PM, Jaiswal Dhaval Sudhirkumar wrote:
>
> Hi,
>
> I am looking for active-active clustering solution.
>

best of luck.    active-active is fraught with complex hard-to-solve 
problems.



> I have one SAN box and two separate NODES, where I need to create 
> active-active cluster. My data directory would be one and mounted to 
> the SAN box for both the nodes. (There will be one sharable data 
> directory for both the nodes) So the query which will come to the load 
> balancer (pgpool) it will route to the node which has a less load. 
> However, it will use the same data directory. It is nothing but the 
> RAC kind of structure.  Now, my question is.
>
> 1)      Is it possible above implementation in PostgreSQL?
>

No

> 2)      Has someone implemented cluster in their production environment?
>

Oracle RAC supports configurations like that, however in our limited 
testing, we came to the conclusion that you needed at least 4 nodes 
before it was faster than 1 simple database server.   And of course, 
these 4 nodes required 4 times the Oracle licensing, which can get 
really expensive really fast.



Postgres can scale very nicely vertically with the right hardware (lots 
of CPU cores, lots of memory, lots of IO bandwidth).    The standard 
database server configuration for the hardware you described is an 
active/standby cluster, where all requests are processed by the active 
server, and the standby server only takes over if the active server has 
failed.