some of my questions may not be related to this group however, I know that some 
of them are directly related to this list. 

first of all I would like to learn that, any of you use the postgresql within the 
clustered environment? Or, let me ask you the question, in different manner,
can we use postgresql in a cluster environment? If we can do what is the support
method of the postgresql for clusters? 

I would like to know two main clustering methods. (let us assume we use 2 machines 
in the clustering system) in the first case we have two machines running in a cluster
however, the second one does not run the database server untill the observation of the 
failure of the first machine, the oracle guys call this situation as active-passive 
configuration. There is only one machine running the database server at the same time. 
Hence, in the case of failure there are some time to be waited untill the second 
machine comes up.

In the second option both machines run the database server at the same time. Again 
supports this method using some additional applications called Real Application 
Cluster (RAC).
Again oracle guys call this method as active-active configuration.

The questions for this explanation are:
      1 - Can we use postgresql within clustered environment?
      2 - if the answer is yes, in which method can we use postgresql within a cluster?
      active - passive or active - active?

Now, the second question is related to the performance of the database. Assuming we 
have a 
dell's poweredge 6650 with 4 x 2.8 Ghz Xeon processors having 2 MB of cache for each, 
with the 
main memory of lets say 32 GB. We can either use a small SAN from EMC or we can put 
all disks 
into the machines with the required raid confiuration.

We will install RedHat Advanced Server 2.1 to the machine as the operating system and 
postgresql as 
the database server. We have a database having 25 millions records  having the length 
of 250 bytes 
on average for each record. And there are 1000 operators accessing the database 
concurrently. The main 
operation on the database (about 95%) is select rather than insert, so do you have any 
idea about 
the performance of the system? 

best regards,


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