FreeLists / oracle-l / RE: RAC - Is it wise/ok/possible to run multiple databases across the same cluster?

[Job Miller <jobmiller@xxxxxxxxx>]

what are the demands that drive the requirement for multiple databases in the 
same cluster vs. a single larger database using the resources of the cluster?  
   
  for those that have multiples in the same cluster, does each db have its own 
shared home, are all the dbs on a particular node using the same local home, or 
does each db on each node have its own local home?
   
  I have heard cases where folks divide up nodes to form a set of smaller 
clusters, where each cluster runs a separate db. In this scenario each box has 
a single db on it (traditional best practice), and any box could be repurposed 
to join any other cluster at any time it as needed.  That assumes you have 
enough boxes.  If you are running 7 dbs in a 3 node cluster, it obviously 
doesn't work.
   
  Job
   
   


"Mark W. Farnham" <mwf@xxxxxxxx> wrote:        v\:* 
{behavior:url(#default#VML);}  o\:* {behavior:url(#default#VML);}  w\:* 
{behavior:url(#default#VML);}  .shape {behavior:url(#default#VML);}             
   IF you?ve got the shared disks for all the databases ?zoned? for access by 
all the hosts (machines) and sufficient interconnect bandwidth amongst the 
machines, then it is really just a question of gracefully starting and stopping 
the relevant instances of the databases on the various machines.
   
  Automating all this to dynamically adapt to load spikes would be one of the 
many conflicting definitions of ?grid.? Doing it ?by hand? at predefined 
workshifts should be reasonably manageable. You *might* want to avoid actually 
shutting down the non-prime-shift instances on C & D and just make it 
impossible to open a session on them if memory is not an issue on the C & D 
hosts. That depends on issues like pre-warming the cache, ?kept? lookup tables 
and packages, etc. versus the resource cost of keeping the idle instances up 
and checking them for blocks (which should approach zero cost as the length of 
idleness increases).
   
  Don?t confuse my statement that it should be possible with the idea that this 
is the best architecture for a given system.
   
  Regards,
   
  mwf
   
      
---------------------------------
  
  From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On 
Behalf Of Ethan Post
Sent: Monday, April 30, 2007 3:52 PM
To: Kerber, Andrew W.
Cc: oracle-l
Subject: Re: RAC - Is it wise/ok/possible to run multiple databases across the 
same cluster?

   
  OK, I had heard that perhaps there are issues because of the interconnect 
uses UDP. The goal would is to for example allow say 3 databases access to 
machines A & B during the day, while another database has exclusive access to C 
& D, then at night allow one of the first three databases to access A, B, C & 
D. 
    On 4/30/07, Kerber, Andrew W. <Andrew.Kerber@xxxxxxx> wrote:
      None that are different than any other requirements.  You don't even have 
to cluster all the instances.
     
  -----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto: oracle-l-bounce@xxxxxxxxxxxxx] On 
Behalf Of Ethan Post
Sent: Monday, April 30, 2007 2:19 PM
To: oracle-l
Subject: RAC - Is it wise/ok/possible to run multiple databases across the same 
cluster?
   
  Are there any technical limitations in regards to running multiple databases 
across the same set of servers in the same cluster







       
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