Re: Does Parallel Server Load Balance ?

From: Billy Shields <random_at_opera.iinet.net.au>
Date: 2000/03/13
Message-ID: <38cc9835$0$1928@motown.iinet.net.au>#1/1

nqaprjr_at_my-deja.com wrote:
: OPS by itself doesn't do load balancing. If you want load balancing you need
: to set up your TNSNames.ora file with a description list which contains your
: node information. One byproduct of using this configuration is that all
: users will connect to the surviving nodes if a node goes down. Downfalls are
: TNSPing will not work and when you connect you won't know which node your
: connected to unless you query v$parameter and check which thread you're
: using. Search your online Oracle documentation for "listener load balancing"
: for an example of how this is done.

Load balancing on OPS is somewhat at odds with the reasons for using OPS in the first place.

Say you have table A on a 2 node OPS site. If you use load balancing then both nodes will equally be accessing table A. As a result you will get a lot of pinging between the nodes as each node contends for access to this table.

Ideally if you have an n-node OPS site you want to (logically) partition your database into n equal size chunks (equal in terms of user load). These chunks should be fairly independant of each other. For instance, the Payroll department might access tables relating to employees, renumeration, benefits, etc whereas the Accounts department will access a different subset of tables. You then have Payroll access the database through Node 1 and the Accounts department access it from Node 2. If there isn't much crossover between the subsets of data each departmen tuses you'll get quite a lot of benefit from using OPS.

In this case you'd use failover rather than load balancing however. Eg this would be an entry from the tnsnames.ora file assuming an 8.1.x installation:

SOMEDB =
(DESCRIPTION =
(ADDRESS_LIST =

      (FAILOVER = ON)
      (ADDRESS = (PROTOCOL = TCP)(PORT = 1521)(HOST = 200.15.20.1))
      (ADDRESS = (PROTOCOL = TCP)(PORT = 1521)(HOST = 200.15.20.2))

    )
    (CONNECT_DATA =
      (SERVICE_NAME = somedb)
    )
  )

Hope that helps.

Regards
Billy Shields Received on Mon Mar 13 2000 - 00:00:00 CST