Michael,
Replication Manager is not needed to set up
replication, in fact I recommend doing everything via
the API calls until you fully understand replication.
Multi-master replication requires Enterprise Edition
for all replicated sites. 8.0 requires EE for
updatable snapshot sites, 8i supports updatable
snapshots on both Standard and EE.
You are correct that a standby db is not an option
given your current restrictions (O8 on Solaris 2.6 and
O8i on Redhat 6.1.) as standby db's require that both
the Oracle versions AND the OS be the same.
/*+ SOAPBOX ON */
I cannot stress enough the importance of having a
thorough understanding of replication BEFORE
designing, testing, and implementing a replication
environment. At minimum reading the replication
manuals, although I
*highly* recommend the training. IMHO replication is
one of the most complex features of the db to
implement and maintain. The GUI Replication Manager
tool is nice, but there's no substitute for knowing
the underlying API calls and it's a lot easier to make
things worse by clicking on the wrong button.
Some items that many people overlook:
- Conflict resolution (in a nutshell, if two or more
sites perform DML on the same row, whose change
wins"). Manually resolving ORA-1403 "no data found"
errors, which are almost always due to lack of
conflict resolution routines, is painful enough when
there's only two sites and a handful of errors. The
amount of pain increases exponentially in relation to
the number
of sites!
- The number of replication groups and the objects
contained in them. For example, whenever you need to
perform admin operations on a replicated object you
must suspend replication on the group to which it
belongs, which means that a) all tx's currently queued
at ALL sites must be pushed before replication can be
suspended; and b) while replication is
suspending/suspended DML operations cannot be
performed against the replicated tables in the
suspended group.
- Considering the pros and cons of ALL the different
types of replication before deciding which method to
use.
- Evaluating the network between all sites
bandwidth, latency, etc...).
- Is the application suited to replication? Ideally
the data that needs to be replicated should be
segregated from other data. Snapshot replication
in 8i allows you to replicate a subset of rows or
columns (with some restrictions); multi-master
replication requires you to replicate the entire
table.
- Load testing. Can the environment and network
handle the number of tx's that will be generated
during peak times (this is often directly related to
#'s 4 & 5)? Whatever you expect your peak load to be,
test it with 5x, 10x, or more, tx's to see if it can
still handle it (what happens if one or more sites are
down for an extended period of time and tx's back up -
how
long will it take for the system to catch up, if
ever?)? Can you afford the downtime needed for
offline instantiation if you can't push all the tx's?
- How will replication affect your disaster recovery
plans for all the sites? For example, how will you
get your replicated tables back in sync if you need to
perform PITR to one site? Hint: A robust conflict
resolution scheme is essential!
The following notes available on MetaLink will help
you get started with replication:
Note 50593.1 - "Before using Replication Manager with
v8.0"
The above note is useful regardless of whether you
intend to use Rep Mgr and applies to 8i as well
Note 62398.1 - "Creating a Replication Environment in
Oracle 8.0.X"
The above note applies to 8i as well
Note 76500.1 - "Creating An Updatable Snapshot
Environment in Oracle 8i"
/*+ SOAPBOX OFF */
HTH,
- Anita
--- Michael Johnson <mjohnson138_at_yahoo.com> wrote:
> Hi there,
>
> I'm running O8 on Solaris 2.6 and O8i on Redhat 6.1.
>
> I am trying to test out some replication but am
> having
> problems. Since I don't have OEM for Redhat, I
> can't
> run the replication manager. Is there a way I can
> replicate from Solaris to Redhat? Is there a secret
> executable that starts replication on Linux?
>
> Also, I'm looking at the standby database option but
>
> according to the Oracle docs they must be the same
> version of Oracle which wrecks this idea from the
> outset. Again, any ideas?
>
> Thanks.
>
> __________________________________________________
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> Author: Michael Johnson
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Received on Fri May 12 2000 - 09:46:29 CDT
