Re: Replicating Live Oracle DataFiles/LUNs to remote site via SAN tool?

  • From: Tanel Poder <tanel@xxxxxxxxxx>
  • To: Richard.Goulet@xxxxxxxxxxx
  • Date: Thu, 27 Aug 2009 23:52:30 +0800

With storage level replication, corruptions coming from Oracle/OS software
or host/HBA hardware get replicated to DR site. With Data Guard, many
corruptions in redo stream would be detected and not propagated to DR
database, thanks to checksums and sanity checks.

Also, human errors, such accidential datafile deletion, overwriting or
formatting wrong device etc get replicated without a question and ability to
roll it back.

In my mind the biggest benefit of storage level replication would be that
you can offload most of your replication to OS/Storage team, without having
to come up with different strategy for each database/application in house.

But for Oracle purposes I prefer data guard due all the extra flexibility.

Tanel Poder

On Thu, Aug 27, 2009 at 11:05 PM, Goulet, Richard <
Richard.Goulet@xxxxxxxxxxx> wrote:

>  Chris,
>     Pros:
>          1) For you it's extremely easy to set up.  You just sit back and
> watch the Unix admin do all of the work. I like that.
>          2) If there is a problem with the solution your not on the carpet
> for it.
>          3) If and when you upgrade of patch the remote system gets the
> update as well, less work.  Assuming that ORACLE_HOME is replicated as well.
>     Cons:
>         1) If the DR database doesn't start for any reason you know who's
> to blame.  You of course.
>         2) If your database expands onto new luns they may or may not be
> included in the replication works.
>         3) Adding a new lun in some products requires downtime because you
> have to rebuild the remote system.
>         4) You need a LARGE network pipe between the sites and it HAS to
> be reliable.
>         5) If you do have a network issue between the sites your database
> can hang because the replication software is bogged down.  Not likely to
> occur immediately or in the event of a short outage, but longer outages will
> get there sooner or later.
>     As for expense, yes these solutions are expensive.  There's the cost
> of two identical SANs, the network connection, and the software.  But Oracle
> EE isn't a drop in the bucket either.  On the other hand if you've already
> got EE then replicating via Data Guard  may be more cost effective,
> especially if your not using the standby database as a reporting instance
> and the network pipe isn't large or reliable.

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