Re: Replication Options
- From: "Yechiel Adar" <adar76@xxxxxxxxxxxx>
- To: <Oracle-L@xxxxxxxxxxxxx>
- Date: Fri, 4 Feb 2005 11:11:33 +0200
The requirments for DR are totaly different from activ/activ replication.
We implement DR by the storage replication to remote site. On the remote
site we have another machine that is NOT connected to the storage but is
built with Oracle software and database defined on the disk on the storage.
In case that the primary site falls, you activate the second machine and it
uses the database that is on the remote site storage. The replication is
performed by the storage controller writing each block to both storage
arrays. This option can work fine up to not so remote site.
For active/active you need the machines close by with very high speed
connections between them, or the network time will bring the system to its
knees.
You need also to decide about syn or asyn replication. While syn replication
will cause less overhead it make you dependent on the second site to
continue working, asyn replication will cause a lot more overhead in the
database (Just think: insert the change into a locat queue, read it and send
it to the second machine and then delete it from the local queue).
It also depends on th updates to select ratio. On havily updated systems the
penalty will be much worse.
You did not specify what they are doing on the remote site, reporting only
or full update application. You did not say what is the distance between
them.
To have the users accessing the database from a remote site maybe you can
get by with the application running in the remote site and accessing the
database in the primary site, or using the web to run the application on the
primary site.
As you can see there are a lot of options that must be checked before
deciding wich way to go.
Wanting (active/active) and being ready to pay the penalty for this option
are two very different things.
Yechiel Adar
Mehish Computer Services
----- Original Message -----
From: <Rajesh.Rao@xxxxxxxxxxxx>
To: <Oracle-L@xxxxxxxxxxxxx>
Sent: Thursday, February 03, 2005 7:29 PM
Subject: Replication Options
> Hello All,
>
> We have an application that's presently on 9.2.0.5 on a Solaris 8 box. We
> are looking to have a DR / Standby site for this database at a remote
> location. Logical Standby database and Advanced replication were ruled out
> because of the use of LONG and LONG RAW datatypes, and the use of IOT's by
> the database. So, we decided on a physical standby database.
>
> But now, the requirements change, in that, the user wants a ACTIVE/ACTIVE
> configuration. In all sense, its a RAC database with nodes at different
> physical locations. I read, that 10g supports LONG and LONG RAW datatypes
> for Logical standby.
>
> My questions are:
> 1. Does Oracle support LONG datatypes with Advanced Replications in 10g?
> 2. What options do I have? Any third party applications? (Shareplex?)
>
> Thanks
> Raj
>
>
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