Re: Does this happen to you at work?
- From: stephen booth <stephenbooth.uk@xxxxxxxxx>
- To: davewendelken@xxxxxxxxxxxxx
- Date: Tue, 10 May 2005 21:38:57 +0100
On 5/10/05, david wendelken <davewendelken@xxxxxxxxxxxxx> wrote:
> Short of national security concerns, why would you want the extra overhea=
d of two additional database instances instead of just using three schemas =
in one instance?
Various reasons. The main ones are around mobility and political infightin=
g.
As separate instances if we need to move a database from one server to
another (say the server is overloaded so we need to move one of the
databases to a new server or one that's not so heavily loaded) then
it's just a case of copy the files over (or even just change some NFS
mounts) and we can bring it up on a new server. Change some network
settings and we're ready to go. Also if for some reason we need to
migrate one of the apps to a later version of Oracle but can't migrate
the others (maybe the vendors refuse to support the app for a later
version of Oracle, it's happened) then we can migrate the database
that needs migrating and leave the others as they are.
Political infighting is a bit more complex. Suppose we did have 3
different apps hosted int he same database. If we needed to schedule
an outage (say a reorg because we've added more disks) then we can
guarantee that no time within the next 12 months will be suitable for
all three. If the users of one app say next Thursday is OK then users
of one (or both) of the others will say that it can't be then because
they absolutely have to run a big batch job then and the whole
organisation will collapse around our ears if the database isn't
available. Indeed if one user team says that next Thursday is ideal
then one (or both) of the others will schedule a big batch job for
that day. With separate instances, assuming we don't need to down the
whole server and we're not applying a patch, we can shutdown each one
as and when we have the OK for an outage.
Stephen
--=20
It's better to ask a silly question than to make a silly assumption.
--
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