Re: Which RBS is my Update using ?

"Daniel Morgan" <dmorgan_at_exesolutions.com> wrote in message news:3D8E4E10.8AAABEFC_at_exesolutions.com...
> Paul Brewer wrote:
>
> > "Daniel Morgan" <dmorgan_at_exesolutions.com> wrote in message
> > news:3D88D674.1619D215_at_exesolutions.com...
> > > Tanel Poder wrote:
> > >
> > > > Hello,
> > > >
> > > > > What you are missing ... is that rollback segments need to be able
to
> > expand to
> > > > > handle the largest transaction on the system. That is not the same
as
> > saying they
> > > > > need to permanently be large enough to handle the largest
transaction
> > on the
> > > > > system.
> > > >
> > > > I still don't see why rollback segments in my configuration are less
> > > > expandable than "They should all be identical and sized to handle
the
> > > > largest transaction on the system" configuration which you posted
> > > > yesterday..
> > > >
> > > > But about the cheap price of disk v.s. administration work cost, I
agree
> > > > with you.
> > > >
> > > > Thank you for your time,
> > > > Tanel.
> > >
> > > I'm not sure I understand your question. Rollback segments expand. And
> > expand until
> > > they either hit the maximum allowed extents parameter or run out of
disk
> > space. So as
> > > long as any rollback segment can expand enough to hold any transaction
> > which rollback
> > > segment becomes irrelevant.
> > >
> > > If you try to force a transaction into a specific rollback segment.
And
> > for any reason
> > > that specific segment is unavailable. The transaction will fail.
> > >
> > > Daniel Morgan
> > >
> >
> > OK, I'll rise to this one.
> >
> > Our organisation runs Peoplesoft in Atlanta.
> > Each morning at 3 a.m. we replicate about 80 of the Peopleshit tables
back
> > to the U.K., then sort them out into something like a rational structure
for
> > reporting purposes.
> > So, during the day, the U.K. tables are read only, and we don't need
much by
> > way of rollback segments. However, during the actual replication process
we
> > need to use a segment ROLL_BIG, so that the entire refresh group will
either
> > succeed or fail.
> >
> > Paul
>
> And your point is? ;-)
>
> All I said was make all of your rollback segments capable of expanding to
be as
> large as ROLL_BIG. The cost of doing this is zero.
>
> Smaller transactions won't ever expand beyond whatever transactions they
> receive. But if they do end up being the rollback segment chosen for the
nightly
> process ... they will not fail. Right now you have a single point of
failure.
>
> Daniel Morgan
>

Daniel,

ROLL_BIG is offline during the day. The nightly session brings it online, does 'set transaction use rollback segment ROLL_BIG', does its work, then takes it offline again.
The other rollback segments are all equally sized (and much smaller). What's wrong with that?

Regards,
Paul Received on Mon Sep 23 2002 - 16:00:37 CDT