I'd like to start a separate thread on this issue.

Based on the feature request thread, there were some folks requesting
better functionality of ER in an HA solution. I'd like some feedback
on that.

1) Why is ER being used for HA instead of HDR?

2) What specific functionality is being requested on ER?


I realize that quite a few folks prefer usage of ER over HDR because
the secondary server can be more than a read-only server, a sub-set of
the main server, or on a different platform. However, HDR will always
be much easier to set up and ER does not support a synchronous mode of
replication.

But I would like to get a bit of feedback on this topic so I can
better understand why ER is being used and what the perceived pain
points are with HDR.

Thanks
M.P.

mpruet wrote:
>
> I'd like to start a separate thread on this issue.
>
> Based on the feature request thread, there were some folks requesting
> better functionality of ER in an HA solution. I'd like some feedback
> on that.
>
> 1) Why is ER being used for HA instead of HDR?
>
> 2) What specific functionality is being requested on ER?
>
> I realize that quite a few folks prefer usage of ER over HDR because
> the secondary server can be more than a read-only server, a sub-set of
> the main server, or on a different platform. However, HDR will always
> be much easier to set up and ER does not support a synchronous mode of
> replication.
>
> But I would like to get a bit of feedback on this topic so I can
> better understand why ER is being used and what the perceived pain
> points are with HDR.
>
> Thanks
> M.P.

We 'd like to ask for better alarming when ER cant cope with the
workload anymore.

Also we think that there should be an easy onstat command to see
how full mem queues are and if you are already spooling out to
disk etc.

In short: I'd like to see a onperf tool for ER diagnosis and
monitoring much like the onperf query tool does it for scans & joins

dic_k
--
Richard Kofler
SOLID STATE EDV
Dienstleistungen GmbH
Vienna/Austria/Europe

Several reasons to want an HA featured ER instead of HDR:

- Live instantly available backup, no recovery delay
- Live read/write accessible backup(s) (we prefer to run 10-25% of
production on backup servers so we know everything is working BEFORE
the primary fails. Conflicts are prevented by isolating accounts to a
single server.)
- Multiple backup servers so that:
- Even after failure you still have a failover option
- One server may not be able to handle the load but two can so
if there are four servers initially you can have two fail and
still continue with full service levels

Art S. Kagel

mpruet wrote:

> I'd like to start a separate thread on this issue.
>
> Based on the feature request thread, there were some folks requesting
> better functionality of ER in an HA solution. I'd like some feedback
> on that.
>
> 1) Why is ER being used for HA instead of HDR?
>
> 2) What specific functionality is being requested on ER?
>
>
> I realize that quite a few folks prefer usage of ER over HDR because
> the secondary server can be more than a read-only server, a sub-set of
> the main server, or on a different platform. However, HDR will always
> be much easier to set up and ER does not support a synchronous mode of
> replication.
>
> But I would like to get a bit of feedback on this topic so I can
> better understand why ER is being used and what the perceived pain
> points are with HDR.
>
> Thanks
> M.P.

Thanks,

I understand the reasons, but do they weigh more heavily than the latency
and set up issues?

We can get the data to the target server fairly quickly, but will not be
able to ensure that there won't be transactions in limbo in the event of a
failure. We probably won't ever be able to guarantee that degree of service
without going the two-phase commit route with distributed queries. That
would greatly impact the user application and is something that we've been
avoiding.

M.P.
"Art S. Kagel" <kagel@erols.com> wrote in message
news:40338282.6080005@erols.com...
> Several reasons to want an HA featured ER instead of HDR:
>
> - Live instantly available backup, no recovery delay
> - Live read/write accessible backup(s) (we prefer to run 10-25% of
> production on backup servers so we know everything is working BEFORE
> the primary fails. Conflicts are prevented by isolating accounts to a
> single server.)
> - Multiple backup servers so that:
> - Even after failure you still have a failover option
> - One server may not be able to handle the load but two can so
> if there are four servers initially you can have two fail and
> still continue with full service levels
>
> Art S. Kagel
>
> mpruet wrote:
>
> > I'd like to start a separate thread on this issue.
> >
> > Based on the feature request thread, there were some folks requesting
> > better functionality of ER in an HA solution. I'd like some feedback
> > on that.
> >
> > 1) Why is ER being used for HA instead of HDR?
> >
> > 2) What specific functionality is being requested on ER?
> >
> >
> > I realize that quite a few folks prefer usage of ER over HDR because
> > the secondary server can be more than a read-only server, a sub-set of
> > the main server, or on a different platform. However, HDR will always
> > be much easier to set up and ER does not support a synchronous mode of
> > replication.
> >
> > But I would like to get a bit of feedback on this topic so I can
> > better understand why ER is being used and what the perceived pain
> > points are with HDR.
> >
> > Thanks
> > M.P.
>