IDS Forum

Re: HDR Primary and Secondary on different Version

Posted By: Martin Fuerderer
Date: Tuesday, 9 June 2009, at 3:36 a.m.

In Response To: HDR Primary and Secondary on different Versions (ANEES AHMAD)

Hi,

it is not said explicitly that HDR does not work at all
with different versions for IDS. And (obviously) the
non-functioning is not enforced by IDS.

But what is said explicitly is that different versions
of IDS are not supported for HDR. This means that if
sometime in the future you run into a problem with
your HDR configuration, then nobody will be able
to help you.

[ HDR is using the logical log records to implement
replication. Sometimes the internal format of
these logical log records changes between versions
and new logical log records get added over time to
support new functionality. Such new or changed
log records cannot be supported by an older version
of IDS. And since this is not supported, even the
behaviour when encountering such a log record is
in general unpredictable. It may "only" crash the
system (then at least you'd know something bad
happened). Worse, it may be interpreted wrongly and
thus corrupt your data logically, but go otherwise
unnoticed. In that case you'd have corrupted data
without knowing about it.

I would not trust even extensive testing, because
I would not know for sure, that all the constellations
of different log records have been covered enough
by any test scenario. Therefore it is (I think) practically
impossible to exclude the arrival of a "strange" log
record sometime in the future. And therefore I would
not run HDR with different versions of IDS - anyway
not over a longer period of time. Rolling upgrades
are in interesting topic, but not in the scope of this
e-mail ... :-)
]

Regards, Martin
--
Martin Fuerderer
IBM Informix Development Munich, Germany
Information Management

IBM Deutschland Research & Development GmbH
Chairman of the Supervisory Board: Martin Jetter
Board of Management: Erich Baier
Corporate Seat: Boeblingen, Germany
Reg.-Gericht: Amtsgericht Stuttgart, HRB 243294

ids-bounces@iiug.org wrote on 09.06.2009 08:16:36:

> Hello,
>
> I have created a scenario where my HDR primary server is on IDS11.
> 4FC3W1 where
> as HDR secondary server is on IDS11.5 FC4 and I am observing that
replication
> is working fine. I have also tested it in reverse order with HDR primary
is
> having 11.5FC4.
> It looks strange to me. As far as I know both versions should be same
while
> setting up replication, but here in my case both are different.
> Does anybody know, whether its functionality of bug?
>
> Regards,
> Anees Ahmad
>
>
>
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>

Messages In This Thread

• HDR Primary and Secondary on different Versions
  ANEES AHMAD -- Tuesday, 9 June 2009, at 2:16 a.m.
  • Re: HDR Primary and Secondary on different Version
    Martin Fuerderer -- Tuesday, 9 June 2009, at 3:36 a.m.
  • Re: HDR Primary and Secondary on different Version
    Madison Pruet -- Tuesday, 9 June 2009, at 9:07 a.m.

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