Two Questions on Restarting HDR (critical data undamaged)

Informix 10 Solaris 10 We have recently started using HDR, and are planning a test. The test will be to simulate a failure of the primary by doing an onmode -k. Our secondary has DRAUTO set to 0, so we will manually change the secondary to Standard. QUESTION #1: Can we do this by executing an onmode -d standard on the secondary? The documentation is not clear on this. In the Admin Guide section "Actions to Take If the Primary Database Server Fails", subsection "Manual Switchover", it contains the following two sentences about doing a manual switchover: "The secondary database server rolls back any open transactions and then comes into online mode as a standard database server, so that it can accept updates from client applications. For an explanation of how to perform the switchover, see Changing the Database Server Type." The referenced explanation ("Changing the Database Server Type") says to run the scripts "hdrmkpri.sh" on the secondary, and "hdrmksec.sh" on the primary. This would change the primary to a secondary, and the secondary to a primary, which is something we do NOT want to do. We just want to change to Standard, as mentioned int the "Manual Switchover" subsection. Hence the question above. Can we just use "onmode -d standard" to (temporarily) change the secondary to standard? If not, how does one effect the "Manual Switchover" to Standard? OK. Now, assuming we have successfully changged the secondary to standard, and accumulated some updates (by redirecting the clients), a

davidegrove@gmail.com wrote: > Informix 10 > Solaris 10 > > We have recently started using HDR, and are planning a test. The test > will be to simulate a failure of the primary by doing an onmode -k. > Our secondary has DRAUTO set to 0, so we will manually change the > secondary to Standard. > > QUESTION #1: > > Can we do this by executing an onmode -d standard on the secondary? It's better to switch the secondary to the primary. I'd suggest reserving onmode -d standard for the situations where you want to permanently split the two nodes into independent nodes. > > The documentation is not clear on this. In the Admin Guide section > "Actions to Take If the Primary Database Server Fails", subsection > "Manual Switchover", it contains the following two sentences about > doing a manual switchover: > > "The secondary database server rolls back any open transactions and > then comes into online mode as a standard database server, so that it > can accept updates from client applications. For an explanation of how > to perform the switchover, see Changing the Database Server Type." > > The referenced explanation ("Changing the Database Server Type") says > to run the scripts "hdrmkpri.sh" on the secondary, and "hdrmksec.sh" > on the primary. This would change the primary to a secondary, and the > secondary to a primary, which is something we do NOT want to do. > > We just want to change to Standard, as mentioned int the "Manual > Switchover" subsection. Hence the question above. Can we just use > "onmode -d standard" to (temporarily) change the secondary to > standard? If not, how does one effect the "Manual Switchover" to > Standard? > > OK. Now, assuming we have successfully changged the secondary to > standard, and accumulated some updates (by redirecting the clients), a I'm guessing that the rest of the message is missing...

"Madison Pruet" <mpruet1@verizon.net> wrote in message news:483E296E.8050000@verizon.net... > davidegrove@gmail.com wrote: >> Informix 10 >> Solaris 10 >> >> We have recently started using HDR, and are planning a test. The test >> will be to simulate a failure of the primary by doing an onmode -k. >> Our secondary has DRAUTO set to 0, so we will manually change the >> secondary to Standard. >> >> QUESTION #1: >> >> Can we do this by executing an onmode -d standard on the secondary? > > It's better to switch the secondary to the primary. I'd suggest reserving > onmode -d standard for the situations where you want to permanently split> the two nodes into independent nodes. > Thank you, Madison. Would you expand just a little? Are you suggesting that it would be better to switch the primary and secondary? I mean switching just the secondary would result in two primaries, which wouldn't be very nice, would it. The documentation does specifically refer to changing the secondary to standard and then returning to secondary, but, given that Madison Pruet is the absolute "go to guy" regarding replication, I will trust your advice over the documentation any day of the week. I just want to make sure I understand. My second question, which was truncated as you suspected, quoted from a later section of the Admin Guide where the procedure is described to revert the former-secondary-but-now-standard back to being a secondary, AND with full resyncing of the (new) updates on the secondary back to the primary (automatically and without re-initializing HDR). The procedure described in the documentation was quite simple: onmode -s on the former secondary (that would now be a standard), followed by onmode -d secondary <primary> (again on the former secondary), followed by oninit (on the primary). (Assuming logs haven't rolled over.) I think that procedure was described in Table 48 or 49. It sounded so perfectly desirable that I was licking my lips. So, the actual second question asked whether that section of the Admn Guide was something I could really count on. Or maybe I misunderstood. Or maybe the documentation wasn't really accurate. It sould seem to follow from your recomendation above (to change the secondary to primary [and, I am presuming, to also change the primary to secondary]) that the procedure in the Admin Guide to revert a standard back to secondary, with full resyncing from the secondary back to the primary (it did seem strange to me, but a plain text reading of the documentation seems to permit no other interpretation) is either not recommended, or just plain incorrect. Do I have it right, now? Then, following up... If I reverse the primary and secondary, can I then again do another reversal to achieve the original configuration, and with full sync that includes all updates made to the original secondary (which became a primary while the original primary was down), and without having to reinitialize HDR from scratch? Thank you for any further comments. Regards, David Grove

informix-list-bounces@iiug.org wrote on 05/29/2008 03:27:27 AM: > > "Madison Pruet" <mpruet1@verizon.net> wrote in message > news:483E296E.8050000@verizon.net... > > davidegrove@gmail.com wrote: > >> Informix 10 > >> Solaris 10 > >> > >> We have recently started using HDR, and are planning a test. The test > >> will be to simulate a failure of the primary by doing an onmode -k. > >> Our secondary has DRAUTO set to 0, so we will manually change the > >> secondary to Standard. > >> > >> QUESTION #1: > >> > >> Can we do this by executing an onmode -d standard on the secondary? > > > > It's better to switch the secondary to the primary. I'd suggest reserving > > onmode -d standard for the situations where you want to permanentlysplit > > the two nodes into independent nodes. > > > > Thank you, Madison. > > Would you expand just a little? Are you suggesting that it would be better > to switch the primary and secondary? I mean switching just the secondary > would result in two primaries, which wouldn't be very nice, would it. The > documentation does specifically refer to changing the secondary to standard > and then returning to secondary, but, given that Madison Pruet is the > absolute "go to guy" regarding replication, I will trust your advice over > the documentation any day of the week. I just want to make sure I > understand. > > My second question, which was truncated as you suspected, quoted from a > later section of the Admin Guide where the procedure is described to revert > the former-secondary-but-now-standard back to being a secondary, AND with > full resyncing of the (new) updates on the secondary back to the primary > (automatically and without re-initializing HDR). The procedure described in > the documentation was quite simple: onmode -s on the former secondary (that > would now be a standard), followed by onmode -d secondary <primary> (again > on the former secondary), followed by oninit (on the primary). (Assuming > logs haven't rolled over.) I think that procedure was described in Table 48 > or 49. > > It sounded so perfectly desirable that I was licking my lips. > > So, the actual second question asked whether that section of the Admn Guide > was something I could really count on. Or maybe I misunderstood. Or maybe > the documentation wasn't really accurate. Yes - you can count on that, primary will get in sync with secondary (new updates). > > It sould seem to follow from your recomendation above (to change the > secondary to primary [and, I am presuming, to also change the primary to > secondary]) that the procedure in the Admin Guide to revert a standard back > to secondary, with full resyncing from the secondary back to the primary (it > did seem strange to me, but a plain text reading of the documentation seems > to permit no other interpretation) is either not recommended, or just plain > incorrect. > > Do I have it right, now? > > Then, following up... If I reverse the primary and secondary, can I then > again do another reversal to achieve the original configuration, and with > full sync that includes all updates made to the original secondary (which > became a primary while the original primary was down), and without having to > reinitialize HDR from scratch? Yes - you can do another reversal, without having to reinitialize HDR from scratch. > > Thank you for any further comments. > > Regards, > > David Grove > > > _______________________________________________ > Informix-list mailing list > Informix-list@iiug.org > http://www.iiug.org/mailman/listinfo/informix-list