Grid Infrastructure 12c: Recovering the GRID Disk Group and recreating the GIMR

Losing the Disk Group that contains OCR and voting files has always been a challenge. It requires you to take regular backups of OCR, spfile and diskgroup metadata.

Since Oracle 12cR1, there are a few additional components you must take care of:

– The ASM password file (if you have Flex ASM it can be quite critical)

– The Grid Infrastructure Management Repository

Why ASM password file is important? Well, you can read this good blog post form my colleague Robert Bialek: http://blog.trivadis.com/b/robertbialek/archive/2014/10/26/are-you-using-oracle-12c-flex-asm-if-yes-do-you-have-asm-password-file-backup.aspx

So the problem here, is not whether you should back them up or not, but how you can restore them quickly.

Assumptions: you back up regularly:

ASM parameter  file:

Oracle Cluster Registry:

ASM Diskgroup Metadata:

ASM password file:

What about the GIMR?

According to the MOS Note: FAQ: 12c Grid Infrastructure Management Repository (GIMR) (Doc ID 1568402.1), there is no such need for the moment.

Weird, huh? The -MGMTDB itself contains for the moment just the Cluster Health Monitor repository, but expect to see its important increasing with the next versions of Oracle Grid Infrastructure.

If you REALLY want to back it up (even if not fundamental, it is not a bad idea, after all), you can do it.

The -MGMTDB is in noarchivelog by default. You need to either put it in archivelog mode (and set a recovery area, etc etc) or back it up while it is mounted.

Because the Cluster Health Monitor (ora.crf)  depends on it, you have to stop it beforehand:

Then you can operate with -MGMTDB:

Now, imagine that you loose the GRID diskgroup (nowadays, with the ASM Filter Driver, it’s more complex to corrupt a device by mistake, but let’s assume that you do it):

The cluster will not start anymore, you need to disable the crs, reboot and start it in exclusive mode:

 

Then you can recreate the GRID disk group and restore everything inside it:

Finally, the last missing component: the GIMR.

You can recreate it or restore it (if you backed it up at some point in time).

Let’s see how to recreate it:

Conclusion

Recovering from a lost Disk Group / Cluster is not rocket science. Just practice it every now and then. If you do not have a test RAC, you can build your lab on your laptop using the RAC Attack instructions. If you want to test all the scenarios, the RAC SIG webcast: Oracle 11g Clusterware failure scenarios with practical demonstrations by Kamran Agayev is the best starting point, IMHO. Just keep in mind that Flex ASM and the GIMR add more complexity.

HTH

Ludovico

Another successful RAC Attack in Geneva!

ninja-suisseLast week I have hosted the second Swiss RAC Attack workshop at Trivadis offices in Geneva. It has been a great success, with 21 total participants: 5 Ninjas, 4 alumni and 14 people actively installing or playing with RAC 12c on their laptops.

Last year I was suprised by a participant coming fron Nanterre. This year two people came directly from Moscow, just for the workshop!

We’ve got good pizza and special beer: Chimay , Vedett, Duvel, Andechs…

Last but not least, our friend Marc Fielding was visiting Switzerland last week, so he took the opportunity to join us and make the workshop even more interesting! 😀
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Looking forward to organize it again in one year! Thank you guys 🙂

Ludovico

The Great Guys of Paris

When I started my contribution to the Oracle community, I was doing it for two reasons. The noble: Give back to the community what I have learnt from it. The narcissist: Try to be as good as my favourite bloggers and get fame and prestige.

What I was not expecting, is that now I am getting more from the community than what I was getting before starting my contribution. Not only at a technical level, but also in terms of friends, travels, network.

Earlier this summer, I have been invited, along with Franck Pachot, to present at the Paris Oracle Meetup. We have been there last Friday (4 Sept 2015), and it has been mind blowing.

Une après-midi avec Franck Pachot et Ludovico Caldara

Friday, Sep 4, 2015, 2:00 PM

Avnet Technology Solutions
29 rue des 3 fontanot Nanterre 7 ème étage nanterre, FR

47 Oracle Professionals Went

Les vacances ne sont pas finis, mais un nouveau meetup est déjà prévu pour cette rentrée.Nous aurons le plaisir d’accueillir une délégation suisse:) Franck Pachot (Oracle ACE et certifié OCM 11g, OCP 12c, Performance Tuning Expert, Exadata Implementation)  de la société dbi-services blog de Franckansi que Ludovico Caldara (Oracle ACE,member of th…

Check out this Meetup →

I’m excited about it because this meetup started only a couple of years ago, and it has already had speakers like Jonathan Lewis and Tom Kyte. But what surprises more, is the meetup has a near-zero budget.

The legend says that Gregory Gouillou and other french guys met Christian Antognini at the Open World (or was it UKOUG Tech?), discussed about the lack of active OUGs in France and then Chris said: “If you want it, make it happen”.

The Paris Oracle Meetup now is a reality, and I am proud of having been part of it.

Thank you @RBELHADJ, @Ycolin, @GregoryGuillou, @ParisOracle ! 🙂