Author Archives: Ludovico

About Ludovico

Ludovico is a member of the Oracle Database High Availability (HA), Scalability & Maximum Availability Architecture (MAA) Product Management team in Oracle. He focuses on Oracle Data Guard, Flashback technologies, and Cloud MAA.

When it comes to using Oracle, trust Oracle…

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A month ago, I saw this article published on the AWS architecture blog:

Disaster Recovery for Oracle Database on Amazon EC2 with Fast-Start Failover

I love seeing people suggesting Oracle Data Guard Fast-Start Failover for high availability. Nevertheless, there are a few problems with the architecture and steps proposed in the article.

I sent my comments via Disqus on the AWS blogging platform, but after a month, my comment was rejected, and the blog content hasn’t changed.

For this reason, I don’t have other places to post my comment but here…

  1. The link to the setup procedure is from 2009.
    We have official documentation that we keep up to date. The Fast-Start Failover part:
    https://docs.oracle.com/en/database/oracle/oracle-database/19/dgbkr/using-data-guard-broker-to-manage-switchovers-failovers.html#GUID-D26D79F2-0093-4C0E-98CD-224A5C8CBFA4
    and the Best Practices guide:
    https://docs.oracle.com/en/database/oracle/oracle-database/19/haovw/oracle-data-guard-best-practices.html#GUID-C3A78B07-6584-4380-8D53-E5B831A5894C
  2. The part about cascading standbys references a step-by-step guide from an external blog written many years ago for 11gR2.
  3. The DBMS_SERVICE doc is from 12cR1, while other links are from 21c doc or 19c doc. As of today, most implement 19c. That’s probably the version to use.
    https://docs.oracle.com/en/database/oracle/oracle-database/19/arpls/DBMS_SERVICE.html#GUID-C11449DC-EEDE-4BB8-9D2C-0A45198C1928
  4. The steps used to create the database service do not include any HA property, which will make most efforts useless. (see Table 153-6 in the link above).
  5. The article talks about TAF, but no steps exist to configure it. We don’t recommend TAF since 12c anyway. Today (19c), the recommendation is TAC (Transparent Application Continuity).
    https://www.oracle.com/docs/tech/application-checklist-for-continuous-availability-for-maa.pdf
  6. But, most important, TAF (or Oracle connectivity in general) does NOT require a host IP change! There is no need to change the DNS when using the recommended connection string with multiple address_lists.
  7. Some RedoRoutes examples are not correct. In this video I explain how they work and how to set them up:
    https://www.youtube.com/watch?v=huG8JPu_s4Q
  8. The diagram shows the master observer together with the standby database, which is a bad practice. I explain why and how here:
    https://www.youtube.com/watch?v=e81UPLfnLi0

The central message is:

If you need to implement a complex architecture using a software solution, pay attention that the practices suggested by the partner/integrator/3rd party match the ones from the software vendor. In the case of Oracle Data Guard, Oracle knows better 😉

Cheers

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Ludovico

 

Video: Where should I put the Observer in a Fast-Start Failover configuration?

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The video explains best practices and different failure scenarios for different observer placements. It also shows how to configure high availability for the observer.

Here’s the summary:

  • Always try to put the observer(s) on an external site.
  • If you don’t have any, put it where the primary database is, and have one ready on the secondary site after the role transition.
  • Don’t put the observer together with the standby database!
  • Configure multiple observers for high availability, and use the PreferredObserverHosts Data Guard member property to ensure you never run the observer where the standby database is.

 

Find Ludovico at Oracle Cloud World 2022!

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Are you attending OCW, and do you want to find me and know more about how to avoid downtime and data loss? Or how to optimize your application configuration to make the most out of MAA technologies? Or any database, or technology-related topic?

Maybe you prefer just a chat and discussing life? Over a coffee, or tea? (or maybe beer?)

👇This is where you can find me during OCW.👇

Monday, October 17, 2022

6:30 PM – 10:00 PM – Customer Appreciation Event

Where: Mandalay Bay Shark Reef

This is an invitation-only event. If you are one of the lucky customers that possess an invitation, let’s meet there! It will be fun to discuss technology, business, and life while watching sharks and enjoying a drink together.

Tuesday, October 18, 2022

2:00 PM – 4:30 PM – Oracle Maximum Availability Architecture with Oracle RAC and Active Data Guard

Where: CloudWorld Hub, Database booth DB-01

Come together and ask anything Data Guard, Active Data Guard, RAC, FPP, or High Availability! See some products in action, and get some insights from my colleagues and me. The booth will be open during the whole exhibition time, but I will be certainly there on Tuesday for these two hours.

4:00 PM – 5:30 PM – Protect Your Business Using Oracle Full Stack Disaster Recovery Service –  Interactive Hands-On-Lab [HOL4089]

Where: Bellini 2003, The Venetian, Level 2

I will help my colleague Suraj Ramesh run the hands-on lab of this brand-new (actually, still to be released!) service for general-purpose Disaster Recovery in the cloud.

After HOL4089 until – 7:00 pm – Welcome Reception

Where: CloudWorld Hub, Database booth DB-01

I will probably join to say hello during the Welcome Reception. Maybe you can spot me there 🙂

Wednesday, October 19, 2022

10:00 AM – 12:00 PM – Oracle Maximum Availability Architecture with Oracle RAC and Active Data Guard

Where: CloudWorld Hub, Database booth DB-01

I will be there once again to answer all your questions and show some fancy stuff 🙂

1:15 PM – 2:00 PM – Oracle Data Guard—Active, Autonomous, and Always Protective [LRN3528]

Where: San Polo 3403, The Venetian, Level 3

I will talk about Data Guard, Active Data Guard, and what I consider the most important features today. Come to the session to know more!

3:00 PM – 4:30 PM – Protect Your Data with Oracle Active Data Guard – Interactive Hands-On-Lab [HOL4054]

Where: Bellini 2003, The Venetian, Level 2

I will run this hands-on lab. You will have an Active Data Guard 19c configuration in the cloud at your fingertips and you will play with role changes, corruption detection and reparation, and other features. I will be there to explain insights, hints, and recommendations on how to implement it in your work environment.

Thursday, October 20, 2022

11:40 AM – 12:00 PM – The Least-Known Facts About Oracle Data Guard and Oracle Active Data Guard [LIT4029]

Where: Ascend Lounge, CloudWorld Hub, The Venetian

This will be great! I bet you will discover MANY things that you did not know about Data Guard and Active Data Guard. Come to know more!

 

See you there!

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Ludovico

Check, check… Does the mic still work? #JoelKallmanday

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Update PHP: ✔
Update WordPress: ✔
New content: ⌛

It’s almost six months without blogging from my side. What a bad score!
It’s not a coincidence that I’m blogging today during #JoelKallmanDay.
A day that reminds the community how important it is to share. Knowledge, mostly. But also good and bad experiences, emotions…

A bittersweet day, at least for me.
On the bitter side: it reminds me of Joel, Pieter, and other friends that are not there anymore. That as a Product Manager, I have to wear big shoes, and it does not matter how good I try to do; I will always feel that it’s not good enough for the high expectations that I set for myself. Guess what! Being PM is way more complicated than I expected when I applied for the position two years ago. So many things to do or learn, so many requests, and so many customers! And being PM at Oracle is probably twice as complicated because it does not matter how good I (or we as a team) try to do; there will always be a portion of the community that picks on the Oracle technology for one reason or another.

On the bright side: it reminds me that I am incredibly privileged to have this role, working in a great team and helping the most demanding customers to get the most out of incredible technology. I love sharing, teaching, giving constructive feedback, producing quality content, and improving the customer experience. This is the sweet part of the job, where I am still taking baby steps when comparing myself to the PM legends we have in our organization. They are always glad to explain our products to the community, the customers, and colleagues! And they are all excellent mentors, each with a different style, background, and personal life.

And knowing people personally is, at least for me, the best thing about being part of a community (outside Oracle) and team (inside Oracle). We all strive for the best technical solutions, performance, developer experience, or uptime for the business. But we are human first of all. And this is what #JoelKallmanDay stands for me—trying to be a better human as a goal so that everything else comes naturally, including being a great colleague, community servant, or friend. ♥

Far Sync and Fast-Start Failover Protection modes

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Oracle advertises Far Sync as a solution for “Zero Data Loss at any distance”. This is because the primary sends its redo stream synchronously to the Far Sync, which relays it to the remote physical standby.

There are many reasons why Far Sync is an optimal solution for this use case, but that’s not the topic of this post 🙂

Some customers ask: Can I configure Far Sync to receive the redo stream asynchronously?

Although a direct standby receiving asynchronously would be a better idea, Far Sync can receive asynchronously as well.

And one reason might be to send asynchronously to one Far Sync member that redistributes locally to many standbys.

It is very simple to achieve: just changing the RedoRoutes property on the primary.

This will work seamlessly. The v$dataguard_process will show the async transport process:

 

What about Fast-Start Failover?

Up to and including 19c, ASYNC transport to Far Sync will not work with Fast-Start Failover (FSFO).

ASYNC redo transport mandates Maximum Performance protection mode, and FSFO supports that in conjunction with Far Sync only starting with 21c.

Before 21c, trying to enable FSFO with a Far Sync will fail with:

So if you want FSFO with Far Sync in 19c, it has to be MaxAvailability (and SYNC redo transport to the FarSync).


If you don’t need FSFO, as we have seen, there is no problem. The only protection mode that will not work with Far Sync is Maximum Protection:

If FSFO is required, and you want Maximum Performance before 21c, or Maximum Protection, you have to remove Far Sync from the redo route.

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Ludovico

Can a physical standby database receive the redo SYNC if the Far Sync instance fails?

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The answer is YES.

In the following configuration, cdgsima_lhr1pq (primary) sends synchronously to cdgsima_farsync1 (far sync), which forwards the redo stream asynchronously to cdgsima_lhr1bm (physical standby):

But if cdgsima_farsync1 is not available, I want the primary to send synchronously to the physical standby database. I accept a performance penalty, but I do not want to compromise my data protection.

I just need to set up the Redoroutes as follows:

This is defined the second part of the RedoRoutes rules:

Let’s test. If I shutdown abort the farsync instance:

I can see the new SYNC destination being open almost instantaneously (because the old destination fails immediately with ORA-03113):

Indeed, I can see the new NSS process (synchronous redo transport) spawn at that time:

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Ludo

Can I rename a PDB in a Data Guard configuration?

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Someone asked me this question recently.

The answer is: yes!

Let’s see it in action.

On the primary I have:

And of course the same PDBs on the standby:

Let’s change the PDB RED name to TOBY: The PDB rename operation is straightforward (but it requires a brief downtime). To be done on the primary:

On the standby, I can see that the PDB changed its name:

The PDB name change is propagated transparently with the redo apply.

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Ludo

rhpctl addnode gihome: specify HUB or LEAF when adding new nodes to a Flex Cluster

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I have a customer trying to add a new node to a cluster using Fleet Patching and Provisioning.

The error in the command output is not very friendly:

The “RHPHELP_preNodeAddVal” might already give an idea of the cause: something related to the “cluvfy stage -pre nodeadd” evaluation that we normally do when adding a node by hand. FPP does not really run cluvfy, but it calls the same primitives cluvfy is based on.

In FPP, when the error does not give any useful information, this is the flow to follow:

  • use “rhpctl query audit” to get the date and time of the failing operation
  • open the “rhpserver.log.0” and look for the operation log in that time frame
  • get the UID of the operation e.g., in the following line it is “1556344143”:

  • Isolate the log for the operation: grep $UID rhpserver.log.0 > $UID.log
  • Locate the trace file of the rhphelper remote execution:

  • Find the root cause in the rhphelper trace:

In this case, the target cluster is a Flex Cluster, so the command must be run specifying the node_role.

The documentation is not clear (we will fix it soon):

node_role must be specified for Flex Clusters, and it must be either HUB or LEAF.

After using the correct command line, the command succeeded.

HTH

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Ludovico

Changing FPP temporary directory (/tmp in noexec and other issues)

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When using FPP, you might experience the following error (PRVF-7546):

This is often related to the filesystem /tmp that has the “noexec” option:

Although it is tempting to just remount the filesystem with “exec”, you might be in this situation because your systems are configured to adhere to the STIG recommendations:

The noexec option must be added to the /tmp partition (https://www.stigviewer.com/stig/red_hat_enterprise_linux_6/2016-12-16/finding/V-57569)

FPP 19.9 contains fix 30885598 that allows specifying the temporary location for FPP operations:

After that, the operation should run smoothly:

HTH

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Ludo