Category Archives: 19c

Exadata, REQUIRED_MIRROR_FREE_MB and GRID 19.19

I already wrote about the issue introduced with GI 19.16 in my previous post (click here to read) where (only at Exadata) more space was allocated/reserved by Oracle to guarantee mirror/rebalance. Fortunately, after some months of discussion, they rollbacked the change and released one patch that can be applied at GI 19.19.

The patch was released on 12 of June and it is the number 35285795 and can be only applied at GI 19.19. But to have your space back again there is one important rule: your mirroring needs to be HIGH. This is necessary because the “Smart Rebalance” that allows your disk to be dropped without losing the mirroring. I will write another post just to talk about it.

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Exadata version 23.1.0.0.0 – Part 02

On 08/March/2023 the Oracle Exadata team released version 23.1.0.0.0 and this include a significant change, OEL 8. I already explained that in my first post that you can read here. Here I will show how to patch to the 23.1.0.0 version for switch and storage cells.

Patching

As you know, I am working with Exadata since 2010 and have already posted about how to upgrade to the 19x version,  18.x version, version 12.x (Portuguese only), and many other details for Oracle Engineered Systems. Fortunately, I had the opportunity to apply the 23.1 version over one environment and will show the details.

Here, my environment is:

  • Exadata X6 for storage and dbnodes.
  • InfiniBand Switches.
  • Virtualized configuration (dom0 and domU).
  • dom0 running over version 22.1.0.9.
  • domU running over version 22.1.0.9.
  • Grid Infrastructure running version 19.17.

Since I am running with dom0/domU, my base machine (from where I will call most of the patches) is the dom0. There, I have ssh passwordless/keyless to all other cells, dbnodes, domU, and switches.

Before you start the patch please check the readme for the patch and identify if you have everything in compliance. Do not start any patch if you meet the requirements. Even from a simple database version, grid, and switch versions. And as well, do not start the patch if your machine has HW errors. So, please read the note Exadata System Software 23.1.0.0.0 Update (32829291) (Doc ID 2772585.1).

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Exadata version 23.1.0.0.0 – Part 01

On 08/March/2023 the Oracle Exadata team released version 23.1.0.0.0 and this include a significant change, OEL 8. But is not just that, other interesting requirements are there and I will discuss them below. I will show you how to patch to the 23.1 version and some other details as well. In this first part, I will just discuss one interesting point that you need to take care of before you start to patch. And probably is more important than you imagine.

Before you patch

The new version brings some requirements (over what you need to be running) to allow you to patch. For the Grid Infrastructure, you need to run 19.15 or a newer version. You can even run the 21c (21.6 or newer) version if you want. If you want to know how to do that, I already discussed how to upgrade both in previous posts (19c, and 21c).

For databases, the recommendation is the same, 19c or 21c. You can still run older versions (11,g, 12c, and 18) but they are already (or will be soon) under Market Driver Support. You can read the MOS note over that (here), but to be clear (now) only the 19c have premier support available.

And now things became quite interesting because the new 23.1 version is the first running with OEL 8. And if you check the supplemental README for the 23.1 version just the 19c support the database and GI are listed. So, be aware and check the compatibilities.

One important detail for this version is that you can only upgrade to 23.1 if your base Exadata running version is newer or equal to 21.2.10 (basically one year old only). If not, you need to upgrade to (at least) this version before you patch to 23.1. And this will be the same in the one-year future, it will be only possible to upgrade to 24.x if you will be running (at least) 23.1.

If you are running the old Exadata with InfiniBand, your dom0 will always be updated until Oracle Linux 7 with UEK5. For domU you can upgrade to the OEL 8. And you can upgrade in any order, first dom0 or domU. If you are running RoCE, your dom0 can run the latest OEL 8 UEK6. The blog post from Oracle made an excellent explanation about the upgrade paths and below you can see the images that are there (I used the image from their post).

So, as usual, the version includes everything, switches, storage, and database node. And while for switches and storages, the patches are quite normal, for virtualized environments the upgrades paths start to be a little more challenging to plan. I will explain, but (as hinted in the blog post) the upgrade of the Hosts and Guests independently and in any order. And is hard not because of the patch apply itself, but will be to create the plan. Remember the requirements for Oracle Database and GI? So, you can spend a lot of time patching others parts than the Exadata version.

But let’s put pieces together, the small lines written in several places. With this version 23.1, Oracle is telling you that you need to be running at least the Oracle Database 19c to be allowed to have a continuous upgrade for future releases (and possible usage) of Exadata. And whatever the machine version that you use, IB or RoCE network. You can’t anymore use GI older than 19.15, and the databases are enforced, as well, to be this version too. Imagine that you have some kind of incapability between 11g/12c and OEL 8, if you need to open one SR, you need to have/pay for that support, and will not be cheap.

And if you think the upcoming 23c (and that it will be the new LTS version) being in OEL 8 is a requirement. Imagine one year in the future, when the Exadata 24.x version will arrive, do you think that Oracle still supports 11g to the new OEL 9? I don’t think so.

And by the way, IMHO you should be running to 19c. 11G is from 2009, 12.1 from July 2013. So, they are old and out of support for good reasons. I understand the point that they are working on and the legacy applications that maybe you have. But the point is not just to support them, is the case to be possible to continue to upgrade/update your Exadata. Please do not postpone your database upgrades anymore, for the good sake of your Exadata. 

 

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Exadata, REQUIRED_MIRROR_FREE_MB and GRID 19.16

Starting with Grid Infrastructure/ASM 19.16 Oracle changed how the REQUIRED_MIRROR_FREE_MB is calculated and the impact is more than expected. Check below examples of the changes, and how this will impact you. This is valid for all GI/ASM starting with 19.16 and only for Exadata/ExaCC.

Please read my new post about this issue.

REQUIRED_MIRROR_FREE_MB

The REQUIRED_MIRROR_FREE_MB (according to 19c documentation) is:

amount of space that must be available in a disk group to restore full redundancy after the worst failure that can be tolerated by the disk group without adding additional storage. This requirement ensures that there are sufficient failure groups to restore redundancy”.

And (at Exadata environment until 19.16) is calculated based on the disk redundancy that you have. If you choose the HIGH, the raw size of two disks (the largest in your diskgroup) is reserved; at NORMAL, is the raw size of one disk. At Exadata, it differs from other environments because does not consider the whole failgroup failure and the way that extends are written/spread (more info below and in another post).

But for now, understand that the required size is what you need to reserve (as raw space) at your diskgroup to ensure protection in case of disk failure. And it is directly related to the USABLE_FILE_MB because the space that you can allocate at your diskgroup (USABLE_FILE_MB) comes from (FREE_MB- REQUIRED_MIRROR_FREE_MB)/redundancy factor (3 for HIGH, 2 for NORMAL). So, when you increase the REQUIRED_MIRROR_FREE_MB you reduce the USABLE_FILE_MB. I will explain more later.

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Duplicate PDB from active database, ASM, and OMF

Starting with 18c is possible to duplicate one PDB from an active database. This is a cool feature that helps a lot in daily activities. But recently I got one error when the destination is using ASM, and the files (of course) are managed using OMF. The solution is simple and is related to a bug that is affecting the 18c, 19c, and 21c versions.

Duplicating pluggable databases can be done for a long time and have some rules. But the duplicate PDB from an active database to a new CDB helps a lot because everything can be done online. We don’t need to create an intermediate CDB to export this PDB doing the unplug/plug, or cloning the source locally to read-only PDB and create a new one using dblink, or even using rman backups.

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21c Grid Infrastructure Upgrade

With the release of the 21c of Oracle Database is time to study new features. The 21c version of Grid Infrastructure (and ASM) was released and an upgrade from orders versions can be executed. It is not a complex task, but some details need to be verified. In this post, I will show the steps to upgrade the Grid Infrastructure to 21c. If you need to upgrade from 18c to 19c you can check my previous post.

Planning

The first step that you need to do is plan everything. You need to check the requirements, read the docs, download files, and plan the actions. While I am writing this post, there is no official MOS docs about how to upgrade the GI to 19c. The first place to the procedure is the official doc for GI Installation and Upgrade, mainly chapter 11. And another good example is 19c Grid Infrastructure and Database Upgrade steps for Exadata Database Machine running on Oracle Linux (Doc ID 2542082.1).

So, what you need to consider:

  • OS version: If it is compatible with 21c and if you are using asmlib or asm filter, check kernel modules and certification matrix.
  • Current GI: Maybe you need to apply some patches. The best practice recommends using the last version.
  • Used features (like AFD, HAIP, Resources): Check compatibilities of the old features with 21c. Maybe you need to remove HAIP or change your crs resources.
  • 21c requirements for GI: Check memory, space, and database versions.
  • Oracle Home patches (for databases running): Check if you need to apply some patches for your database to be compatible with GI 21c.
  • Backup of your Databases: Just in case you need to roll back something.

My environment

The environment that I am using for this example is:

  • Oracle Linux 8.4.
  • GI cluster with two nodes.
  • ASM Filter for disk access.
  • 19.11 for GI.
  • 19.12 for Oracle Home database.

I personally recommend upgrading your current GI to 19c before upgrade or apply one of the last PSU for your running version. This avoids a lot of errors since most of the know bugs will be patched. Check below my environment:

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ZDLRA + MAA, Protection for Gold Architecture

The Gold architecture for MAA is used to emphasis the application continuity. All the possible outages (planned or no) are protected by Oracle features. Here we are one step further and start to design using multi-site architecture. Data Guard, RAC, Oracle Clusterware, everything is there. But even with these, ZDLRA is still needed to allow complete protection.

The image above taken from https://www.oracle.com/a/tech/docs/maa-overview-onpremise-2019.pdf.

With the MAA references, we have the blueprints and highlights how to protect them since the standalone/single instance until the multiple site database. But for Gold we are beyond RPO and RTO, they are important but application continuity and data continuity join to complete the whole picture.

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Fast-Start Failover, Observe-Only Mode and Health Conditions

Oracle Data Guard Broker allows the database administrators to automate some tasks and an easy way to configure properly a lot of features and details for data guard environments. The Fast-Start FailOver (FSFO) allows the broker to automatically failover to standby database in case of failure of the primary. But until 19c the only option is always to trigger the failover. This changed at 19c with a nice new feature that allows us to put FSFO in Observe-Only Mode.

In this post, I will focus just on new features for FSFO like Observer-Only Mode and Health Conditions for it. Lag and other details will not be covered here.

Observe-Only Mode

The Observe-Only Mode is a simple change that allows putting the FSFO to just observing/monitoring the DG environment, but in case of failure, it does not change the roles between primary and standby. Simple like that. As the Broker documentation for Observe-Only Mode says:

The observe-only mode enables you to test the impact of using fast-start failover in your configuration, without making any actual changes to the configuration.

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ZDLRA, Patch the Recovery Appliance

The proceed to patch/upgrade ZDLRA is not complicated, but as usual, some details need to be checked before starting the procedure. Since it is one engineering system based at Exadata, the procedure has one part that (maybe) needs to upgrade this stack too. But, is possible to upgrade just the recovery appliance library.

Whatever if need or no to upgrade the Exadata stack, the upgrade for recovery appliance library is the same. The commands and checks are the same. The procedure described in this post cover the upgrade of the recovery appliance library. For Exadata stack, it is in another post.

Where we are

Before even start the patch/upgrade it is important to know exactly which version you are running. To do this execute the command racli version at you database node:

[root@zeroinsg01 ~]# racli version
Recovery Appliance Version:
        exadata image: 19.2.3.0.0.190621
        rarpm version: ra_automation-12.2.1.1.2.201907-30111072.x86_64
        rdbms version: RDBMS_12.2.0.1.0_LINUX.X64_RELEASE
        transaction  : kadjei_julpsu_ip2
        zdlra version: ZDLRA_12.2.1.1.2.201907_LINUX.X64_RELEASE
[root@zeroinsg01 ~]#

With this, we can discover the ZDLRA version running (12.2.1.1.2.201907 in this case), and the Exadata image version (19.2.3.0.0.190621).

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19c Grid Infrastructure Upgrade

Upgrade GRID infrastructure is one activity that usually is postponed because it involves a sensible area that, when not works, causes big downtime until be fixed. But, in the last versions, it is not a complicated task and if you follow the basic rules, it works without problems.

Here I will show a little example of how to upgrade the GI from 18.6.0 to 19.5. The steps below were executed at Exadata running version 19.2.7.0.0.191012 and GI 18.6.0.0, but can be done in every environment that supports Oracle GI.

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