Blog3s

To put it in bit of an Indian context, database is not your daughter-in-law that you can blame it for every performance issue that occurs in the environment. But it does happen. Most of the time it is the database that is blamed for all such issues. Many times, the issues are in some other layer like OS, network or storage. Faced this issue recently at one of the customer sites where performance in one of the databases went down suddenly. It was a 2 node RAC on 12.1.0.2 running on Linux 7 using some kind of Hitachi SSD storage array. There were no changes as per DBA, application, OS and storage teams. But something must have changed somewhere. Otherwise why would performance degrade just like that. I & my colleague checked some details and found that something happened in the morning a day before. Starting from that point in time, the execution time for all the commonly run queries shot up. Generally speaking, when all the queries are doing bad and you are sure that nothing has been changed on the database side, the reasons could be outside the database. But being a DBA, it is not easy to prove that. We took AWRs from good and bad times and the wait events section looked like this: ...

To put it in bit of an Indian context, database is not your daughter-in-law that you can blame it for every performance issue that occurs in the environment. But it does happen. Most of the time it is the database that is blamed for all such issues. Many times, the issues are in some other layer like OS, network or storage. Faced this issue recently at one of the customer sites where performance in one of the databases went down suddenly. It was a 2 node RAC on 12.1.0.2 running on Linux 7 using some kind of Hitachi SSD storage array. There were no changes as per DBA, application, OS and storage teams. But something must have changed somewhere. Otherwise why would performance degrade just like that. I & my colleague checked some details and found that something happened in the morning a day before. Starting from that point in time, the execution time for all the commonly run queries shot up. Generally speaking, when all the queries are doing bad and you are sure that nothing has been changed on the database side, the reasons could be outside the database. But being a DBA, it is not easy to prove that. We took AWRs from good and bad times and the wait events section looked like this: ...

To put it in bit of an Indian context, database is not your daughter-in-law that you can blame it for every performance issue that occurs in the environment. But it does happen. Most of the time it is the database that is blamed for all such issues. Many times, the issues are in some other layer like OS, network or storage. Faced this issue recently at one of the customer sites where performance in one of the databases went down suddenly. It was a 2 node RAC on 12.1.0.2 running on Linux 7 using some kind of Hitachi SSD storage array. There were no changes as per DBA, application, OS and storage teams. But something must have changed somewhere. Otherwise why would performance degrade just like that. I & my colleague checked some details and found that something happened in the morning a day before. Starting from that point in time, the execution time for all the commonly run queries shot up. Generally speaking, when all the queries are doing bad and you are sure that nothing has been changed on the database side, the reasons could be outside the database. But being a DBA, it is not easy to prove that. We took AWRs from good and bad times and the wait events section looked like this: ...

To be honest, Fernando Simon has already documented all the steps needed in ZDLRA patching . So this post is more like a reference post for me and it points to the links on his blog. One thing he could change though are the post titles. He also agrees ;) https://twitter.com/amardeep_sidhu/status/1370304085245661192 ZDLRA patching is broadly divided into two parts. First part is where you patch the RA library and Grid & DB homes. Second part includes compute node & storage cell image patch and patches for IB/RoCE switches. Second part is exactly similar to Exadata except that it is bit restricted in terms of image versions that you can use. Only the versions that are certified for ZDLRA can be used. Also the RA library version and the Exadata image version should be compatible with each other. So if you are planning to patch only one part; RA library or the image, make sure that both the components stay compatible. The MOS note that has all these details is 1927416.1. This note should be the first place to go when you are planning to patch a ZDLRA. The steps for upgrade/patch, image patching are given in MOS note 2028931.1. There is another note 2639262.1 that discusses some of the known issues that you may face while doing the patching. It is important to review all three notes before you plan to patch. ...

To be honest, Fernando Simon has already documented all the steps needed in ZDLRA patching . So this post is more like a reference post for me and it points to the links on his blog. One thing he could change though are the post titles. He also agrees 😉 The RA library patching part can be considered of two different types. This is an important difference. Make sure that you follow the right set of commands. When you are jumping between major versions say going from 12.x to 19.x, it is called an upgrade and the commands are like racli upgrade appliance –step=1. Fernando talks about this in detail in this post. ...