When you try to shrink an ASM diskgroup that holds Oracle Clusterware files (OCR and voting disks), you may hit errors like: Why it happens Even though Oracle bugs 24568147 and 37688474 mention fixes in newer releases (19.27 RU+), this issue still reproduces in 19.28 and 23.8. The voting files are persisted in the ASMContinue reading “Resizing an ASM Diskgroup on Exadata When OCR/Voting Files Are on It”
Author Archives: dbaliw
Be Careful: EX80 Issue Can Wipe Out Your Exadata/ZDLRA X8/X9 Data!
Recently, our ZDLRA X8-2 was impacted by the EX80 issue, resulting in the loss of three disks within a very short time. Two of these disks were partner disks, causing the DELTA disk group to unmount and all customer data to be lost. Oracle Support confirmed that recreating the DELTA disk group was not anContinue reading “Be Careful: EX80 Issue Can Wipe Out Your Exadata/ZDLRA X8/X9 Data!”
What Is a Bloom Filter in Oracle Database?
When working with big databases, speed matters. Oracle uses many smart tricks to make things faster. One of these tricks is called the Bloom filter. In this post, I’ll explain what it is and how it helps Oracle database run queries faster — in simple terms! The Problem: Big Tables and Slow Joins Let’s sayContinue reading “What Is a Bloom Filter in Oracle Database?”
Why Bitmap Indexes Can Wreck OLTP Systems
Bitmap indexes might seem like a great idea—they save space and are fast for certain types of queries. But in high-traffic OLTP systems, they can be a nightmare. Why? Because they don’t play well with frequent updates and lots of users at the same time. In fact, they can cause serious blocking and performance problems.Continue reading “Why Bitmap Indexes Can Wreck OLTP Systems”
AI for DBAs: Understanding AI Vectors
Imagine you’re building a robot librarian. Instead of organizing books by titles or authors, it groups them by meaning—romance novels near poetry, tech manuals near science fiction. This is exactly what AI vector databases do: they turn messy data (words, images, sounds) into meaningful numbers that machines can understand. Let’s break it down. 1. AI Vectors: Turning Chaos IntoContinue reading “AI for DBAs: Understanding AI Vectors”
How to fix “DROPPED” griddisk in Cell
You may encounter a situation where a grid disk is in a dropped status in oracle exadata cell storage. This issue can be identified using the following command: Additionally, the ASM alert log may show errors like: This error indicates that the grid disks do not have the same size, which is causing issues inContinue reading “How to fix “DROPPED” griddisk in Cell”
Unlocking Performance with Oracle 23AI’s True Cache
Oracle 23AI introduces a groundbreaking feature called True Cache, which provides an in-memory caching layer for frequently accessed data. This significantly improves read performance, especially in environments where quick access to repetitive data queries is critical. However, don’t confuse it with the “In-Memory” feature, as both serve very different use cases. Let’s explore the details.Continue reading “Unlocking Performance with Oracle 23AI’s True Cache”
Benefits of Zstandard Compression in Oracle 23ai HCC
In Oracle Database 23ai, significant improvements have been made to Hybrid Columnar Compression (HCC), with the default compression method now utilizing Zstandard (Zstd) instead of the previous algorithms, zlib and bzip2. But what exactly is Zstandard, and how does it differ from zlib and bzip2? Zstandard is a lossless data compression algorithm developed by YannContinue reading “Benefits of Zstandard Compression in Oracle 23ai HCC”
How to patch Exadata PDU
Recently, I collaborated with a colleague to promote our Exadata system to a new Oracle Enterprise Manager (OEM) server. However, we encountered issues when attempting to promote the Power Distribution Unit (PDU). After consulting My Oracle Support (MOS), we decided to address potential bugs by applying the latest PDU patch before proceeding with the promotionContinue reading “How to patch Exadata PDU”
What should we do if the Flash Cache is degraded in an Exadata cell
Flash cache plays a critical role in Exadata performance. When issues arise, it’s crucial to understand the symptoms and resolution steps. Typically, each flash cache comprises four flash disks. If one flash disk fails, the cell service automatically removes it while continuing to operate with the remaining three disks. In most cases, immediate intervention isContinue reading “What should we do if the Flash Cache is degraded in an Exadata cell”
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