When a disk fails in an Exadata compute node, it should be replaced as soon as possible. Compute node disks are typically configured with RAID-5, which can tolerate only one disk failure. ⚠️ Important: RAID-5 does not create two copies of your data. It stores only one copy, with parity distributed across the other disksContinue reading “Understanding Disk Rebuilds After Replacement in Exadata Compute Nodes”
Category Archives: Non classé
When the Clustering Factor Strikes: How a “Perfect” Plan Turned into a 9-Second I/O Nightmare
This wasn’t a theoretical exercise—it was a real-world performance issue that left the database paralyzed.Let’s start with the global stats: The database wasn’t working—it was waiting.Over 90% of the query’s elapsed time was spent on I/O waits, meaning the database was stuck reading data from disk. Step 1: The Execution Plan At first view, theContinue reading “When the Clustering Factor Strikes: How a “Perfect” Plan Turned into a 9-Second I/O Nightmare”
Streamlit : Making Your Enterprise Knowledge Assistant AI Accessible
Last time, I built a working enterprise knowledge assistant in Python using RAG + OpenAI + Chroma. It could read documents, answer questions, and even remember chat history. Today, I’m taking it a step further: giving it a friendly web interface. Instead of typing commands in a terminal, employees can now interact with the assistantContinue reading “Streamlit : Making Your Enterprise Knowledge Assistant AI Accessible”
Building an Enterprise Knowledge Assistant with RAG, OpenAI, and a Vector Database
Many companies have a lot of documents — policies, procedures, meeting notes, and training materials.The problem: this knowledge is often hard to find. In this post, I’ll show how to build a simple Enterprise Knowledge Assistant using LangChain, OpenAI, and a vector database (Chroma).This AI assistant can read your internal files and answer employee questionsContinue reading “Building an Enterprise Knowledge Assistant with RAG, OpenAI, and a Vector Database”
Building a Simple RAG Q&A Assistant with LangChain and OpenAI
I recently explored how to combine LangChain and OpenAI’s GPT models to create an intelligent Retrieval-Augmented Generation (RAG) assistant. This project can read your local documents, store them in a searchable vector database, and answer questions based on your own text . What is RAG? RAG (Retrieval-Augmented Generation) is a powerful technique that combines informationContinue reading “Building a Simple RAG Q&A Assistant with LangChain and OpenAI”
Resizing an ASM Diskgroup on Exadata When OCR/Voting Files Are on It
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”
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!”
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”
Oracle DBA Insights 