High I/O (Input/Output) activity in an Oracle Database can indicate that the system is under heavy load and this may lead to performance issues. High CPU or High I/O are two key events that database admins monitor. High I/O can also cause disk bottlenecks, which can slow down the entire system.
Some steps as a DBA that you can take to address high I/O activity in an Oracle Database are as below:
- Monitor I/O activity: The first step in addressing high I/O activity is to monitor it. Oracle provides several performance views, such as V$FILESTAT and V$SYSSTAT, that can be used to monitor I/O activity. These views provide information on I/O activity, such as the number of physical reads, physical writes, and I/O wait time. By monitoring I/O activity, you can determine which files or tablespaces are causing the high I/O. You can use OEM if your projects use OEM as OEM shows it graphically in a nice way.
- Tune SQL statements: High I/O activity can often be caused by poorly tuned SQL statements. By analyzing the SQL statements that are causing the high I/O, you can determine if they can be optimized. For example, you can check if the SQL statements are using appropriate indexes, if the table statistics are up-to-date, or if the SQL statements can be rewritten to reduce the number of I/O operations. Here also OEM can help in locating the top SQLs.
- Check for disk bottlenecks: High I/O activity can also be caused by disk bottlenecks. To check for disk bottlenecks, you can use the operating system’s performance monitoring tools, such as iostat, to check the disk I/O rate, disk utilization, and disk queue length. If you find that disk bottlenecks are causing the high I/O, you may need to add more disk storage or consider using faster disk drives.
- Use storage tiering: Storage tiering is a technique that involves moving data between different types of storage based on the data’s access patterns. For example, you can use storage tiering to move frequently accessed data to solid-state drives (SSD) and infrequently accessed data to slower and cheaper hard disk drives (HDD). This can help reduce I/O activity on the faster and more expensive SSDs, and improve overall performance.
- Check for hardware failure: High I/O activity can also be caused by hardware failure. If you suspect that hardware failure is causing the high I/O, you should check the system logs and hardware status to see if any hardware components have failed. If hardware failure is found, you should replace the failed component.
High I/O activity in an Oracle Database can indicate that the system is under heavy load and this may lead to performance issues. By monitoring some of the above things you can locate causes of high I/O and fix the issues.
I’m an experienced Cloud/Oracle Applications/DBA Architect with more than 15 years of full-time DBA/Architect experience. I have gained wide knowledge on Oracle and Non-Oracle software stack running on-prem and on Cloud and have worked on several big projects for multi-national companies. I enjoy working with leading-edge technology and have a passion for Cloud architecture, automation, database performance, and stability. Thankfully my work allows me time for researching new technologies (and to write about them).
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