Measure the test taker's knowledge about the Oracle file system mechanism.

Oracle file system is a strange concept for many new users who are new to Oracle databases. The following describes in detail the Oracle file system mechanism, hoping to help you learn about Oracle.

In Oracle, you can use four Oracle file system mechanisms to store your data. Here we emphasize that "your data" refers to your data dictionary, redo records, undo records, tables, indexes, and LOB, that is, the data you care about every day. To put it simply, this includes:

"Cooked" operating system OS) File System

These files are stored in the file system like word processing documents. You can see these files in Windows resource manager, and on UNIX, you can see these files through the ls command. You can use a simple OS tool such as xcopy on Windows or cp on UNIX to move files. Historically, Cooked OS files have been the "most popular" Method for storing data in Oracle, but I personally think that with the introduction of ASM, I will explain it in detail later, this situation will change. Cooked file systems "process" file systems or "Cooked" file systems) are usually cached, which means that when you read or write a disk, the OS caches information for you.
Raw partition, also called raw partition)

This is not a file, but an original disk. You cannot use ls to view the content. You cannot view the content in Windows Resource Manager. These are some of the large sectors on the disk, without any file systems. For Oracle, the entire original partition is a large file. Unlike the cooked file system, the cooked file system may have dozens or even hundreds of database data files. Currently, only a few Oracle installations use the original partition, because the management overhead of the original partition is large. The original partition is not a buffer device, and all I/O operations are directly I/O, which does not buffer any OS data. This is usually an advantage for databases ).

Automatic Storage Management (ASM)

This is a new feature of Oracle 10 gRelease 1. Both the Standard Edition and Enterprise Edition provide this feature ). ASM is a file system specially designed for databases. You can simply regard it as a database file system. In this file system, the shopping list is not stored in a text file; here, the information related to the database can only be stored: your tables, indexes, backups, control files, parameter files, redo logs, and archive files. However, even ASM has corresponding data files. In terms of concept, the database is still stored in files, but the current file system is ASM. ASM is designed to work in a standalone or cluster environment.
Cluster File System

This file system is dedicated to the RAC cluster) Environment and looks like a cooked file system shared by multiple node computers in the cluster environment. The traditional cooked file system can only be used by one computer in the cluster environment. Therefore, although NFS loading can be used between multiple nodes in the cluster or Samba shares a cooked file system, Samba is similar to NFS, and disks can be shared between Windows and UNIX environments ), however, this will cause a loss. If a file system fails to be installed and shared nodes are provided, the file system is unavailable. Oracle Cluster File System (OCFS) is a new File System launched by Oracle in this field. It can only be used on Windows and Linux. Other third-party developers also provide some certified cluster file systems, which can also be used in Oracle. The cluster file system extends the advantages of the cooked File System to the cluster environment.

The database may contain files from all the above file systems. You do not have to select only one of them. In your database, some data may be stored in a traditional cooked file system, some in the original partition, some in ASM, and some in the cluster file system. In this way, you can easily switch the technology, or simply involve a new file system, without having to move the entire database to this file system.

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