Accessing Oracle ASM Files with the XML DB Virtual Folder
Oracle ASM files and directories can be accessed through a virtual folder in the XML DB repository. The repository path to the virtual folder is /sys/asm. The folder is virtual because its contents do not actually reside in the repository; they exist as normal Oracle ASM files and directories. For example, /sys/asm provides a means to access and manipulate the Oracle ASM files and directories with programmatic APIs such as the DBMS_XDB package and with XML DB protocols such as FTP and HTTP/WebDAV. You can also use the ASMCMD cp command to copy files. See "cp".
A typical use for this capability might be to view /sys/asm as a Web Folder in a graphical user interface (with the WebDAV protocol), and then copy a Data Pump dumpset from an Oracle ASM disk group to an operating system file system by dragging and dropping.
You must log in as a user other than SYS and you must have been granted the DBA role to access /sys/asm with XML DB protocols. For additional information about the /sys/asm folder, refer to "Inside /sys/asm".
For security reasons, FTP is disabled, by default. This is because the IETF FTP protocol specification requires that passwords be transmitted in clear text. Disabling is done by configuring the FTP server port as zero (0). To enable FTP, set the ftp-port parameter to the FTP port to use, such as 2100.
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Oracle XML DB Developer's Guide for information about Oracle XML DB, including additional ways to configure port numbers for the XML DB protocol servers
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Oracle Database PL/SQL Packages and Types Reference for information about the
DBMS_XDBpackage
Inside /sys/asm
The Oracle ASM virtual folder is created by default during XML DB installation. If the database is not configured to use Oracle ASM, the folder is empty and no operations are permitted on it.
The Oracle ASM virtual folder contains folders and subfolders that follow the hierarchy defined by the structure of an Oracle ASM fully qualified file name. Figure 5-1 illustrates an example of this hierarchy, which for simplicity, excludes directories created for aliases.
The folder /sys/asm contains one subfolder for every mounted disk group, and each disk group folder contains one subfolder for each database that uses the disk group. In addition, a disk group folder might contain files and folders corresponding to aliases created by the administrator. Continuing the hierarchy, the database folders contain file type folders, which contain the Oracle ASM files.
Figure 5-1 Hierarchical Structure of Oracle ASM Folders in an XML DB Installation
Description of "Figure 5-1 Hierarchical Structure of Oracle ASM Folders in an XML DB Installation"
The following are usage restrictions on /sys/asm:
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You cannot create hard links to existing Oracle ASM files or directories with APIs such as
DBMS_XDB.LINK. -
You cannot rename (move) an Oracle ASM file to another disk group or to a directory outside Oracle ASM.
You can use the directory /sys/asm for storing the names of disk groups. You cannot store other files in this directory. Within the disk group directories under /sys/asm, such as /sys/asm/DATA, you can only store database files in these sub-directories. Oracle ASM rejects attempts to store non-database files in these directories.