About Oracle ASM Dynamic Volumes

on September 27, 2013

ASM volumes are created within an ASM disk group and are used in conjunction with the volume driver for general purpose or ASM cluster file systems. A volume can take up all or part of a single disk group, but it can exist in only one disk group. However, a disk group can contain many volumes, space permitting. When a volume is created, a device file is created in an ASM directory under the standard devices directory for your operating system. On Linux, this directory is /dev/asm.

Note that in, ASM volumes and ACFS are supported on Solaris, AIX, and Windows as well as Linux. Volumes can be managed using ASMCMD commands volcreate, voldelete, voldisable, volenable, volresize, volset, volstat, and volinfo, through ASMCA, Enterprise Manager, and using SQL commands. From a disk group’s perspective, an ASM volume is just another ASM file type, and as such, you can override the default settings for stripe size, redundancy, and intelligent placement when the volume is created. You cannot see this file through ASMCMD using the ls command; however, a select from v$asm_file in SQL on the ASM instance will show files of type ASMVOL and ASMVDRL that exist for each volume. After the volume is created, it will automatically be enabled and will be ready for use by a file system or directly by an application.

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