ASM

ASM(Automatic Storage Management):

Up until now all the things the application did, the OS is the ultimate owner of the data. Like without OS permissions and all this, the oracle database application cannot do any read and write in the hardware, also can't do anything else without the OS permission. Remember we need to manually give the permission to the oracle user the main user who runs the application ownership on the space in the memory from the OS side to let the application run.

Now in this scenario if the OS crashed we can't recover the data. So for that scenario Oracle give us the concept of Automatic Storage Management.

This concept is simple, the data, which was originally getting saved on the OS controlled location inside the / home directory of the Linux,

this will be saved on an extra disk which will be controlled by Oracle.

Like saving data on a pen drive or an external hard disk, if we save the data inside the computer internal secondary memory that space is controlled by OS, so if the OS crashes we can't recover the data, but if we save the data in an external memory, then we can easily plug it out and connect it somewhere else to get the data.

In ASM, there will be an extra memory space, like in terms of a Virtual Machine perspective, we were originally allocating 60GB secondary memory to the Linux OS, over that we install our oracle application, then on that we save the data of the database on that 60 GB with the non ASM database. With the ASM configured database we will give a normal memory space for the OS, then will add an extra space or an extra disk like we can connect a pen drive or other external space, this space for the ASM only.

The database instance SGA, Background process all will run by the OS, but the actual physical files, the data files, the control files, the redo log files, the archive log files, the backup files also, all will exist inside the external storage ASM Disk.