Datasheet
32
Chapter 1
Using Oracle ASM
ASM Files
ASM files are created in a number of different ways; for example, when you execute the
create tablespace command and you indicate that the resulting datafile(s) should be
stored in an ASM disk group, the result will be the creation of ASM files in that ASM
disk group.
A goodly number of Oracle file types can be stored in ASM, including datafiles, control
files, redo logs, and archived redo logs. There are some Oracle files that cannot be stored in
an ASM group. These are mostly the administrative files like trace files, the alert log, and
so on.
ASM Filename Types
When a file is created on an ASM disk, the filename is generated by ASM. There is a num-
ber of different kinds of ASM filename types:
Fully qualified ASM filenames
Numeric ASM filenames
Alias ASM filenames
Alias filenames with templates
Incomplete filenames
Incomplete filenames with templates
Let’s look at each of these types in a bit more detail.
Fully Qualified ASM Filenames
The full filename is known as the fully qualified ASM filename. Here is an example of a
fully qualified ASM filename:
+sp_dgroup2/mydb/controlfile/Current.56.544956473
The naming format for a fully qualified ASM filename is as follows:
The
+group is listed (in our case, +sp_dgroup2). Note that the + indicates the root of
the ASM filename.
The database name (in our case
mydb).
The file type (in our case, this is a control file).
Next we have the start of the actual ASM file. First we have the file type flag (in our
case, Current). This provides additional information on the file type in question.
In this case, this is a current control file, as opposed to a control-file backup, which
would be listed as
backup.
Finally we have two numbers delineated by a period (56.544956473), which represent
the file number and an incarnation number. These two numbers combined guarantee
that the ASM filename will be unique from any other ASM filename on the system.
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