Datasheet

Working with the ASM Instance 9
Managing the ASM Instance
Management of the ASM instance is typically done from the command-line prompt. In the
following sections, we will discuss these topics:
Starting and stopping the ASM instance
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ASM processes
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ASM disk discovery
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Redundancy, striping, and templates
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Adding an ASM disk group
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Dropping an ASM disk group
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Altering an ASM disk group
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Using the ASMCMD command-line utility
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Starting and Stopping the ASM Instance
Starting and stopping the ASM instance is pretty straightforward and much like starting
and stopping an Oracle database. Oracle knows that you are starting an ASM instance, so
it knows that when you issue the
startup command, it needs to do something a bit differ-
ent from what it would with a normal database. Exercise 1.2, shown earlier in this chapter,
walks you through starting an ASM instance.
Shutting down the ASM instance is just as easy. A
shutdown immediate, shutdown
abort
, or just a plain shutdown will do fine. If you execute a normal or immediate shutdown
command on an ASM instance, that shutdown will fail if there is any database using that
ASM instance. An error will be returned and the ASM instance will stay up. As a result,
before you shut down the ASM instance, you will need to shut down all databases using
that ASM instance.
You can perform a
shutdown abort on the ASM instance. This will cause the ASM
instance to shut down immediately and all of the associated databases will be shut down in
an inconsistent state. This will require instance recovery when the databases are restarted,
which can increase the time it takes to reopen the database. Oracle recommends that you
not use the
shutdown abort command when stopping an ASM instance.
ASM Processes
After you start your ASM instance, you will find that several of the Oracle processes you
are acquainted with will be running, such as PMON and DBWR. Additional ASM pro-
cesses will be started too. These processes include the following:
The ARB
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n process, used to perform disk group rebalance operations. There may be
one or more of these processes running.
The ASMB process manages ASM storage and provides statistics.
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The GMON process maintains disk membership in ASM disk groups.
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The KATE process performs proxy I/O to ASM metadata files when a disk is offlined.
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