Datasheet

Working with the ASM Instance 25
the rebalance operation has completed. The default is nowait, which will cause the opera-
tion to be synchronous in nature. You can check the status of the rebalance operation using
the
V$ASM_OPERATION view during asynchronous rebalance operations. If you use the wait
parameter and you want to convert the operation to an asynchronous operation, you can
simply press Ctrl+C on most platforms and an error will be returned along with the SQL
prompt. The rebalance operation will continue, however.
If you do not use the
power parameter during a manual rebalance operation, or if an
implicit rebalance operation is occurring (because you are dropping a disk, for example), you
can affect the power of that rebalance operation by dynamically changing the
ASM_POWER_
LIMIT
parameter to a higher value with the alter system command.
Finally, you can also use the
rebalance parameter along with the power parameter when
adding, dropping, or resizing disks within a disk group, as shown in this example:
alter diskgroup cooked_dgroup1 resize all rebalance power 5;
Manually Mounting and Unmounting an ASM Disk Group
If an ASM disk group is not assigned to the ASM_DISKGROUPS parameter, or if the disk group
is unmounted for some other reason, you will need to mount the ASM disk group. You can
use the
alter diskgroup command with the mount clause to mount the disk group.
Additionally, if you need to dismount an ASM disk group, you can use the
alter
diskgroup
command. Here are some examples:
alter diskgroup sp_dgroup2 dismount;
alter diskgroup sp_dgroup2 mount;
Note that when you dismount a disk group, that disk group will be automatically removed
from the
ASM_DISKGROUPS parameter if you are using an spfile. This means that when ASM is
restarted, that disk group will not be remounted. If you are using a regular text parameter file,
you will need to remove the disk group manually (assuming it’s in the parameter file to begin
with) or ASM will try to remount the disk group when the system is restarted.
Checking the Consistency of a Disk Group
On occasion you might wonder if there is some problem with an ASM disk group, and you
will want to check the consistency of the ASM disk group metadata. This need might arise
because of an error that occurs when the ASM instance is started or as the result of an Oracle
database error that might be caused by some ASM corruption. To perform this check, simply
use the
alter diskgroup command with the check all parameter, as shown in this example:
alter diskgroup sp_dgroup2 check all;
When you execute the alter diskgroup check all command the results are written to
the alert log of the instance. ASM will attempt to correct any errors that are detected.
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