The frequency of this check is usually configurable??”for example, every 30 seconds
??”providing control over the maximum time that a primary-node failure
will go undetected.
Time for the alternate node to execute various startup actions
The time needed for such actions (e.g., assuming control of the disks used to
store the Oracle database) may vary by system and should be determined
through testing. One important consideration is the time required for a filesystem
check. The larger the database, the larger the number of filesystems that
may have been used. When the alternate node assumes control of the disks, it
must check the state of the various filesystems on the disks.
Time for Oracle crash recovery
As we mentioned, youcan effectively control this time period using checkpoints.
Oracle provides a simple way to control recovery times using the initialization
parameter FAST_START_IO_TARGET or the more recently introduced FAST_
START_MTTR_TARGET parameter.
When the instance fails, users will typically receive some type of error message and
will typically attempt to log in again.
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