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Oracle Tips by Burleson |
Oracle10g Grid Computing
with RAC
Chapter 7 - Cache Fusion and
Inter Instance Coordination
Recovery Process – Re-mastering
Resources
Scenario 1:
Neither the recovering instance (A) nor the
open instance (B) has a lock element (or it may be in NL0 mode).
This indicates that the failed instance had XL0. Therefore, SMON
acquires a lock in XL0 mode, reads the block from disk, and applies
redo changes. Therefore, the block is kept in the recovery set.
(Later, DBWR writes the recovery buffer out when recovery is
completed.)
Figure 7.8 Lock Re-Mastering – (Scenario-1)
Scenario 2:
Instance (B) has the block buffer in either XL0
mode (or SL0), but the recovering instance (A) does not have
anything. Since instance (B) is holding the lock in exclusive local
mode, it is more current than the redo stream. Therefore, no
recovery is needed. There is also no need to write this block to
disk.
Figure 7.9 Lock Remastering – (Scenario-2)
The above text is
an excerpt from:
Oracle 10g Grid & Real Application
Clusters
Oracle 10g
Grid
Computing with RAC
ISBN 0-9744355-4-6
by Mike Ault, Madhu Tumma
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