Tuning the Cluster Interconnect - Expert Oracle RAC Performance Diagnostics and Tuning - page 478

Step 9
A total of 17 days after the fix, there are no lost blocks in the production environment. The output does show a block
corruption entry for instance one. Such occasional errors can be due to several unknown reasons and can be safely
ignored. Oracle will retransmit the block back to the requestor:
Script: MVRACPDnTap_raclostblocks.sql
SELECT
A1.INST_ID ,
A3.INSTANCE_NAME,
A3.HOST_NAME,
A3.STARTUP_TIME,
ROUND (SYSDATE - STARTUP_TIME) "Days",
ROUND ((SYSDATE - STARTUP_TIME) *24) "Hours",
A1.VALUE "BLKL",
A1.VALUE/(ROUND((SYSDATE - STARTUP_TIME) *24)) "Perhr",
A2.VALUE "BLKC"
FROM GV$SYSSTAT A1,
GV$SYSSTAT A2,
GV$INSTANCE A3
WHERE A1.NAME = 'gc blocks lost'
AND A2.NAME = 'gc blocks corrupt'
AND A1.INST_ID = A2.INST_ID
AND A1.INST_ID = A3.INSTANCE_NUMBER
ORDER BY 1;
Instance Instance Blocks Blocks
Instance Name Startup Time Up Days Lost Corrupt
-------- ---------- ------------------ -------- -------- --------
1 MVP1 16-OCT-10 06:00:17 17 0 1
2 MVP2 16-OCT-10 06:00:18 17 0 0
3 MVP3 16-OCT-10 06:00:17 17 0 0
4 MVP4 16-OCT-10 06:00:19 17 0 0
5 MVP5 16-OCT-10 06:00:19 17 0 0
Data Dictionary Views to Monitor Cluster Interconnect
Like any feature of Oracle, the interconnect and RAC-related features can be monitored by a set of views. In this
section, we discuss some of the important views that would help monitor and troubleshoot issues.
GV$DYNAMIC_REMASTER_STATS
This view gives the object re-master statistics from the time the object re-master has been initiated to its completion.
All tasks involved in the process are recorded in the appropriate columns. This helps to determine how much of
network traffic occurs during re-mastering activity. Using the steps illustrated to manually relocate an object master in
Chapter 13, the individual re-master latencies can be obtained.
During peak network usage, re-mastering can also be delayed, which would indirectly affect the overall
performance of the RAC environment. Apart from the delay during high interconnect activity, the re-mastering
operation can also be impacted by high CPU utilization by the LMS process.