Tuning Global Cache - Expert Oracle RAC Performance Diagnostics and Tuning - page 432

Here is a sample output (formatted for inclusion in the book):

Pin Flush Flush Write Write
100-1000 10-100 100-1000 10-100 100-1000
In ms ms ms ms ms EVICTDC WRITEDC
--- -------- -------- -------- -------- -------- -------- --------
1 0 9 207 932 82 484071 11802
2 1 5 189 1551 150 353875 8552
3 0 7 204 6469 396 420054 16367
4 0 9 161 2704 126 840889 10347
5 0 6 272 1991 204 256154 18344
6 0 1 651 35092 12378 227796 903243
7 1 2 843 62992 8090 450609 413363
8 0 1 589 30706 3096 236854 280688

Historical data for this view is maintained in DBA_HIST_CURRENT_BLOCK_SERVER.

GV$GES_CONVERT_LOCAL
This view displays statistics for local GES enqueue operations and records average convert times, count information,
and timed statistics for global enqueue requests for consistent read requests/operations. It is a useful view to determine
the type of locks conversions (listed in Table 13-3 ) that happen locally on the instance or on the remote servers.

Table 13-3. Lock Conversion Types

Conversion Type Description

NULL -> SS NULL mode to subshared mode.

NULL -> SX NULL mode to shared exclusive mode.

NULL -> S NULL mode to shared mode occurs when a block is selected by a query. The block may or

may not be present in the buffer cache. If a current copy of the block is in the cache, then
only a lock conversation takes place, and the lock is not read from disk again.

NULL -> SSX NULL mode to subshared exclusive mode.

NULL -> X NULL mode to exclusive mode. This conversion occurs when reading a block into the SGA

for DML operation (INSERT, UPDATE, DELETE).

SS -> SX Subshared mode to shared exclusive mode.

SS -> S Subshared mode to shared mode.

SS -> SSX Subshared mode to subshared exclusive mode.

SS -> X Subshared mode to exclusive mode.

SX -> S Shared exclusive mode to shared mode.

SX -> SSX Shared exclusive mode to subshared exclusive mode.

SX -> X Shared exclusive mode to exclusive mode.

S -> SX Shared mode to shared exclusive mode.

S -> X Shared mode to exclusive mode occurs when a block is read into the SGA by a SELECT

statement, and then a DML statement is issued against the same block.

SSX -> X Subshared exclusive to exclusive mode.