Database Reference
In-Depth Information
Current Max Initial
RESOURCE_NAME Util Util Alloc Limit
------------------------------ ---------- ---------- --------------- ----------
ges_ress 123090 689253 131128 UNLIMITED
ges_locks 91215 524188 293045 UNLIMITED
gcs_resources 755053 1167954 4135261 4135261
gcs_shadows 823219 874225 4135261 4135261
If you have access and license to performance metrics stored in AWR (Automatic Workload Repository), you can
review the growth and shrink of these areas over a period using the code listed in Listing 11-1.
Listing 11-1.
History of SGA Allocations for RAC-Specific Allocations
select
to_date(to_char(trunc(begin_interval_time), 'DD-MON-YYYY'), 'DD-MON-YYYY') DAY,
instance_number,
trunc(max(bytes/1024/1024),2) sz_MB
from
(select begin_interval_time, s.instance_number, sum(bytes) bytes
from
dba_hist_sgastat g, dba_hist_snapshot s
where (name like '%ges%' or name like '%gcs%')
and trunc(begin_interval_time) >= sysdate -30
and s.snap_id = g.snap_id
and s.instance_number = g.instance_number
group by begin_interval_time, s.instance_number
)
group by
to_date(to_char(trunc(begin_interval_time), 'DD-MON-YYYY'), 'DD-MON-YYYY'),
instance_number
order by 1
/
DAY INSTANCE_NUMBER SZ_MB
--------------- --------------- ----------
...
22-SEP-12 1 1347.56
22-SEP-12 2 599.44
22-SEP-12 3 1358.17
To accommodate the increase in RAC-specific memory allocations, you should consider increasing the size of
shared pool (shared_pool_size parameter) when you convert the database from single instance to a RAC database.
2
Along the same line of reasoning, you should consider increasing the size of shared pool if you increase buffer cache
size to accommodate the increase in GCS allocation size.
2
Required increase in shared_pool_size depends upon your SGA size, current shared_pool size, Database software version, etc.
However, a 20% increase in single-instance shared_pool _size and a 10% increase in buffer cache is a good preliminary design.
Sandesh Rao, Director of RAC Assurance Team, agrees with this recommendation.
