SQL> show sga
Total System Global Area 6.1189E+10 bytes
Fixed Size 830456 bytes
Variable Size 3.4175E+10 bytes
Database Buffers 2.7011E+10 bytes
Redo Buffers 1847296 bytesYou might be confused about the memory allocation message during startup. Here is a simple decomposition of SGA major components. Please see the statement below: (The credit goes to AskTom)
SQL> compute sum of bytes on pool;
SQL> break on pool skip 1;
SQL> select pool, name, bytes from v$sgastat order by pool, name;
POOL NAME BYTES
----------- -------------------------- ----------
java pool free memory 33554432
*********** ----------
sum 33554432 (Variable Size 1/3)
large pool free memory 134217728
*********** ----------
sum 134217728 (Variable Size 2/3)
shared pool 1M buffer 1056768
AQ Propagation Scheduling 16000
BRANCH TABLE SEGMENTED AR 276576
Checkpoint queue 30750720
DML lock 1413080
ENQUEUE STATS 19968
FileIdentificatonBlock 562016
FileOpenBlock 15431456
KGK heap 16600
KGLS heap 487632
KQR L PO 353312
KQR M PO 175168
KSXR SGA 22720
KSXR large reply queue 167624
KSXR pending messages que 853952
KSXR pending reply queue 98680
KSXR receive buffers 1034000
KTC latches 15128
LRMPD SGA Table 94976
MTTR advisory 948248
PL/SQL DIANA 591080
PL/SQL MPCODE 761136
PLS non-lib hp 2088
Parameter Table 27232
SEQ S.O. 238320
SQL Memory Manager Base W 19296
SYSTEM PARAMETERS 127016
TXN TABLE SEGMENTED ARRAY 164352
Temporary Tables State Ob 389736
UNDO INFO HASH 58240
UNDO INFO SEGMENTED ARRAY 325056
UNDO STAT INFO 52416
alter system errs: kspnfy 110592
branch 591488
channel context areas 23760
channel handle 391504
character set memory 44024
character set object 274528
constraints 412608
db_block_hash_buckets 111966800
db_files 243648
db_handles 1740000
dictionary cache 3229952
distributed_transactions- 24656
dlo fib struct 32032
dummy 135088
enqueue 2772720
enqueue resources 1015840
enqueue_hash 160560
errors 14968
event statistics per sess 18628680
file # translation table 48056
fixed allocation callback 2992
free memory 1047530520
granule hdrs 14336
java static objs 30768
joxs heap init 4240
kcbl seq io throughput 16000
kghx free lists 65416
kglsim hash table bkts 4194304
kglsim heap 266240
kglsim object batch 213696
kglsim pin list arr 43632
kglsim sga 137544
krvxrr 253056
ksm_file2sga region 370496
ksuloi: long op statistic 124000
ktlbk state objects 975520
latch nowait fails or sle 67136
latch wait list latches 15872
library cache 4549240
log_buffer 57376
log_checkpoint_timeout 12328
log_simultaneous_copies 25344
message pool freequeue 761808
messages 312000
miscellaneous 6901880
network connections 133584
parameters 3192
process group array 21904
processes 1920000
qmps connections 701720
replication session stats 503120
session param values 490176
sessions 4475120
set_descriptor_array 310272
sim hash latches 126976
sim memory hea 26746856
sim trace entries 2359296
sql area 1708184
table definiti 112
trace buffer 311296
trace events array 80000
transaction 3017304
trigger defini 544
trigger inform 648
trigger source 168
txncallback 300608
work area tabl 8320
xssinfo 45608
*********** ----------
sum 1308622848 (Variable Size 3/3)
buffer_cache 2.7011E+10 (Database Buffers)
fixed_sga 830456 (Fixed Size)
log_buffer 1836032 (Redo Buffers)
*********** ----------
sum 2.7014E+10
105 rows selected.In short, Variable Size is a summation of all "pool" including java pool, large pool and shared pool.