数据库Oracle10202，内存4G，调整数据库的sga_target，最初sga_target为160M，准备将其调整为2147483648 ，结果出现错误ORA-27102，经过多次试验，发现数据库在sga_target等于160M的情况下启动。

一、生成pfile,并对pfile进行修改
[oracle@CCN-BJ-4-573 dbs]$ vi initorcl.ora
orcl.__db_cache_size=50331648
orcl.__java_pool_size=4194304
orcl.__large_pool_size=4194304
orcl.__shared_pool_size=100663296
orcl.__streams_pool_size=0
*.audit_file_dest='/data/cache1/QQdatabase/product/10.2.0/db_1/admin/orcl/adump'
*.background_dump_dest='/data/cache1/QQdatabase/product/10.2.0/db_1/admin/orcl/bdump'
*.compatible='10.2.0.1.0'
*.control_files='/data/cache1/QQdatabase/product/10.2.0/oradata/orcl/control01.ctl','/data/cache1/QQdatabase/product/10.2.0/oradata/orcl/control02.ctl','/data/cache1/QQdatabase/product/10.2.0/oradata/orcl/control03.ctl'
*.core_dump_dest='/data/cache1/QQdatabase/product/10.2.0/db_1/admin/orcl/cdump'
*.db_block_size=8192
*.db_domain=''
*.db_file_multiblock_read_count=16
*.db_name='orcl'
*.db_recovery_file_dest='/data/cache1/QQdatabase/product/10.2.0/db_1/flash_recovery_area'
*.db_recovery_file_dest_size=2147483648
*.dispatchers='(PROTOCOL=TCP) (SERVICE=orclXDB)'
*.job_queue_processes=10
*.open_cursors=300
*.pga_aggregate_target=413138944
*.processes=150
*.remote_login_passwordfile='EXCLUSIVE'
*.sga_target=2147483648
*.undo_management='AUTO'
*.undo_tablespace='UNDOTBS1'
*.user_dump_dest='/data/cache1/QQdatabase/product/10.2.0/db_1/admin/orcl/udump'
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~

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"initorcl.ora" 27L, 1227C written

二、启动数据库报错
[oracle@CCN-BJ-4-573 dbs]$ sqlplus "/as sysdba"
SQL*Plus: Release 10.2.0.1.0 - Production on Fri Sep 21 14:44:30 2007
Copyright (c) 1982, 2005, Oracle. All rights reserved.
Connected to an idle instance.
SQL> startup
ORA-27102: out of memory
Linux Error: 28: No space left on device
SQL> exit
Disconnected