测试环境安装19c,内存不太够，需要降低asm 内存参数，但是发现调整后未生效？
总结下，oracle 11.2.0.4 >=oracle 建议是asm内存是最低1G，如果配置小于这个数值，会自动调整为1G大小！
ASM>
NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ memory_max_target big integer 1076M memory_target big integer 1076M
SQL> alter system set memory_max_target=400m scope=spfile sid='+ASM1';
SQL> alter system set memory_target=400m scope=spfile sid='+ASM1';
重启ASM实例后,Memory_target参数还是这么大？ 也没有报错！
$ srvctl stop asm -n d1 -stopoption IMMEDIATE -force
$ srvctl start asm -n d1
仔细阅读ASM alert启动日志，发现存在 SGA ??? 1021M???
Using parameter settings in server-side spfile +OCR/ora19c-cluster/ASMPARAMETERFILE/registry.253.1036510257
System parameters with non-default values:
large_pool_size = 12M
memory_target = 1G
memory_max_target = 1G
2020-04-01T06:47:45.260548-07:00
Domain name: user.slice
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Per process system memlock (soft) limit = UNLIMITED
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Expected per process system memlock (soft) limit to lock
instance MAX SHARED GLOBAL AREA (SGA) into memory: 1021M
再次查询参数SGA大小！
sga_max_size big integer 1G
调整sga参数大小后，再次重启OK
修改！
SQL> alter system set sga_max_size=300m scope=spfile sid='+ASM1';
$ srvctl stop asm -n d1 -stopoption IMMEDIATE -force
$ srvctl start asm -n d1
还是不行 NONONO
2020-04-01T07:53:55.490561-07:00
Instance shutdown complete (OS id: 56638)
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WARNING: Minimum MEMORY_TARGET required on ASM instance is 1073741824
* instance_number obtained from CSS = 1, checking for the existence of node 0...
* node 0 does not exist. instance_number = 1
Starting ORACLE instance (normal) (OS id: 81021)
2020-04-01T07:54:09.987809-07:00
****************************************************
/dev/shm will be used for creating SGA
Large pages will not be used. Only standard 4K pages will be used
****************************************************
Default and Minimum MEMORY_TARGET & MEMORY_MAX_TARGET Value for ASM 11.2.0.4 and Onwards (Doc ID 1982132.1)