标题: ORA-00845: MEMORY_TARGET not supported on this system [打印本页] 作者: mahan 时间: 2024-1-5 17:16 标题: ORA-00845: MEMORY_TARGET not supported on this system 1 问题
Oracle 11G 中出现了memory_target 参数，用以实现自动 内存管理 。这个参数的实际使用 需要/dev/shm 空间的支持，如果/dev/shm的空间小于memory_target的值 ，就会遇到如下 错误:
SQL> startup
ORA-00845: MEMORY_TARGET not supported on this system
alert 日志中的信息类似如下：
WARNING: You are trying to use the MEMORY_TARGET feature. This feature requires the /dev/shm file system to be mounted for at least 53687091200 bytes. /dev/shm is either not mounted or is mounted with available space less than this size. Please fix this so that MEMORY_TARGET can work as expected. Current available is 33619214336 and used is 26345472 bytes. Ensure that the mount point is /dev/shm for this directory.
memory_target needs larger /dev/shm
2 分析
查看关于错误的描述 很多时候, Oracle 错误代码后面的提示信息会给我们充足的信息。但是有些时候的信息也会让我们有点儿懵圈。比如本次我们需要了解的错误。 按照英文的意思，就是当前操作系统不支持使用memory_target参数。但是我们知道, 在当前Linux操作系统中，这个参数是支持的。所以肯定是有其他原因。关于ORACLE错误 更详细的信息，可以使用oerr ora errcode 。下面是本次相关错误的详细信息提示:
[user@hostname ~]$ oerr ora 845
00845, 00000, "MEMORY_TARGET not supported on this system"
// *Cause: The MEMORY_TARGET parameter was not supported on this operating system or /dev/shm was not sized correctly on Linux.
// *Action: Refer to documentation for a list of supported operating systems. Or, size /dev/shm to be at least the SGA_MAX_SIZE on each Oracle instance running on the system.
根据提示Cause:/dev/shm was not sized correctly on Linux. 我们知道了此错误的原因，原来是因为/dev/shm 的大小有问题。 而根据提示Action: size /dev/shm to be at least the SGA_MAX_SIZE…. 这里我们知道了。/dev/shm 的大小至少应该大于 sga_max_size的值。