CWTEA NETORA-27125：unabletocreatesharedmemorysegment的解决
⽅法
在某些操作系统上，当启动数据库或者创建数据库时都可能出现ORA-27125错误，我在Oracle Linux 6上安装Oracle 10.2.0.1，创建数据库时就遇到了这个错误。 这个错误的解决就是修改 /proc/sys/vm/hugetlb_shm_group ⽂件。
以下是⽼杨提到过的⼀个问题，解决⽅法相同：
血管集束征
帮客户解决⼀个Linux上数据库⽆法启动的问题。
客户的Linux 5.6 x86-64环境，安装数据库后，启动数据库报错：ORA-27125。
Oracle⽂档上关于ORA-27125错误的描述为：
ORA-27125: unable to create shared memory segment
Cause: shmget() call failed
Action: contact Oracle support
查询了⼀下，发现问题和linux上的hugetbl有关。
解决⽅法也很简单，⾸先检查oracle⽤户的组信息：
苏州蓝缨学校[oracle@yans1 ~]$ id oracle
uid=500(oracle) gid=502(oinstall) groups=502(oinstall),501(dba)
[oracle@yans1 ~]$ more /proc/sys/vm/hugetlb_shm_group
下⾯⽤root执⾏下⾯的命令，将dba组添加到系统内核中：
# echo 501 > /proc/sys/vm/hugetlb_shm_group
然后启动数据库，问题消失。
红白歌会2016但以上这种⽅式在重启操作系统后失效， /proc/sys/vm/hugetlb_shm_group⼜变为了0，建议采⽤以下⽅式解决：
加⼊vm.hugetlb_shm_group = 501 到/f中来解决：
# vi /f
加⼊如下的内容，其中501为dba组号，需要根据你实际的情况进⾏改变。
vm.hugetlb_shm_group = 501财会学习
# sysctl -p
那么hugetlb_shm_group组是什么呢？以下是解释：
hugetlb_shm_group contains group id that is allowed to create SysV shared memory segment using hugetlb page
这⾥反复提到了HugePage，以下是关于HugePage的说明和解释：科技创新
When a process uses some memory, the CPU is marking the RAM as used by that process. For efficiency, the CPU allocate RAM by chunks of 4K bytes (it's the default value on many platforms). Those chunks are named pages. Those pages can be swapped to disk, etc.
Since the process address space are virtual, the CPU and the operating system have to remember which page belong to which process, and where it is stored. Obviously, the more pages you have, the more time it takes to find where the memory is mapped. When a process uses 1GB of memory, t
hat's 262144 entries to look up (1GB / 4K). If one Page Table Entry consume 8bytes, that's 2MB (262144 * 8) to look-up.
Most current CPU architectures support bigger pages (so the CPU/OS have less entries to look-up), those are named Huge pages (on Linux), Super Pages (on BSD) or Large Pages (on Windows), but it all the same thing.
豫公网安备41160202000603
站长QQ:729038198
关于我们
投诉建议