一台测试数据库启动时出现了这个错误。

数据库启动时报错：

[oracle@bjtest ~]$ sqlplus "/ as sysdba"

SQL*Plus: Release 9.2.0.4.0 - Production on 星期一 11月 16 08:04:00 2009

Copyright (c) 1982, 2002, Oracle Corporation.  All rights reserved.

已连接到空闲例程。

SQL> startup
ORA-27102: out of memory
Linux-x86_64 Error: 28: No space left on device

在alert文件中包含了下面的信息：

WARNING: EINVAL creating segment of size 0x0000000233400000
fix shm parameters in /etc/system or equivalent

这种错误显然是操作系统参数设置不当造成的，因为操作系统中的内存和SWAP空间是足够的。

不过系统中的内核参数设置也没有更改，一直以来数据库启动也没有报错。

检查系统参数设置：

[oracle@bjtest dbs]$ more /etc/sysctl.conf
# Kernel sysctl configuration file for Red Hat Linux
#
# For binary values, 0 is disabled, 1 is enabled.  See sysctl(8) and
# sysctl.conf(5) for more details.

# Controls IP packet forwarding
net.ipv4.ip_forward = 0

# Controls source route verification
net.ipv4.conf.default.rp_filter = 1

# Do not accept source routing
net.ipv4.conf.default.accept_source_route = 0

# Controls the System Request debugging functionality of the kernel
kernel.sysrq = 0

# Controls whether core dumps will append the PID to the core filename
# Useful for debugging multi-threaded applications
kernel.core_uses_pid = 1

# Controls the use of TCP syncookies
net.ipv4.tcp_syncookies = 1

# Controls the maximum size of a message, in bytes
kernel.msgmnb = 65536

# Controls the default maxmimum size of a mesage queue
kernel.msgmax = 65536

# Controls the maximum shared segment size, in bytes
#kernel.shmmax = 68719476736

# Controls the maximum number of shared memory segments, in pages
#kernel.shmall = 4294967296
#fs.file-max = 6553600

fs.aio-max-nr = 1048576
fs.file-max = 6815744
kernel.shmall = 2097152
kernel.shmmax = 8589934592
kernel.shmmni = 4096
kernel.sem = 250 32000 100 128
net.ipv4.ip_local_port_range = 9000 65500
net.core.rmem_default = 262144
net.core.rmem_max = 4194304
net.core.wmem_default = 262144
net.core.wmem_max = 1048586

由于数据库初始化参数设置的内存小于内核的设置，不应该导致的产生。

SQL> select 2097152 * 4096 from dual;

2097152*4096
------------
  8589934592

不过无论是SHMMAX还是SHMALL的设置，都是和内存设置相差无几，下面尝试调整SHMALL参数，设置值为4194304：

[root@bjtest ~]# sysctl -p
net.ipv4.ip_forward = 0
net.ipv4.conf.default.rp_filter = 1
net.ipv4.conf.default.accept_source_route = 0
kernel.sysrq = 0
kernel.core_uses_pid = 1
net.ipv4.tcp_syncookies = 1
kernel.msgmnb = 65536
kernel.msgmax = 65536
fs.aio-max-nr = 1048576
fs.file-max = 6815744
kernel.shmall = 4194304
kernel.shmmax = 8589934592
kernel.shmmni = 4096
kernel.sem = 250 32000 100 128
net.ipv4.ip_local_port_range = 9000 65500
net.core.rmem_default = 262144
net.core.rmem_max = 4194304
net.core.wmem_default = 262144
net.core.wmem_max = 1048586

修改后再次启动数据库，错误变成了：

[oracle@bjtest ~]$ sqlplus "/ as sysdba"

SQL*Plus: Release 9.2.0.4.0 - Production on 星期二 11月 17 01:46:54 2009

Copyright (c) 1982, 2002, Oracle Corporation.  All rights reserved.

已连接到空闲例程。

SQL> startup
ORA-27123: unable to attach to shared memory segment
Linux-x86_64 Error: 22: Invalid argument
Additional information: 1
Additional information: 884740

这个错误信息显然是指出了SHMMAX参数的设置存在问题：

[root@bjtest ~]# sysctl -p
net.ipv4.ip_forward = 0
net.ipv4.conf.default.rp_filter = 1
net.ipv4.conf.default.accept_source_route = 0
kernel.sysrq = 0
kernel.core_uses_pid = 1
net.ipv4.tcp_syncookies = 1
kernel.msgmnb = 65536
kernel.msgmax = 65536
fs.aio-max-nr = 1048576
fs.file-max = 6815744
kernel.shmall = 4194304
kernel.shmmax = 12000000000
kernel.shmmni = 4096
kernel.sem = 250 32000 100 128
net.ipv4.ip_local_port_range = 9000 65500
net.core.rmem_default = 262144
net.core.rmem_max = 4194304
net.core.wmem_default = 262144
net.core.wmem_max = 1048586

再次修改SHMMAX参数后，数据库成功启动：

SQL> startup
ORACLE 例程已经启动。

Total System Global Area 9432971568 bytes
Fixed Size                   756016 bytes
Variable Size             838860800 bytes
Database Buffers         8589934592 bytes
Redo Buffers                3420160 bytes
数据库装载完毕。
数据库已经打开。