Changing shared memory size on Linux

This is useful for Postgresql and Oracle.

Look in to sysctl.

Here is a sample /etc/sysctl.conf file.

[@ ~]# cat /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 = 1

# 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 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 = 4294967295

# Controls the maximum number of shared memory segments, in pages

kernel.shmall = 268435456