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Linux : Adding a Directory to the Path
The best place to add a directory to the path of a single user is to modify that user’s .bash_profile file.
To add it to all users except user root, add it to /etc/profile.
To also add it to the path of user root, add it to root’s .bash_profile file.
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Linux Oracle tuning parameter : Shutdown GUI
Modify the ‘inittab’ file to set boot level as 3:
Posted in LINUX, Oracle | June 5, 2009Linux Oracle tuning parameter : Disable Unnecessary Daemons
/sbin/chkconfig –levels 2345 sendmail off
/sbin/chkconfig sendmail off
Linux Oracle tuning parameter : Tune TCP
To view current TCP settings, run command:
sysctl net.ipv4.tcp_keepalive_time
net.ipv4.tcp_keepalive_time = 7200 // 2 hours
where net.ipv4.tcp_keepalive_time is a TCP tuning parameter.
To set a TCP parameter to a value, run command:
sysctl -w net.ipv4.tcp_keepalive_time=1800
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Linux vs. Oracle Tuning, Error : ORA-00845: MEMORY_TARGET not supported on this system
The ORA-00845:can arises for the following two reasons on linux system.
1)If the shared memory which is mapped to /dev/shm directory is less than the size of MEMORY_TARGET or MEMORY_MAX_TARGET.
or,
2)If the shared memory is not mapped to /dev/shm directory.
Make sure /dev/shm is properly mounted. You can see it by,
df -h
Filesystem Size Used Avail Use% Mounted on
…
shmfs 30G 15G 15G 30% /dev/shm
As a root user,
mount -t tmpfs shmfs -o size=30g /dev/shm
In order to make the settings persistence so that it will affect after restarting machine add an entry in /etc/fstab similar to the following:
shmfs /dev/shm tmpfs size=13g 0
Posted in LINUX, Oracle | June 5, 2009Linux Oracle tuning parameter : ulimits
To view current settings, run command:
ulimit -a
To set it to a new value for this running session, which takes effect immediately, run command:
ulimit -n 8800
ulimit -n -1 // for unlimited; recommended if server isn’t shared
Alternatively, if you want the changes to survive reboot, do the following:
- Exit all shell sessions for the user you want to change limits on.
- As root, edit the file /etc/security/limits.conf and add these two lines toward the end:
oracle soft nofile 16000
oracle hard nofile 20000
** the two lines above changes the max number of file handles – nofile – to new settings.
- Save the file.
- Login as the user1 again. The new changes will be in effect.
Linux Oracle tuning parameter : Message queues
To view current settings, run command:
more /proc/sys/kernel/msgmni
more /proc/sys/kernel/msgmax
To set it to a new value for this running session, which takes effect immediately, run command:
echo 2048 > /proc/sys/kernel/msgmni
echo 64000 > /proc/sys/kernel/msgmax
Linux Oracle tuning parameter : shmmax and shmall
maximum amount of memory = shmall * pagesize
where pagesize = getconf PAGE_SIZE and shmall = cat /proc/sys/kernel/shmall
Linux Oracle tuning parameter : Semaphores
To view current settings, run command:
more /proc/sys/kernel/sem
250 32000 32 1024
To set it to a new value for this running session, which takes effect immediately, run command:
echo 500 512000 64 2048 > /proc/sys/kernel/sem
Parameters meaning:
SEMMSL – semaphores per ID
SEMMNS – (SEMMNI*SEMMSL) max semaphores in system
SEMOPM – max operations per semop call
SEMMNI – max semaphore identifiers
Linux Oracle tuning parameter : Shared Memory
To view current settings, run command:
more /proc/sys/kernel/shmmax
To set it to a new value for this running session, which takes effect immediately, run command:
echo 268435456 > /proc/sys/kernel/shmmax
To set it to a new value permanently (so it survives reboots), modify the sysctl.conf file:
…
kernel.shmmax = 268435456