Linux How-To

Finding Your Linux Release

This you can get from a static file redhat-release located in the /etc  directory

view /etc/redhat-release
Red Hat Enterprise Linux AS release 4

NFS mounting on Linux

Supposing you want to mount a u01/sam on Node_A to Node_B

Configurations on Node_A
edit the /etc/exports file
vi /etc/exports
add the filesystem to mount
/u01/sam ro Node_B

you can either use the option ro which means read only or in case you wish to allow node_b to write into the filesystem use  the rw option which is read writeable.

The change in exports file takes effect only after the restart of your NFS service daemon. use the service command to do  that.

# service nfs restart
Shutting down NFS mountd:                                  [  OK  ]
Shutting down NFS daemon:                                  [  OK  ]
Shutting down NFS quotas:                                  [  OK  ]
Shutting down NFS services:                                [  OK  ]
Starting NFS services:                                     [  OK  ]
Starting NFS quotas:                                       [  OK  ]
Starting NFS daemon:                                       [  OK  ]
Starting NFS mountd:                                       [  OK  ]

Configuration for Node_B

On Node_B simply create the mount point to hold the shared file system and mount it using the mount command.

#mkdir sam
#mount -t nfs Node_A:/u01/sam /sam

Setting Kernel Parameters

Most oracle products require certain kernel parameters to be set as a pre requisite for installation. Common kernel parameters include parameters for shared memory .

The /etc/sysctl.conf file takes care of your kernel parameters.
#vi /etc/sysctl.conf
kernel.shmmax = 2147483648
kernel.shmmni = 128
kernel.shmall = 2097152
kernel.sem = 250 32000 100 128
fs.file-max = 65536
net.ipv4.ip_local_port_range = 1024 65000

However changes made to this file take effect only after the next reboot.

The sysctl command can be used to set the kernel parameter at runtime in linux.

sysctl -w kernel.shmmax=2147483648

You must however make the change in the /etc/sysctl.conf so that it is permanent.

Increasing the Swap space at runtime

Imagine this, you start the OUI and your pre installation check fails due to insufficient swap space. Now I agree that you  got to check all this before starting the installation but just in case you missed it. You could always increase it on the  fly.

Check the memory on your server

# free -m
             total       used       free     shared    buffers     cached
Mem:          8117       3204       4913          0         77       2648
-/+ buffers/cache:        478       7639
Swap:          101          0        101

Now say you need to increase it by 500 MB for your server, first locate a place you can spare this 500 MB in my case i found  it in /u01

Use the dd command to create a swapfile

#cd /u01
# dd if=/dev/zero of=swapfile bs=1024 count=512000
512000+0 records in
512000+0 records out
# ls -ltr
drwx------   2 root   root     16384 May  1  2006 lost+found
-rw-r--r--   1 root   root 524288000 Nov 28 13:58 swapfile

Next issue the following two commands

# mkswap swapfile
Setting up swapspace version 1, size = 524283 kB
# swapon swapfile

Now check you memory again

# free -m
             total       used       free     shared    buffers     cached
Mem:          8117       2176       5941          0         45       1975
-/+ buffers/cache:        155       7962
Swap:          601          0        601

Bingo! here is your increased SWAP.

To make this change permanent add the line in your etc/fstab
/u01/swapfile swap swap defaults 0 0