Increasing the size of /tmp is not a practical thing to do on a busy server, mainly because you probably won't be able to dismount /tmp because it's constantly used by various services--trying to find and kill them all is too tedius. (Plus you won't be able to do single user mode through SSH)
So what we will do here is create a whole new /tmp storage location, make a backup of the old /tmp, add the new location to fstab, reboot the server, copy everything from the backup /tmpBKP location to new location, and lastly reboot the server again.
We'll make the file container 4GB, and assign the ext2 filesystem to it--it's faster than ext3.
cp -prf /tmp /tmp.bak dd if=/dev/zero of=/var/tmpDSK bs=1024k count=4096 mkfs -t ext2 /var/tmpDSK
Check the new container filesystem
Add new container to your fstab
Add the following to your /etc/fstab and comment out the old /tmp location if present
#/var/tmpMnt /tmp ext2 loop,noexec,nosuid,nodev,rw 0 0 /var/tmpDSK /tmp ext2 loop,noexec,nosuid,nodev,rw 0 0
Reboot the Server
After server reboots
chmod -R 1777 /tmp yes | cp -rpf /tmp.bak/* /tmp
Now reboot one last time, and it should be all good.
Note: we reboot, because a lot of processes will not be able to start automatically, meaning you'd have to go through each one and manually start them--forget that nonsense.
Check the size and permissions to make sure everything is working
You should see something like this included in the results:
/var/tmpDSK 4.0G 8.8M 3.8G 1% /tmp
And that should do it..