I'm setting up a server on linode.com. I have 48G ssd. I put a lot of small files. The system is showing me a message saying No spece left, but by using df -h command, I see I still have 19GB unused. Then I used df -i and found that no inode is available anymore. The total number of inode is 3056000. How can I increase this limit?
IMHO you can not change the inode limit after creating the filesystem for many filesystems.
You can set the number of inodes by using the -N switch of mkfs. Before recreating the filesystem you can check the default calculation of inodes by using the -n switch.
consult this answer: How to store one billion files on ext4? for more information.