crontab -- No space left on device

Question

crontab -e
/tmp/crontab.KxTGwK: No space left on device

and

df
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/sda3            955486988 157545404 749405676  18% /
tmpfs                 37042680         0  37042680   0% /dev/shm
/dev/sda1               253871     89090    151674  38% /boot
/usr/tmpDSK            4128448    338068   3580668   9% /tmp

however I get this with df -i

df -i
Filesystem            Inodes   IUsed   IFree IUse% Mounted on
/dev/sda3            60669952 3809723 56860229    7% /
tmpfs                9260670       1 9260669    1% /dev/shm
/dev/sda1              65536      53   65483    1% /boot
/usr/tmpDSK           262144  262144       0  100% /tmp

So I can clean /tmp our with rm -rf /tmp/* but what is the difference between the two df's? and how is it /tmp is full yet not?

Solution 1

df -h shows block usage; df -i shows inode usage.

You already used 100% of the inodes (262144 of 262144 ) so it means that you can't create new files there.

Solution 2

Its "meta-data section" is full, data isn't. YMMW, but it's quite common to use Tmpfs for /tmp, so you can overcome this using its mount option nr_inodes:

The tmpfs mount options for sizing ( size, nr_blocks, and nr_inodes)

Comments

[Admin]

A gazillion empty files? If I understand this correctly, it means that not all of the space is used up, but there's also a limit on the number of files you can have on the filesystem (the inodes). Even though there may be space for more data on the file system, you can't create more files because you don't have any inodes left. Is that right?

[Tiffany Walker]

So is that the major difference between the common /tmp and /dev/shm? (never really understood /dev/shm)

[poige]

/tmp can be whatever — it can be a sub-dir on root filesystem or can be mounted anything else, including mentioned Tmpfs. /dev/shm is just another mount point.

[Alan Kuras]

@Ghodmode yep You understand this correctly