Run out of inodes?

[Samuel Granjeaud]

Hi,

Sorry if the answer is obvious, but I didn't find any clear answer after 
googling.

I have a XFS system of 18T over LVM. Recently, I could not create new 
files or directories.

# mkdir tempo
mkdir: cannot create directory `tempo': No space left on device

After deleting a few files, this command runs successfully.

So I think that the system runs out of something, inodes I guess.

But the df diagnosis does not enlight it: only 1% used.

# df -ht xfs
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/vg1_backup-backup
                        18T   12T  6.6T  63% /mnt/vg1_backup/backup
# df -it xfs
Filesystem            Inodes   IUsed   IFree IUse% Mounted on
/dev/mapper/vg1_backup-backup
                      18874040320  530042 18873510278    1% 
/mnt/vg1_backup/backup

So what is wrong? How should I solve the problem?

I read about xfs_grow -m, but I am not sure if it could help.
Of course, I rebooted the system before my trials.

Best regards,
Samuel