Linux – ‘No space left on device’ on mounted NFS device

On NFS Server:

Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/xvdf2           103212320  85090308  12879132  87% /export18

On Client Server:

ip-xxxxxxxx.ap-northeast-1.compute.internal:/export18
                 103212320  85090304  12879136  87% /export18

But if I try to create file, I got this message:

touch: cannot touch `/export18/test': No space left on device

I have unmounted the volume and run fsck on it:

fsck -t ext3 /dev/xvdf2
fsck from util-linux-ng 2.17.2
e2fsck 1.41.14 (22-Dec-2010)
/dev/xvdf2 has gone 484 days without being checked, check forced.
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
/dev/xvdf2: 6553600/6553600 files (4.8% non-contiguous), 21683897/26214400 blocks

Maybe 4.8% for non-contiguous is a bit high, but… Still not able to write.

Question: What might be the reason of inability to write to the volume if there is only %87 is used?

EDIT:

Filesystem            Inodes   IUsed   IFree IUse% Mounted on
/dev/xvdf2           6553600 6553600       0  100% /export18