为什么提示这个错？

369D049B   0719175610 I O SYSPFS         UNABLE TO ALLOCATE SPACE IN FILE SYSTEM
was02t:/#errpt -aj 369D049B
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LABEL:          JFS_FS_FULL
IDENTIFIER:     369D049B

Date/Time:       Mon Jul 19 17:56:57 2010
Sequence Number: 1171
Machine Id:      00CFDA6E4C00
Node Id:         was02t
Class:           O
Type:            INFO
Resource Name:   SYSPFS

Description
UNABLE TO ALLOCATE SPACE IN FILE SYSTEM

Probable Causes
FILE SYSTEM FULL

        Recommended Actions
        USE FUSER UTILITY TO LOCATE UNLINKED FILES STILL REFERENCED
        INCREASE THE SIZE OF THE ASSOCIATED FILE SYSTEM
        REMOVE UNNECESSARY DATA FROM FILE SYSTEM

Detail Data
MAJOR/MINOR DEVICE NUMBER
000A 001E
FILE SYSTEM DEVICE AND MOUNT POINT
/dev/work, /work

/dev/work        4194304   2465328   42%      837     1% /work
明显/work所在文件系统只使用了42%，那为什么还会报文件系统空间不足呢？？？？？