Solaris du and df result are mismatch but fix by ftp

I have a filesytem which share to user via NFS. And some users upload files through FTP to this FS。

The filesystem type is Veritas VXFS. I upgraded Veritas from 5.1 to 6.1.1 recently. After that the df -h reports the disk usage keep increasing, but du -sh shows the usage is about 500M.

1 df -h /dev/vx/dsk/rawdg/rawdatavol 35G 1.1G 35G 3% /rawdata 2 du -sh 517M /rawdata

Users ofter upload data to /rawdata/data1. I used fuser -c and lsof but no process kept accessing this directory. If I ftp to /rawdata/data1 and excute ls, then the df -h reports the filesystem used is about 600M after a few seconds.

I tested this case several times and the ftp was the best solution so far. Any suggestion?

Thanks