Disk Space in linux is invisible

Article Title: questions about the invisible occupation of disk space in linux. Linux is a technology channel of the IT lab in China. Includes basic categories such as desktop applications, Linux system management, kernel research, embedded systems, and open source.

One day, I log on to a server and find the following strange situations:

: ~> Df-h

Filesystem Size Used Avail Use % Mounted on

/Dev/cciss/c0d0p1 9.9G 1.5G 7.9G 16%/

Udev 16G 164 K 16G 1%/dev

/Dev/cciss/c0d0p3 20G 261 M 19G 2%/usr/local

/Dev/cciss/c0d0p4 104G 42G 56G 43%/data

:/Data # du-sh ./*

4.0 K./corefile

4.0 K./iostat. tmp

4.0 K./log_manager

4.0 K./log_manager1

16 K./lost + found

2.2 GB./web

Clearly, the data directory is only occupied by 2 GB. Why do we see 42 GB in df?

After checking, it turned out to be a good thing for some deleted processes.

# Lsof | grep delete

Ttserver 30316 REG 2946659 7979020/data/ttserver/bin/ttserver (deleted)

Ttserver 30316 REG 70393 8028168/data // tt_feeds/log/tt. log (deleted)

Ttserver 30316 REG 42446163552 8028170/data/pet50/ttserver/tt_feeds/data/tt_feeds.tch (deleted)

The process in the data directory is not stopped, and then the file is deleted, so that the processes that are already in the memory continue to run and write to the disk ~~~

If you also find that your disk has become smaller without an end, is there the same problem?