我正在使用 Ubuntu Linux 16。我的磁盘空间不足......
[rails@server ~]$ df -h /
Filesystem Size Used Avail Use% Mounted on
/dev/simfs 30G 29G 1.5G 96% /
但我不明白的是，当我得到“/”目录的总大小时，它显示小于 29G ...
[rails@server ~]$ sudo du -sh /
du: cannot access ‘/proc/883/task/883/fd/4’: No such file or directory
du: cannot access ‘/proc/883/task/883/fdinfo/4’: No such file or directory
du: cannot access ‘/proc/883/fd/4’: No such file or directory
du: cannot access ‘/proc/883/fdinfo/4’: No such file or directory
4.5G /
这里发生了什么？更重要的是，我如何弄清楚所有这些神秘的磁盘空间都被用在了哪里？
编辑：
按照 GracefulRestart 的要求输出...
[rails@server ~]$ sudo lsof -nP 2>&1 | grep 'deleted'
postmaste 443 postgres mem REG 144,4 147159237 (deleted)/dev/zero (stat: No such file or directory)
postmaste 443 postgres mem REG 144,4 0 (deleted)/VE20428-SYSV0052e2c1 (stat: No such file or directory)
postmaste 469 postgres mem REG 144,4 147159237 (deleted)/dev/zero (stat: No such file or directory)
postmaste 469 postgres mem REG 144,4 0 (deleted)/VE20428-SYSV0052e2c1 (stat: No such file or directory)
postmaste 470 postgres mem REG 144,4 147159237 (deleted)/dev/zero (stat: No such file or directory)
postmaste 470 postgres mem REG 144,4 0 (deleted)/VE20428-SYSV0052e2c1 (stat: No such file or directory)
postmaste 471 postgres mem REG 144,4 147159237 (deleted)/dev/zero (stat: No such file or directory)
postmaste 471 postgres mem REG 144,4 0 (deleted)/VE20428-SYSV0052e2c1 (stat: No such file or directory)
postmaste 472 postgres mem REG 144,4 147159237 (deleted)/dev/zero (stat: No such file or directory)
postmaste 472 postgres mem REG 144,4 0 (deleted)/VE20428-SYSV0052e2c1 (stat: No such file or directory)
httpd 1130 root mem REG 144,4 147485837 (deleted)/dev/zero (stat: No such file or directory)
httpd 1130 root mem REG 144,4 65537 (deleted)/VE20428-SYSV0176748a (stat: No such file or directory)
httpd 1131 apache mem REG 144,4 147485837 (deleted)/dev/zero (stat: No such file or directory)
httpd 1131 apache mem REG 144,4 65537 (deleted)/VE20428-SYSV0176748a (stat: No such file or directory)
httpd 1131 1133 apache mem REG 144,4 147485837 (deleted)/dev/zero (stat: No such file or directory)
httpd 1131 1133 apache mem REG 144,4 65537 (deleted)/VE20428-SYSV0176748a (stat: No such file or directory)
httpd 1131 1134 apache mem REG 144,4 147485837 (deleted)/dev/zero (stat: No such file or directory)
httpd 1131 1134 apache mem REG 144,4 65537 (deleted)/VE20428-SYSV0176748a (stat: No such file or directory)
httpd 1131 1135 apache mem REG 144,4 147485837 (deleted)/dev/zero (stat: No such file or directory)
httpd 1131 1135 apache mem REG 144,4 65537 (deleted)/VE20428-SYSV0176748a (stat: No such file or directory)
httpd 1131 1136 apache mem REG 144,4 147485837 (deleted)/dev/zero (stat: No such file or directory)
httpd 1131 1136 apache mem REG 144,4 65537 (deleted)/VE20428-SYSV0176748a (stat: No such file or directory)
httpd 1131 1137 apache mem REG 144,4 147485837 (deleted)/dev/zero (stat: No such file or directory)
httpd 1131 1137 apache mem REG 144,4 65537 (deleted)/VE20428-SYSV0176748a (stat: No such file or directory)
httpd 1131 1138 apache mem REG 144,4 147485837 (deleted)/dev/zero (stat: No such file or directory)
httpd 1131 1138 apache mem REG 144,4 65537 (deleted)/VE20428-SYSV0176748a (stat: No such file or directory)
httpd 1131 1139 apache mem REG 144,4 147485837 (deleted)/dev/zero (stat: No such file or directory)
httpd 1131 1139 apache mem REG 144,4 65537 (deleted)/VE20428-SYSV0176748a (stat: No such file or directory)
httpd 1131 1140 apache mem REG 144,4 147485837 (deleted)/dev/zero (stat: No such file or directory)
httpd 1131 1140 apache mem REG 144,4 65537 (deleted)/VE20428-SYSV0176748a (stat: No such file or directory)
httpd 1131 1141 apache mem REG 144,4 147485837 (deleted)/dev/zero (stat: No such file or directory)
httpd 1131 1141 apache mem REG 144,4 65537 (deleted)/VE20428-SYSV0176748a (stat: No such file or directory)
httpd 1131 1142 apache mem REG 144,4 147485837 (deleted)/dev/zero (stat: No such file or directory)
httpd 1131 1142 apache mem REG 144,4 65537 (deleted)/VE20428-SYSV0176748a (stat: No such file or directory)
httpd 1131 1143 apache mem REG 144,4 147485837 (deleted)/dev/zero (stat: No such file or directory)
httpd 1131 1143 apache mem REG 144,4 65537 (deleted)/VE20428-SYSV0176748a (stat: No such file or directory)
httpd 1131 1144 apache mem REG 144,4 147485837 (deleted)/dev/zero (stat: No such file or directory)
httpd 1131 1144 apache mem REG 144,4 65537 (deleted)/VE20428-SYSV0176748a (stat: No such file or directory)
httpd 1131 1145 apache mem REG 144,4 147485837 (deleted)/dev/zero (stat: No such file or directory)
httpd 1131 1145 apache mem REG 144,4 65537 (deleted)/VE20428-SYSV0176748a (stat: No such file or directory)
httpd 1131 1146 apache mem REG 144,4 147485837 (deleted)/dev/zero (stat: No such file or directory)
httpd 1131 1146 apache mem REG 144,4 65537 (deleted)/VE20428-SYSV0176748a (stat: No such file or directory)
httpd 1131 1147 apache mem REG 144,4 147485837 (deleted)/dev/zero (stat: No such file or directory)
httpd 1131 1147 apache mem REG 144,4 65537 (deleted)/VE20428-SYSV0176748a (stat: No such file or directory)
httpd 1131 1148 apache mem REG 144,4 147485837 (deleted)/dev/zero (stat: No such file or directory)
httpd 1131 1148 apache mem REG 144,4 65537 (deleted)/VE20428-SYSV0176748a (stat: No such file or directory)
httpd 1131 1149 apache mem REG 144,4 147485837 (deleted)/dev/zero (stat: No such file or directory)
httpd 1131 1149 apache mem REG 144,4 65537 (deleted)/VE20428-SYSV0176748a (stat: No such file or directory)
httpd 1132 apache mem REG 144,4 147485837 (deleted)/dev/zero (stat: No such file or directory)
httpd 1132 apache mem REG 144,4 65537 (deleted)/VE20428-SYSV0176748a (stat: No such file or directory)
httpd 1158 apache mem REG 144,4 147485837 (deleted)/dev/zero (stat: No such file or directory)
httpd 1158 apache mem REG 144,4 65537 (deleted)/VE20428-SYSV0176748a (stat: No such file or directory)
postmaste 1270 postgres mem REG 144,4 147159237 (deleted)/dev/zero (stat: No such file or directory)
postmaste 1270 postgres mem REG 144,4 0 (deleted)/VE20428-SYSV0052e2c1 (stat: No such file or directory)
编辑2：这是第二个命令的输出......
[rails@server ~]$ sudo du -h --max-depth=1 /; ls -plah / | grep -v /
214M /opt
4.0K /media
12K /boot
6.7M /run
4.0K /lost+found
du: cannot access ‘/proc/3478/task/3478/fd/4’: No such file or directory
du: cannot access ‘/proc/3478/task/3478/fdinfo/4’: No such file or directory
du: cannot access ‘/proc/3478/fd/4’: No such file or directory
du: cannot access ‘/proc/3478/fdinfo/4’: No such file or directory
0 /proc
4.0K /dev
4.0K /.cpt_hardlink_dir_a920e4ddc233afddc9fb53d26c392319
114M /tmp
0 /sys
14M /etc
3.6M /root
396M /home
12K /.rbenv
4.0K /srv
1.9G /usr
1.9G /var
8.0K /mnt
4.5G /
total 64K
-rw-r--r-- 1 root root 0 May 5 2018 .autorelabel
-rw-r--r-- 1 root root 0 Nov 8 17:14 reboot
-rw-r--r-- 1 root root 0 Nov 8 17:15 .vzfifo