Linux 文件删除后未释放空间解决办法

现象

文件删除后，磁盘空间未释放。

排查

使用lsof命令查看哪些文件已经被删除，而系统扔持有该文件的句柄未释放（其他进程中正在使用该文件）。

lsof | grep deleted

输出

java       89018 root  125w  REG               0,22                      /logs/log-info.log (deleted)

查看进程为89018的125号文件描述符，还保留着原始文件的内容，清空之。

> /proc/89018/fd/125

备注

对于deleted文件句柄的释放，目前已知的解决方案是重启应用。

lsof字段含义

使用man lsof查看更多字段。

FD         is the File Descriptor number of the file or:

               cwd  current working directory;
               Lnn  library references (AIX);
               err  FD information error (see NAME column);
               jld  jail directory (FreeBSD);
               ltx  shared library text (code and data);
               Mxx  hex memory-mapped type number xx.
               m86  DOS Merge mapped file;
               mem  memory-mapped file;
               mmap memory-mapped device;
               pd   parent directory;
               rtd  root directory;
               tr   kernel trace file (OpenBSD);
               txt  program text (code and data);
               v86  VP/ix mapped file;

          FD is followed by one of these characters, describing the mode under which the file is open:

               r for read access;
               w for write access;
               u for read and write access;
               space if mode unknown and no lock
                    character follows;
               ‘-’ if mode unknown and lock
                    character follows.

          The mode character is followed by one of these lock characters, describing the type of lock applied to the file:

               N for a Solaris NFS lock of unknown type;
               r for read lock on part of the file;
               R for a read lock on the entire file;
               w for a write lock on part of the file;
               W for a write lock on the entire file;
               u for a read and write lock of any length;
               U for a lock of unknown type;
               x for an SCO OpenServer Xenix lock on part      of the file;
               X for an SCO OpenServer Xenix lock on the      entire file;
               space if there is no lock.

          See the LOCKS section for more information on the lock information character.

          The FD column contents constitutes a single field for parsing in post-processing scripts.