服务器磁盘满无法释放空间解析及解决
硬盘显示被写满，但是用du -sh /*查看时占用硬盘空间之和还远小于硬盘大小
使用df -h查看，磁盘空间确实是满的，即找不到硬盘分区是怎么被写满的。
了解前因后果后，得知，这台WEB服务器的日志文件被删除了，目的是想清除日志文件占用的大量磁盘空间，但是当文件在一直被 写入的这个过程中，我们是无法彻底的删除的。
因此产生了这样的一个问题，下面我来模拟一下：
[root@oldboyedu test]# dd if=/dev/zero of=/dev/sdc bs=10M count=10 10+0 records in 10+0 records out 104857600 bytes (105 MB) copied, 2.18347 s, 48.0 MB/s [root@oldboyedu test]# ll -hi /dev/sdc 48657 -rw-r--r--. 1 root root 100M Jul 14 19:08 /dev/sdc [root@oldboyedu test]# mkfs -t ext4 /dev/sdc mke2fs 1.41.12 (17-May-2010) /dev/sdc is not a block special device. Proceed anyway? (y,n) y Filesystem label= OS type: Linux Block size=1024 (log=0) Fragment size=1024 (log=0) Stride=0 blocks, Stripe width=0 blocks 25688 inodes, 102400 blocks 5120 blocks (5.00%) reserved for the super user First data block=1 Maximum filesystem blocks=67371008 13 block groups 8192 blocks per group, 8192 fragments per group 1976 inodes per group Superblock backups stored on blocks: 8193, 24577, 40961, 57345, 73729 Writing inode tables: done Creating journal (4096 blocks): done Writing superblocks and filesystem accounting information: done This filesystem will be automatically checked every 22 mounts or 180 days, whichever comes first. Use tune2fs -c or -i to override. [root@oldboyedu test]# tune2fs -c -1 /dev/sdc tune2fs 1.41.12 (17-May-2010) Setting maximal mount count to -1 [root@oldboyedu test]# mkdir /log [root@oldboyedu test]# mount -o loop /dev/sdc /log [root@oldboyedu log]# dd if=/dev/zero of=/log/1.txt bs=10M count=8 8+0 records in 8+0 records out 83886080 bytes (84 MB) copied, 0.287821 s, 291 MB/s [root@oldboyedu log]# echo "dddd">>1.txt [root@oldboyedu log]# df -h Filesystem Size Used Avail Use% Mounted on /dev/sda3 19G 1.5G 17G 8% / tmpfs 491M 0 491M 0% /dev/shm /dev/sda1 190M 35M 146M 19% /boot /dev/sdc 93M 82M 6.4M 93% /log
我重新打开一个终端执行以下命令：
[root@oldboyedu ~]# tail -f /log/1.txt dddd
然后准备删除，查看结果
[root@oldboyedu log]# rm 1.txt -f [root@oldboyedu log]# df -h Filesystem Size Used Avail Use% Mounted on /dev/sda3 19G 1.5G 17G 8% / tmpfs 491M 0 491M 0% /dev/shm /dev/sda1 190M 35M 146M 19% /boot /dev/sdc 93M 82M 6.4M 93% /log [root@oldboyedu log]# ll total 12 drwx------. 2 root root 12288 Jul 14 19:11 lost+found [root@oldboyedu log]# du -sh /log 13K /log [root@oldboyedu log]# du -sh /log/* 12K /log/lost+found [root@oldboyedu log]# df -h Filesystem Size Used Avail Use% Mounted on /dev/sda3 19G 1.5G 17G 8% / tmpfs 491M 0 491M 0% /dev/shm /dev/sda1 190M 35M 146M 19% /boot /dev/sdc 93M 82M 6.4M 93% /log [root@oldboyedu log]# lsof |grep deleted tail 3029 root 3r REG 7,0 83886085 12 /log/1.txt (deleted) [root@oldboyedu log]# kill -15 3029 [root@oldboyedu log]# df -h Filesystem Size Used Avail Use% Mounted on /dev/sda3 19G 1.5G 17G 8% / tmpfs 491M 0 491M 0% /dev/shm /dev/sda1 190M 35M 146M 19% /boot /dev/sdc 93M 1.6M 87M 2% /log [root@oldboyedu log]# lsof |grep deleted [root@oldboyedu log]#
