早上好，我的备份机器有一个“小”问题。它无法进行备份，因为它检测到已使用 96% 的空间。但事实并非如此。
我在物理机上启动了一些命令，这里我给你输出。
ubuntu@BACKUP:~$ sudo df -h
Filesystem Size Used Avail Use% Mounted on
udev 992M 0 992M 0% /dev
tmpfs 200M 21M 180M 11% /run
/dev/xvda1 20G 4.8G 15G 25% /
tmpfs 1000M 0 1000M 0% /dev/shm
tmpfs 5.0M 0 5.0M 0% /run/lock
tmpfs 1000M 0 1000M 0% /sys/fs/cgroup
/dev/mapper/vg_data-lv_data_backup 640G 580G 30G 96% /data/backup
/dev/mapper/vg_data-lv_data_archive 640G 49G 559G 9% /mnt/lv_data_archive
tmpfs 200M 0 200M 0% /run/user/1000
正如你所看到的，在/dev/mapper/vg_data-lv_data_backup有30GB消失了。我知道这是一个外部4分区并为 root 命令保留 5% 的空间。但这并不能证明这个错误的空间是合理的......
这里是其他命令：
root@BACKUP:/data# du -h -d1 /data/backup
16K /data/backup/lost+found
531G /data/backup/BackupPC
50G /data/backup/DumpDB
580G /data/backup
ubuntu@BACKUP:~$ sudo lsof +L1 | numfmt --field=7 --to=iec --invalid='ignore'
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NLINK NODE NAME
systemd-j 388 root txt REG 202,1 319K 0 52456 /lib/systemd/systemd-journald (deleted)
dhclient 1010 root txt REG 202,1 476K 0 4269 /sbin/dhclient (deleted)
lxcfs 1202 root txt REG 202,1 19K 0 24454 /usr/bin/lxcfs (deleted)
systemd-l 1233 root txt REG 202,1 605K 0 52482 /lib/systemd/systemd-logind (deleted)
agetty 1476 root txt REG 202,1 44K 0 4308 /sbin/agetty (deleted)
agetty 1482 root txt REG 202,1 44K 0 4308 /sbin/agetty (deleted)
BackupPC 1625 backuppc txt REG 202,1 1.9M 0 6550 /usr/bin/perl (deleted)
root@BACKUP:/data# dumpe2fs -h /dev/mapper/vg_data-lv_data_backup
dumpe2fs 1.42.13 (17-May-2015)
Filesystem volume name: <none>
Last mounted on: /data/backup
Filesystem UUID: 8f2689b8-6ed0-47d2-833c-904097eb6a34
Filesystem magic number: 0xEF53
Filesystem revision #: 1 (dynamic)
Filesystem features: has_journal ext_attr resize_inode dir_index filetype needs_recovery extent flex_bg sparse_super large_file huge_file uninit_bg dir_nlink extra_isize
Filesystem flags: signed_directory_hash
Default mount options: user_xattr acl
Filesystem state: clean
Errors behavior: Continue
Filesystem OS type: Linux
Inode count: 42598400
Block count: 170393600
Reserved block count: 7869498
Free blocks: 57647530
Free inodes: 40094191
First block: 0
Block size: 4096
Fragment size: 4096
Reserved GDT blocks: 983
Blocks per group: 32768
Fragments per group: 32768
Inodes per group: 8192
Inode blocks per group: 512
Flex block group size: 16
Filesystem created: Tue Aug 22 12:04:28 2017
Last mount time: Fri Dec 15 12:20:05 2017
Last write time: Fri Dec 15 12:20:05 2017
Mount count: 16
Maximum mount count: -1
Last checked: Tue Aug 22 12:04:28 2017
Check interval: 0 (<none>)
Lifetime writes: 5450 GB
Reserved blocks uid: 0 (user root)
Reserved blocks gid: 0 (group root)
First inode: 11
Inode size: 256
Required extra isize: 28
Desired extra isize: 28
Journal inode: 8
Default directory hash: half_md4
Directory Hash Seed: fd48ebc6-99be-468a-8c2d-3aa600ce2412
Journal backup: inode blocks
Journal features: journal_incompat_revoke
Journal size: 128M
Journal length: 32768
Journal sequence: 0x00011b23
Journal start: 30397
谢谢
答案1
正如您所写，ext4 为 root 保留了 5% 的空间。不是针对根“命令”，而是针对文件。 640 Gb 的 5% 是 32 Gb，其模数舍入误差就是您要查找的磁盘空间量。这些 Gb 物理上位于磁盘上，但普通用户无法使用，因此未显示在 的“可用”列中df。