파일 시스템이 "/etc/fstab"에 표시되지만 "df -a"를 사용하지 않습니까?

/etc/fstab다음 파일 시스템이 표시 되지만 사용되지 않는 이유를 이해할 수 없습니다 df -a.

/dev/sdb1 /var/log/apache_logs          reiserfs    user,noauto,rw,exec,suid,user_xattr        0       2

/var/log/apache_logs폴더가 존재하고 액세스할 수 있음 을 확인했습니다 .

df -a이 명령은 모든 파일 시스템을 나열 하면 안 되나요 ?

$ df -a
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/mapper/ghost-root
                       7583436   1252188   5946020  18% /
proc                         0         0         0   -  /proc
none                         0         0         0   -  /sys
none                         0         0         0   -  /sys/fs/fuse/connections
none                         0         0         0   -  /sys/kernel/debug
none                         0         0         0   -  /sys/kernel/security
udev                    254652       164    254488   1% /dev
none                         0         0         0   -  /dev/pts
none                    254652         0    254652   0% /dev/shm
none                    254652        52    254600   1% /var/run
none                    254652         0    254652   0% /var/lock
none                    254652         0    254652   0% /lib/init/rw
/dev/sdc1               198321      5763    182319   4% /tmp
/dev/sda5               233335     12670    208217   6% /boot
$ cat /etc/fstab
# /etc/fstab: static file system information.
#
# Use 'blkid -o value -s UUID' to print the universally unique identifier
# for a device; this may be used with UUID= as a more robust way to name
# devices that works even if disks are added and removed. See fstab(5).
#
# <file system> <mount point>   <type>  <options>       <dump>  <pass>
proc            /proc           proc    defaults        0       0
/dev/mapper/ghost-root /               ext4    errors=remount-ro 0       1
# /boot was on /dev/sda5 during installation
UUID=f9f46813-a78a-42e8-a007-53308212ee26 /boot           ext2    defaults        0       2
/dev/sdb1 /var/log/apache_logs          reiserfs    user,noauto,rw,exec,suid,user_xattr        0       2
/dev/sdc1 /tmp         ext2        noexec,nosuid,rw                    0       0
/dev/mapper/ghost-swap_1 none            swap    sw              0       0
/dev/scd0       /media/cdrom0   udf,iso9660 user,noauto,exec,utf8 0       0
/dev/fd0        /media/floppy0  auto    rw,user,noauto,exec,utf8 0       0
$