Ａ、磁盘配额作用限制普通用户使用磁盘空间，不至于因为个别人的浪费而影响到其它人的正常使用；
Ｂ、需要内核的支持；
Ｃ、只有Ext2/Ext3文件系统目前支持这种功能；
Ｄ、需要用户程序quota软件包.
磁盘配额配置过程
１）、使用usrquota，grpquota选项挂载一个分区，激活内核的支持（只能在分区上做）
２）、方法：#mount –o usrquota,grpquota /dev/sdb1 /mnt/d1
或 mount –o remount,usrquota,grpquota / (因为根目录已经挂载过，可重新挂载)
３）、init 1 （进入单用户环境来配置）
４）、quotacheck –cvuga 检查并创建磁盘配额的数据库文件（存放位置：在每一个分区的根目录下面）
-c： 创建create； –v：更详细地表述；–u：用户user；–g：组group；-a：所有all
５）、edquota –u
６）、quota命令可以查看用户的配额使用情况
如：[root@localhost root]# ls /mnt
cdrom floppy
[root@localhost root]# mkfs.ext3 /dev/sdb1 /mnt/sd1/
mke2fs 1.32 (09-Nov-2002)
mkfs.ext3: bad blocks count - /mnt/sd1/
[root@localhost root]# mkfs.ext3 -f /dev/sdb1 /mnt/sd1/
[root@localhost root]# fdisk -l
Disk /dev/sda: 5368 MB, 5368709120 bytes
255 heads, 63 sectors/track, 652 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sda1 * 1 652 5237158+ 83 Linux
Disk /dev/sdb: 4294 MB, 4294967296 bytes
255 heads, 63 sectors/track, 522 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sdb1 250 522 2192872+ 83 Linux
[root@localhost root]# mkfs.ext3 /dev/sdb1
mke2fs 1.32 (09-Nov-2002)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
274176 inodes, 548218 blocks
27410 blocks (5.00%) reserved for the super user
First data block=0
17 block groups
32768 blocks per group, 32768 fragments per group
16128 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912
Writing inode tables: done
Creating journal (8192 blocks): done
Writing superblocks and filesystem accounting information: done
This filesystem will be automatically checked every 30 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
[root@localhost root]# mount /dev/sdb1 /mnt/sd1 -o usrquota,grpquota
[root@localhost root]# mount
/dev/sda1 on / type ext3 (rw)
none on /proc type proc (rw)
usbdevfs on /proc/bus/usb type usbdevfs (rw)
none on /dev/pts type devpts (rw,gid=5,mode=620)
none on /dev/shm type tmpfs (rw)
/dev/sdb1 on /mnt/sd1 type ext3 (rw,usrquota,grpquota)
[root@localhost root]# more /etc/mtab
/dev/sda1 / ext3 rw 0 0
none /proc proc rw 0 0
usbdevfs /proc/bus/usb usbdevfs rw 0 0
none /dev/pts devpts rw,gid=5,mode=620 0 0
none /dev/shm tmpfs rw 0 0
/dev/sdb1 /mnt/sd1 ext3 rw,usrquota,grpquota 0 0
[root@localhost root]# quotacheck –cvuga <-------
quotacheck: Scanning /dev/sdb1 [/mnt/sd1] done
quotacheck: Checked 2 directories and 0 files
[root@localhost root]# ls /mnt/sd1/
aquota.group aquota.user lost+found
aquota.group 和aquota.user两个数据文件，用来分配组和用户的配额情况。
[root@localhost root]# quotaon 或reboot或quotaon /dev/sdb1
[root@localhost root]# edquota -u redhat
Disk quotas for user redhat (uid 502):
Filesystem blocks soft hard inodes soft hard
/dev/sdb1 125 10 0 80 0 10
注：blocks表示：块的数量；inodes表示：节点的数量或建立文件的个数；
soft表示：软限制，可以超过这个数值的设定，但是有天数限制；
hard表示：硬限制，这是一个任何时候也不能超过的数值，永远不可能达到。
[root@localhost root]# ls /mnt/sd1
aquota.group aquota.user lost+found
[root@localhost root]# mkdir /mnt/sd1/redhat
[root@localhost root]# chown redhat /mnt/sd1/redhat/
[root@localhost root]# su - redhat
[redhat@localhost redhat]$ pwd
/home/redhat
[redhat@localhost redhat]$ cd /mnt/sd1/redhat/
[redhat@localhost redhat]$ pwd
/mnt/sd1/redhat
[redhat@localhost redhat]$ quota
Disk quotas for user redhat (uid 502):
Filesystem blocks quota limit grace files quota limit grace
/dev/sdb1 4 10 0 1 0&n
