EXT3 文件系统
block size=1024时，单个文件最大支持16GB
block size=4096时，单个文件最大支持4TB （官方说是2TB）
计算方式：
表 1. 各种数据块对应的文件寻址范围
| 块大小 | 直接寻址 | 间接寻址 | 二次间接寻址 | 三次间接寻址 |
| 1024 | 12KB | 268KB | 64.26MB | 16.06GB |
| 2048 | 24KB | 1.02MB | 513.02MB | 265.5GB |
| 4096 | 48KB | 4.04MB | 4GB | ~ 4TB |
详细资料查看：
http://zh.wikipedia.org/zh-cn/Ext3
如何查看某分区文件系统信息：
[root@fedora13 ~]# df -lh
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vg_fedora13-LogVol00
92G 4.7G 82G 6% /
tmpfs 1007M 1.9M 1005M 1% /dev/shm
/dev/sda1 485M 60M 400M 14% /boot
/dev/mapper/vg_fedora13-LogVol01
202G 43G 149G 23% /home
/home/wuhaoshu/os/Fedora-13-i386-DVD.iso
3.1G 3.1G 0 100% /mnt/cdrom
[root@fedora13 ~]# tune2fs -l /dev/mapper/vg_fedora13-LogVol01
tune2fs 1.41.10 (10-Feb-2009)
Filesystem volume name: <none>
Last mounted on: <not available>
Filesystem UUID: 435579c0-0af8-44fb-8ffe-2b67790729ba
Filesystem magic number: 0xEF53
Filesystem revision #: 1 (dynamic)
Filesystem features: has_journal ext_attr resize_inode dir_index filetype needs_recovery sparse_super large_file
Filesystem flags: signed_directory_hash
Default mount options: user_xattr acl
Filesystem state: clean
Errors behavior: Continue
Filesystem OS type: Linux
Inode count: 13443072
Block count: 53755904
Reserved block count: 2687795
Free blocks: 42509664
Free inodes: 13426199
First block: 0
Block size: 4096
Fragment size: 4096
Reserved GDT blocks: 1011
Blocks per group: 32768
Fragments per group: 32768
Inodes per group: 8192
Inode blocks per group: 512
Filesystem created: Mon Aug 9 12:54:11 2010
Last mount time: Wed Aug 25 09:54:31 2010
Last write time: Wed Aug 25 09:54:31 2010
Mount count: 28
Maximum mount count: -1
Last checked: Mon Aug 9 12:54:11 2010
Check interval: 0 (<none>)
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: 9ee3f59d-ad94-48ab-a183-1f4eaac37285
Journal backup: inode blocks
[root@fedora13 ~]#
