linux磁盘分区详解
1.磁盘的分区主要分为基本分区（primary partion）和扩充分区(extension partion)两种，基本分区和扩充分区的数目之和不能大于四个。且基本分区可以马上被使用但不能再分区。扩充分区必须再进行分区后才能使用，也就是说它必须还要进行二次分区。那么由扩充分区再分下去的是什么呢？它就是逻辑分区（logical partion），况且逻辑分区没有数量上限制。
在 Linux 中，每一个硬件设备都映射到一个系统的文件，对于硬盘、光驱等 IDE 或 SCSI 设备也不例外。Linux把各种 IDE 设备分配了一个由 hd 前缀组成的文件；而对于各种 SCSI 设备，则分配了一个由 sd 前缀组成的文件。
对于ide硬盘，驱动器标识符为“hdx~”,其中“hd”表明分区所在设备的类型，这里是指ide硬盘了。“x”为盘号（a为基本盘，b为基本从属盘，c为辅助主盘，d为辅助从属盘）,“~”代表分区，前四个分区用数字1到4表示，它们是主分区或扩展分区，从5开始就是逻辑分区。例，hda3表示为第一个ide硬盘上的第三个主分区或扩展分区,hdb2表示为第二个ide硬盘上的第二个主分区或扩展分区。对于scsi硬盘则标识为“sdx~”，scsi硬盘是用“sd”来表示分区所在设备的类型的，其余则和ide硬盘的表示方法一样，不在多说。
在 Linux 中规定，每一个硬盘设备最多能有 4个主分区（其中包含扩展分区）构成，任何一个扩展分区都要占用一个主分区号码，也就是在一个硬盘中，主分区和扩展分区一共最多是 4 个。
Linux 规定了主分区（或者扩展分区）占用 1 至 16 号码中的前 4 个号码。以第一个 IDE 硬盘为例说明，主分区（或者扩展分区）占用了 hda1、hda2、hda3、hda4，而逻辑分区占用了 hda5 到 hda16 等 12 个号码。
因此，Linux 下面每一个硬盘总共最多有 16 个分区。
IDE硬盘最多有64个分区
1.fdisk -l 查看系统分区详细信息
1 [root@test4 ~]# fdisk -l 2 Disk /dev/sda: 21.4 GB, 21474836480 bytes 3 255 heads, 63 sectors/track, 2610 cylinders 4 Units = cylinders of 16065 * 512 = 8225280 bytes 5 6 Device Boot Start End Blocks Id System 7 /dev/sda1 * 1 13 104391 83 Linux 8 /dev/sda2 14 2610 20860402+ 8e Linux LVM
注释：这个硬盘的大小是21.4GB，有255个磁面，63个扇区，2610磁柱(cylinders)
每个cylinder（磁柱）的容量是 8225280 bytes=8225.280 K（约为）=8.225280M（约为）；
Device Boot Start End Blocks Id System
/dev/sda1 * 1 13 104391 83 Linux
/dev/sda2 14 1305 10377990 8e Linux LVM
id和System 表示的是一个意思，id看起来不太直观，我们要在fdisk 一个分区时，通过指定id来确认分区类型；比如 7表示的就NTFS 分区；这个在fdisk 中要通过t功能来指定。83是linux。下面的部分会提到；
说明：硬盘分区的表示：在Linux 是通过hd*x 或 sd*x 表示的：
其中* 表示的是a、b、c ... ...
另外x 表示的数字 1、2、3 ... ...
hd大多是IDE硬盘；sd大多是SCSI或移动存储；引导（Boot）：表示引导分区，在上面的例子中sda1 是引导分区；
Start （开始）：表示的一个分区从Xcylinder（磁柱）开始；
End （结束）：表示一个分区到 Ycylinder（磁柱）结束；
2.fdisk 对磁盘进行分区
[root@test4 ~]# fdisk /dev/sda //对sda磁盘进行分区 Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel Building a new DOS disklabel. Changes will remain in memory only, until you decide to write them. After that, of course, the previous content won't be recoverable. The number of cylinders for this disk is set to 2597. There is nothing wrong with that, but this is larger than 1024, and could in certain setups cause problems with: 1) software that runs at boot time (e.g., old versions of LILO) 2) booting and partitioning software from other OSs (e.g., DOS FDISK, OS/2 FDISK) Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite) Command (m for help): m //输出帮助信息 Command action a toggle a bootable flag //设置启动分区 b edit bsd disklabel //编辑分区标签 c toggle the dos compatibility flag d delete a partition //删除一个分区 l list known partition types //列出分区类型 m print this menu //输出帮助信息 n add a new partition //建立一个新的分区 o create a new empty DOS partition table //创建一个新的空白DOS分区表 p print the partition table //打印分区表 q quit without saving changes //退出不保存设置 s create a new empty Sun disklabel t change a partition's system id //改变分区的ID u change display/entry units //改变显示的单位 v verify the partition table //检查验证分区表 w write table to disk and exit //保存分区表 x extra functionality (experts only) Command (m for help):n Command action e extended //e是扩展分区 p primary partition (1-4) //p是主分区 p Partition number (1-4): 1 //定义分区数量 --主分区最多只能有四个 First cylinder (1-2597, default 1): 1 Last cylinder or +size or +sizeM or +sizeK (1-2597, default 2597): +100M Command (m for help): w //保存刚才的配置信息。 The partition table has been altered! Calling ioctl() to re-read partition table. WARNING: Re-reading the partition table failed with error 22: 无效的参数. The kernel still uses the old table. The new table will be used at the next reboot. Syncing disks.
[root@test6 ~]# fdisk /dev/sda The number of cylinders for this disk is set to 2610. There is nothing wrong with that, but this is larger than 1024, and could in certain setups cause problems with: 1) software that runs at boot time (e.g., old versions of LILO) 2) booting and partitioning software from other OSs (e.g., DOS FDISK, OS/2 FDISK) Command (m for help): n First cylinder (1710-2610, default 1710): Using default value 1710 Last cylinder or +size or +sizeM or +sizeK (1710-2610, default 2610): +100M Command (m for help): w The partition table has been altered! Calling ioctl() to re-read partition table. WARNING: Re-reading the partition table failed with error 16: 设备或资源忙. The kernel still uses the old table. The new table will be used at the next reboot. Syncing disks. [root@test6 ~]# partprobe /dev/sda //对硬盘进行更新 [root@test6 ~]# fdisk -l Disk /dev/sda: 21.4 GB, 21474836480 bytes 255 heads, 63 sectors/track, 2610 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/sda1 * 1 13 104391 83 Linux /dev/sda2 14 274 2096482+ 82 Linux swap / Solaris /dev/sda3 275 404 1044225 8e Linux LVM /dev/sda4 405 2610 17719695 5 Extended /dev/sda5 405 1709 10482381 83 Linux /dev/sda6 1710 1722 104391 83 Linux [root@test6 ~]# mkfs.ext3 /dev/sda6 //需要先进行格式化，才能使用 。mkfs -t ext3 /dev/sda5 （mkfs.ext3 一样效果 -t 指定类型 -b 指定block大小·） mke2fs 1.39 (29-May-2006) Filesystem label= OS type: Linux Block size=1024 (log=0) Fragment size=1024 (log=0) 26104 inodes, 104388 blocks 5219 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 2008 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 23 mounts or 180 days, whichever comes first. Use tune2fs -c or -i to override. [root@test6 ~]# mount /dev/sda6 /mnt/sda7/ //进行挂载使用 anaconda-ks.cfg install.log install.log.syslog [root@test6 ~]# df -h 文件系统 容量 已用 可用 已用% 挂载点 /dev/sda5 9.7G 1.1G 8.1G 12% / /dev/sda1 99M 12M 83M 13% /boot tmpfs 252M 0 252M 0% /dev/shm /dev/hdc 3.9G 3.9G 0 100% /mnt/cdrom /dev/sda6 99M 5.6M 89M 6% /mnt/sda7
1.磁盘管理常用命令
1.1 ls -i 文件名 查看文件存储在哪个innode中
1 [root@test6 ~]# ls -i lstest 2 1179659 lstest
1.2 ls -id 文件夹名 查看文件夹存储在哪个innode中
1 [root@test6 ~]# ls -id lstest1 2 1179661 lstest1
1.3 filefrag -v 文件名 查看文件存储block具体位置
1 [root@test6 ~]# filefrag -v lstest 2 Checking lstest 3 Filesystem type is: ef53 4 Filesystem cylinder groups is approximately 78 5 Blocksize of file lstest is 4096 6 File size of lstest is 5 (1 blocks) 7 First block: 1183744 8 Last block: 1183744 9 lstest: 1 extent found
2.硬盘工具：
2.1 dumpe2fs /dev/sda1 查看分区superblock 和blockgroup等详细信息
[root@test6 ~]# dumpe2fs /dev/sda1 dumpe2fs 1.39 (29-May-2006) Filesystem volume name: /boot Last mounted on: <not available> Filesystem UUID: 0c7f5306-fd13-4b13-819f-4b6cab126938 Filesystem magic number: 0xEF53 Filesystem revision #: 1 (dynamic) Filesystem features: has_journal ext_attr resize_inode dir_index filetype needs_recovery sparse_super Default mount options: user_xattr acl Filesystem state: clean Errors behavior: Continue Filesystem OS type: Linux Inode count: 26104 Block count: 104388 Reserved block count: 5219 Free blocks: 89552 Free inodes: 26069 First block: 1 Block size: 1024 Fragment size: 1024 Reserved GDT blocks: 256 Blocks per group: 8192 Fragments per group: 8192 Inodes per group: 2008 Inode blocks per group: 251 Filesystem created: Tue Mar 28 07:57:05 2017 Last mount time: Tue Mar 28 08:29:57 2017 Last write time: Tue Mar 28 08:29:57 2017 Mount count: 3 Maximum mount count: -1 Last checked: Tue Mar 28 07:57:05 2017 Check interval: 0 (<none>) Reserved blocks uid: 0 (user root) Reserved blocks gid: 0 (group root) First inode: 11 Inode size: 128 Journal inode: 8 //ext3 日志inode位置 Default directory hash: tea Directory Hash Seed: 5e624e4a-049c-4cbf-a65f-8b8a7d08e398 Journal backup: inode blocks Journal size: 4114k //日志文件大小 Group 0: (Blocks 1-8192) Primary superblock at 1, Group descriptors at 2-2 Reserved GDT blocks at 3-258 Block bitmap at 259 (+258), Inode bitmap at 260 (+259) Inode table at 261-511 (+260) 1023 free blocks, 1990 free inodes, 2 directories Free blocks: 4642-5664 Free inodes: 19-2008 Group 1: (Blocks 8193-16384) Backup superblock at 8193, Group descriptors at 8194-8194 Reserved GDT blocks at 8195-8450 Block bitmap at 8451 (+258), Inode bitmap at 8452 (+259) Inode table at 8453-8703 (+260) 4583 free blocks, 2008 free inodes, 0 directories Free blocks: 11802-16384 Free inodes: 2009-4016 Group 2: (Blocks 16385-24576) Block bitmap at 16385 (+0), Inode bitmap at 16386 (+1) Inode table at 16387-16637 (+2) 7939 free blocks, 2008 free inodes, 0 directories Free blocks: 16638-24576 Free inodes: 4017-6024 Group 3: (Blocks 24577-32768) Backup superblock at 24577, Group descriptors at 24578-24578 Reserved GDT blocks at 24579-24834 Block bitmap at 24835 (+258), Inode bitmap at 24836 (+259) Inode table at 24837-25087 (+260) 7439 free blocks, 1991 free inodes, 1 directories Free blocks: 25193-25600, 25609-26112, 26121-26624, 26632-27136, 27144-27648, 27657-28160, 28168-28672, 28683-29184, 29192-29696, 29704-30208, 30218-31744, 31804-32768 Free inodes: 6042-8032 Group 4: (Blocks 32769-40960) Block bitmap at 32769 (+0), Inode bitmap at 32770 (+1) Inode table at 32771-33021 (+2) 7939 free blocks, 2008 free inodes, 0 directories Free blocks: 33022-40960 Free inodes: 8033-10040 Group 5: (Blocks 40961-49152) Backup superblock at 40961, Group descriptors at 40962-40962 Reserved GDT blocks at 40963-41218 Block bitmap at 41219 (+258), Inode bitmap at 41220 (+259) Inode table at 41221-41471 (+260) 7681 free blocks, 2008 free inodes, 0 directories Free blocks: 41472-49152 Free inodes: 10041-12048 Group 6: (Blocks 49153-57344) Block bitmap at 49153 (+0), Inode bitmap at 49154 (+1) Inode table at 49155-49405 (+2) 7939 free blocks, 2008 free inodes, 0 directories Free blocks: 49406-57344 Free inodes: 12049-14056 Group 7: (Blocks 57345-65536) Backup superblock at 57345, Group descriptors at 57346-57346 Reserved GDT blocks at 57347-57602 Block bitmap at 57603 (+258), Inode bitmap at 57604 (+259) Inode table at 57605-57855 (+260) 7681 free blocks, 2008 free inodes, 0 directories Free blocks: 57856-65536 Free inodes: 14057-16064 Group 8: (Blocks 65537-73728) Block bitmap at 65537 (+0), Inode bitmap at 65538 (+1) Inode table at 65539-65789 (+2) 7939 free blocks, 2008 free inodes, 0 directories Free blocks: 65790-73728 Free inodes: 16065-18072 Group 9: (Blocks 73729-81920) Backup superblock at 73729, Group descriptors at 73730-73730 Reserved GDT blocks at 73731-73986 Block bitmap at 73987 (+258), Inode bitmap at 73988 (+259) Inode table at 73989-74239 (+260) 7681 free blocks, 2008 free inodes, 0 directories Free blocks: 74240-81920 Free inodes: 18073-20080 Group 10: (Blocks 81921-90112) Block bitmap at 81921 (+0), Inode bitmap at 81922 (+1) Inode table at 81923-82173 (+2) 7939 free blocks, 2008 free inodes, 0 directories Free blocks: 82174-90112 Free inodes: 20081-22088 Group 11: (Blocks 90113-98304) Block bitmap at 90113 (+0), Inode bitmap at 90114 (+1) Inode table at 90115-90365 (+2) 7939 free blocks, 2008 free inodes, 0 directories Free blocks: 90366-98304 Free inodes: 22089-24096 Group 12: (Blocks 98305-104387) Block bitmap at 98305 (+0), Inode bitmap at 98306 (+1) Inode table at 98307-98557 (+2) 5830 free blocks, 2008 free inodes, 0 directories Free blocks: 98558-104387 Free inodes: 24097-26104
2.2 fsck /dev/sda 检查硬盘情况 -C 显示检查过程 -f 强制检查
2.3 badblocks /dev/sda5 检查硬盘坏道 -sv 显示进度和结果
df 查看文件系统（-h 以合适的单位示系统大小 -T 显示系统类型）
du 查看文件夹大小，包含文件夹里面文件
du -s 仅仅查看文件夹大小
du -h 以M方式显示大小，方便查看
fuser -mv /mnt 当显示 设备正在忙的时候，可以使用这个命令查看使用进程
tune2fs -l /dev/sda 查看磁盘参数（-h 查看可选选项，进行选项更改）
1 [root@test6 ~]# tune2fs -l /dev/sda5 2 tune2fs 1.39 (29-May-2006) 3 Filesystem volume name: / //卷标 4 Last mounted on: <not available> 5 Filesystem UUID: 4b64bcce-0acc-40f2-85e6-07e198152c20 6 Filesystem magic number: 0xEF53 7 Filesystem revision #: 1 (dynamic) 8 Filesystem features: has_journal ext_attr resize_inode dir_index filetype needs_recovery sparse_super large_file 9 Default mount options: user_xattr acl 10 Filesystem state: clean 11 Errors behavior: Continue 12 Filesystem OS type: Linux 13 Inode count: 2621440 14 Block count: 2620595 15 Reserved block count: 131029 16 Free blocks: 2257390 17 Free inodes: 2582833 18 First block: 0 19 Block size: 4096 20 Fragment size: 4096 21 Reserved GDT blocks: 639 22 Blocks per group: 32768 23 Fragments per group: 32768 24 Inodes per group: 32768 25 Inode blocks per group: 1024 26 Filesystem created: Tue Mar 28 07:57:02 2017 27 Last mount time: Tue Mar 28 08:29:56 2017 28 Last write time: Tue Mar 28 08:29:56 2017 29 Mount count: 3 30 Maximum mount count: -1 //超过最大次数，则需要对分区进行自检 31 Last checked: Tue Mar 28 07:57:02 2017 32 Check interval: 0 (<none>) 33 Reserved blocks uid: 0 (user root) 34 Reserved blocks gid: 0 (group root) 35 First inode: 11 36 Inode size: 128 37 Journal inode: 8 38 First orphan inode: 163883 39 Default directory hash: tea 40 Directory Hash Seed: 8633f5c3-e870-428e-8ce3-7d636f0ef80a 41 Journal backup: inode blocks
e21able /dev/sda7 aa 卷标的另一种改法
