Linux磁盘分区
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1、添加10G的硬盘。 实际上在服务器上支持热插拔
2、fdisk -l查看
[root@linux-xl ~]# fdisk -l #如果识别不到新插的硬盘，查看磁盘，虚拟机正常需要重启才能加载新的磁盘。
Disk /dev/sda: 53.7 GB, 53687091200 bytes, 104857600 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x000cd7c5
Device Boot Start End Blocks Id System
/dev/sda1 * 2048 2099199 1048576 83 Linux
/dev/sda2 2099200 94373887 46137344 83 Linux
/dev/sda3 94373888 102502399 4064256 82 Linux swap / Solaris
/dev/sda4 102502400 104857599 1177600 5 Extended
/dev/sda5 102504448 104601599 1048576 83 Linux
Disk /dev/sdb: 10.7 GB, 10737418240 bytes, 20971520 sectors #这里的sdb为新加的磁盘
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
3、对于磁盘可以不分区，直接格式化一整块使用；但通常都是先分区，后格式化。
fdisk是mbr分区模式，最高只支持2TB，最多只有主分区primary加上扩展分区extended为4，想要多个分区需要第四个分区为扩展分区extended，并在扩展分区里面分多个逻辑分区。 扩展分区仅仅只是一个外壳不支持格式化，真正存储的是逻辑分区。
[root@linux-xl ~]# fdisk /dev/sdb
Welcome to fdisk (util-linux 2.23.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Device does not contain a recognized partition table
Building a new DOS disklabel with disk identifier 0x189fc246.
Command (m for help): n #创建一个新的分区(这里通常使用的是 n：创建一个新的分区；p：罗列出分区；w：保存并退出；d：删除一个分区；q：不保存直接退出)
Partition type:
p primary (0 primary, 0 extended, 4 free) #主分区：如果想都用分区，最多只能划分四个
e extended #扩展分区：包含逻辑分区
Select (default p): p
Partition number (1-4, default 1): 1
First sector (2048-20971519, default 2048): #这里起始扇区都使用默认，直接回车即可。
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-20971519, default 20971519):+2G #划分2个G的空间。
Partition 1 of type Linux and of size 2 GiB is set
Command (m for help): p #列出分区
Disk /dev/sdb: 10.7 GB, 10737418240 bytes, 20971520 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x189fc246
Device Boot Start End Blocks Id System
/dev/sdb1 2048 4196351 2097152 83 Linux # 此时可以看到刚划分的分区
Command (m for help): n #主分区分完过后，再新建分区就不会提示了
Partition type:
p primary (1 primary, 0 extended, 3 free)
e extended
Select (default p): #默认回车
Using default response p
Partition number (2-4, default 2): #默认回车
First sector (4196352-20971519, default 4196352): #默认回车
Using default value 4196352
Last sector, +sectors or +size{K,M,G} (4196352-20971519, default 20971519): +2G #新建2G的主分区
Partition 2 of type Linux and of size 2 GiB is set
Command (m for help): p #列出分区
Disk /dev/sdb: 10.7 GB, 10737418240 bytes, 20971520 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x189fc246
Device Boot Start End Blocks Id System
/dev/sdb1 2048 4196351 2097152 83 Linux
/dev/sdb2 4196352 8390655 2097152 83 Linux
Command (m for help): n #新建一个分区
Partition type:
p primary (2 primary, 0 extended, 2 free)
e extended
Select (default p): #回车默认主分区
Using default response p
Partition number (3,4, default 3): #默认回车从3开始
First sector (8390656-20971519, default 8390656): #默认回车
Using default value 8390656
Last sector, +sectors or +size{K,M,G} (8390656-20971519, default 20971519): +1G #划分1个G的主分区
Partition 3 of type Linux and of size 1 GiB is set
Command (m for help): p #列出分区
Disk /dev/sdb: 10.7 GB, 10737418240 bytes, 20971520 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x189fc246
Device Boot Start End Blocks Id System
/dev/sdb1 2048 4196351 2097152 83 Linux
/dev/sdb2 4196352 8390655 2097152 83 Linux
/dev/sdb3 8390656 10487807 1048576 83 Linux
Command (m for help): n #新建分区
Partition type:
p primary (3 primary, 0 extended, 1 free)
e extended
Select (default e): e #划分扩展分区
Selected partition 4
First sector (10487808-20971519, default 10487808): #默认回车
Using default value 10487808
Last sector, +sectors or +size{K,M,G} (10487808-20971519, default 20971519): #默认回车划分剩余空间给扩展分区
Using default value 20971519
Partition 4 of type Extended and of size 5 GiB is set
Command (m for help): p #列出分区
Disk /dev/sdb: 10.7 GB, 10737418240 bytes, 20971520 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x189fc246
Device Boot Start End Blocks Id System
/dev/sdb1 2048 4196351 2097152 83 Linux
/dev/sdb2 4196352 8390655 2097152 83 Linux
/dev/sdb3 8390656 10487807 1048576 83 Linux
/dev/sdb4 10487808 20971519 5241856 5 Extended
Command (m for help): n #可以看到提示变了，只能是划分逻辑分区了。
All primary partitions are in use
Adding logical partition 5
First sector (10489856-20971519, default 10489856):
Using default value 10489856
Last sector, +sectors or +size{K,M,G} (10489856-20971519, default 20971519): +1G #划分1G大小的逻辑分区
Partition 5 of type Linux and of size 1 GiB is set
Command (m for help): p #列出分区
Disk /dev/sdb: 10.7 GB, 10737418240 bytes, 20971520 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x189fc246
Device Boot Start End Blocks Id System
/dev/sdb1 2048 4196351 2097152 83 Linux
/dev/sdb2 4196352 8390655 2097152 83 Linux
/dev/sdb3 8390656 10487807 1048576 83 Linux
/dev/sdb4 10487808 20971519 5241856 5 Extended
/dev/sdb5 10489856 12587007 1048576 83 Linux
Command (m for help): n #再划分一个逻辑分区
All primary partitions are in use
Adding logical partition 6
First sector (12589056-20971519, default 12589056):
Using default value 12589056
Last sector, +sectors or +size{K,M,G} (12589056-20971519, default 20971519): +1G #划分1G大小的逻辑分区
Partition 6 of type Linux and of size 1 GiB is set
Command (m for help): p #列出分区
Disk /dev/sdb: 10.7 GB, 10737418240 bytes, 20971520 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x189fc246
Device Boot Start End Blocks Id System
/dev/sdb1 2048 4196351 2097152 83 Linux
/dev/sdb2 4196352 8390655 2097152 83 Linux
/dev/sdb3 8390656 10487807 1048576 83 Linux
/dev/sdb4 10487808 20971519 5241856 5 Extended
/dev/sdb5 10489856 12587007 1048576 83 Linux
/dev/sdb6 12589056 14686207 1048576 83 Linux
Command (m for help): d #删掉一个分区6
Partition number (1-6, default 6): 6 #回车默认是6
Partition 6 is deleted
Command (m for help): p #列出分区
Disk /dev/sdb: 10.7 GB, 10737418240 bytes, 20971520 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x189fc246
Device Boot Start End Blocks Id System
/dev/sdb1 2048 4196351 2097152 83 Linux
/dev/sdb2 4196352 8390655 2097152 83 Linux
/dev/sdb3 8390656 10487807 1048576 83 Linux
/dev/sdb4 10487808 20971519 5241856 5 Extended
/dev/sdb5 10489856 12587007 1048576 83 Linux
Command (m for help): w #保存并退出
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
查看刚划分出来的分区，此时已经成功划分。下一步就是格式化了。
[root@linux-xl ~]# fdisk -l /dev/sdb
Disk /dev/sdb: 10.7 GB, 10737418240 bytes, 20971520 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x189fc246
Device Boot Start End Blocks Id System
/dev/sdb1 2048 4196351 2097152 83 Linux
/dev/sdb2 4196352 8390655 2097152 83 Linux
/dev/sdb3 8390656 10487807 1048576 83 Linux
/dev/sdb4 10487808 20971519 5241856 5 Extended
/dev/sdb5 10489856 12587007 1048576 83 Linux
当我们在创建磁盘分区的时候，有三种分区可选，扩展分区（e），主分区（p），逻辑分区（l）。
我们最多只能创建4个分区（4个中不包括逻辑分区），如果想创建多个分区，可以是3个主分区和1个扩展分区组合。然后在扩展分区中，创建逻辑分区（可以创建无限个逻辑分区）； 需要注意的是，扩展分区相当于一个空壳子，是不可以格式化的（不可以使用），只有它的子分区才可以格式化。在fdisk中划分分区的时候，使用d选项可以删除你想要删除的那个分区，需要注意的是，当扩展分区中有子分区（逻辑分区）的时候，删除扩展分区会连同子分区一起删除。
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