Linux系統磁碟

所有有系統都一樣，都是一種軟體被安裝於某個硬體之上，這個硬體無外非是一種存儲設備，通常操作系統都是安裝在磁碟中，所以Linux系統也是一樣，都是安裝在磁碟中，但是它與Windows系統不一樣，因為Linux都是需要創建文件系統才可以使用。

1、  磁碟分類

　　目前市場上的磁碟分類有：IDE磁碟（多用於PC機）、SATA磁碟、SAS磁碟、SSD磁碟等這麼幾種分類，企業中伺服器大多為後面的兩種，SATA磁碟多用於企業內部的一些業務、SAS磁碟多用於對外的業務（一些業務平臺）。

　　SATA磁碟目前容量最大為4T、SAS磁碟一般都在300G--600G居多，企業生產環境中使用也最多的是這種容量的，實際生產中磁碟的使用主要是看性能需求，也就是磁碟的讀寫速度。

2、  磁碟的體繫結構

企業級伺服器多塊磁碟的情況

3、  磁碟容量的計算

磁碟的結構一般包括磁軌、盤面、扇區、碰頭等

一個磁軌的大小=512 位元組*扇區數
一個盤面的大小=磁軌的大小*磁軌數
一個磁碟的大小=盤面大小*磁頭數
因此
一個磁碟的容量=512 位元組*扇區數*磁軌數*磁頭數

4、  磁碟分區

所有磁碟的分區信息都是存儲在分區表中，Linux系統僅支持4個分區表信息（主分區+擴展分區），一個分區表的大小在64bytes

Linux一般分為三個分區分別是：boot分區、swap分區、/根分區

Linux的分區編號：主分區1-4，邏輯分區從5開始計算

實際生產環境分區要求

　　1、  最少要有/和swap兩個分區

　　2、  swap（虛擬記憶體）=1.5*物理記憶體大小，一般大小於或等於16G的物理記憶體的伺服器，swap分區一般都直接設置為16G大小

　　3、  建議設置/boot分區，Linux引導分區，如內核文件等，一般所有文件一共才幾十M的大小，因此這個分區就設置為100-200M即可

5、  磁碟分區工具fdisk

fdisk是針對磁碟容量小於2T

[root@cairui ~]# fdisk --help
fdisk: invalid option -- '-'

fdisk: Usage:
 fdisk [options] <disk>    change partition table
 fdisk [options] -l <disk> list partition table(s)
 fdisk -s <partition>      give partition size(s) in blocks

Options:
 -b <size>                 sector size (512, 1024, 2048 or 4096)
 -c                        switch off DOS-compatible mode
 -h                        print help
 -u <size>                 give sizes in sectors instead of cylinders
 -v                        print version
 -C <number>               specify the number of cylinders
 -H <number>               specify the number of heads
 -S <number>               specify the number of sectors per track

: Success

[root@localhost ~]# fdisk /dev/sda1　　#對/dev/sda1進行分區操作
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel with disk identifier 0x02fadd9c.
Changes will remain in memory only, until you decide to write them.
After that, of course, the previous content won't be recoverable.

Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)

WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
         switch off the mode (command 'c') and change display units to
         sectors (command 'u').

Command (m for help): m
Command action
   a   toggle a bootable flag
   b   edit bsd disklabel
   c   toggle the dos compatibility flag
   d   delete a partition　　#刪除一個分區
   l   list known partition types
   m   print this menu
   n   add a new partition　　#新建一個分區
   o   create a new empty DOS partition table
   p   print the partition table　　#列印出分區表信息
   q   quit without saving changes　　#不保存退出
   s   create a new empty Sun disklabel
   t   change a partition's system id
   u   change display/entry units
   v   verify the partition table
   w   write table to disk and exit　　#將分區信息寫入分區表並退出程式
   x   extra functionality (experts only)

Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-2610, default 1): 設置起始柱面
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-2610, default 2610):
設置大小或柱面
Using default value 2610
Command (m for help): m
Command action
a toggle a bootable flag
b edit bsd disklabel
c toggle the dos compatibility flag
d delete a partition
l list known partition types
m print this menu
n add a new partition
o create a new empty DOS partition table
p print the partition table
q quit without saving changes
s create a new empty Sun disklabel
t change a partition's system id
u change display/entry units
v verify the partition table
w write table to disk and exit
x extra functionality (experts only)
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
Command (m for help): p 列印分區表信息
Disk /dev/sdb: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
121 / 753
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xb712cc55
Device Boot Start End Blocks Id System
/dev/sdb1 1 2610 20964793+ 83 Linux
分區完成後執行 partprobe 通知系統分區表發生改變
接下來進行格式化分區
[root@Centos ~]# mkfs.ext3 /dev/sdb1
mke2fs 1.41.12 (17-May-2010)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
1310720 inodes, 5241198 blocks
262059 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=4294967296
160 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
4096000
Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done
This filesystem will be automatically checked every 24 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
[root@Centos ~]# tune2fs -c -1 /dev/sdb1
tune2fs 1.41.12 (17-May-2010)
Setting maximal mount count to -1
[root@Centos ~]# mount /dev/sdb1 /mnt 掛載分區至/mnt 下
[root@Centos ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup-lv_root 50G 3.5G 44G 8% /
tmpfs 932M 0 932M 0% /dev/shm
/dev/sda1 485M 39M 421M 9% /boot
122 / 753
/dev/mapper/VolGroup-lv_home 26G 215M 24G 1% /home
/dev/sdb1 20G 172M 19G 1% /mnt

6、  磁碟分區工具parted

由於環境限制無法有2T或者以上大小的磁碟，只能模擬環境來使用parted分區工具來進行分區

[root@Centos ~]# parted /dev/sdb mklabel gpt
將磁碟轉換成 gpt 的格式
[root@Centos ~]# parted /dev/sdb mkpart primary 0 200（200M）
Warning: The resulting partition is not properly aligned for best
performance.
Ignore/Cancel? Ignore
[root@Centos ~]# parted /dev/sdb p 列印分區表信息
Model: VMware, VMware Virtual S (scsi)
Disk /dev/sdb: 1074MB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Number Start End Size File system Name Flags
1 17.4kB 200MB 200MB primary
[root@Centos ~]# parted /dev/sdb mkpart primary 201 1073
分區並設置大小
Information: You may need to update /etc/fstab.
[root@Centos ~]# parted /dev/sdb p 列印分區表信息
Model: VMware, VMware Virtual S (scsi)
Disk /dev/sdb: 1074MB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Number Start End Size File system Name Flags
1 17.4kB 200MB 200MB primary
2 201MB 1073MB 871MB primary
[root@Centos ~]# mkfs.ext4 /dev/sdb1
mke2fs 1.41.12 (17-May-2010)
Filesystem label=
OS type: Linux
Block size=1024 (log=0)
Fragment size=1024 (log=0)
123 / 753
Stride=0 blocks, Stripe width=0 blocks
48960 inodes, 195296 blocks
9764 blocks (5.00%) reserved for the super user
First data block=1
Maximum filesystem blocks=67371008
24 block groups
8192 blocks per group, 8192 fragments per group
2040 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 36 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
[root@Centos ~]# tune2fs -c -1 /dev/sdb1
tune2fs 1.41.12 (17-May-2010)
Setting maximal mount count to -1
[root@Centos ~]# mount /dev/sdb1 /mnt
[root@Centos ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup-lv_root 50G 3.5G 44G 8% /
tmpfs 932M 0 932M 0% /dev/shm
/dev/sda1 485M 39M 421M 9% /boot
/dev/mapper/VolGroup-lv_home 26G 215M 24G 1% /home
/dev/sdb1 185M 5.6M 170M 4% /mnt

[root@cairui ~]# parted --help
Usage: parted [OPTION]... [DEVICE [COMMAND [PARAMETERS]...]...]
Apply COMMANDs with PARAMETERS to DEVICE.  If no COMMAND(s) are given, run in
interactive mode.

OPTIONs:
  -h, --help                      displays this help message
  -l, --list                      lists partition layout on all block devices
  -m, --machine                   displays machine parseable output
  -s, --script                    never prompts for user intervention
  -v, --version                   displays the version
  -a, --align=[none|cyl|min|opt]  alignment for new partitions

COMMANDs:
  align-check TYPE N                        check partition N for TYPE(min|opt)
        alignment
  check NUMBER                             do a simple check on the file system
  cp [FROM-DEVICE] FROM-NUMBER TO-NUMBER   copy file system to another partition
  help [COMMAND]                           print general help, or help on
        COMMAND
  mklabel,mktable LABEL-TYPE               create a new disklabel (partition
        table)
  mkfs NUMBER FS-TYPE                      make a FS-TYPE file system on
        partition NUMBER
  mkpart PART-TYPE [FS-TYPE] START END     make a partition
  mkpartfs PART-TYPE FS-TYPE START END     make a partition with a file system
  move NUMBER START END                    move partition NUMBER
  name NUMBER NAME                         name partition NUMBER as NAME
  print [devices|free|list,all|NUMBER]     display the partition table,
        available devices, free space, all found partitions, or a particular
        partition
  quit                                     exit program
  rescue START END                         rescue a lost partition near START
        and END
  resize NUMBER START END                  resize partition NUMBER and its file
        system
  rm NUMBER                                delete partition NUMBER
  select DEVICE                            choose the device to edit
  set NUMBER FLAG STATE                    change the FLAG on partition NUMBER
  toggle [NUMBER [FLAG]]                   toggle the state of FLAG on partition
        NUMBER
  unit UNIT                                set the default unit to UNIT
  version                                  display the version number and
        copyright information of GNU Parted