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詳解Linux系統(tǒng)磁盤
Linux 磁盤管理好壞直接關(guān)系到整個(gè)系統(tǒng)的性能問(wèn)題，本篇文章重點(diǎn)為大家講解一下Linux系統(tǒng)磁盤。
1、 磁盤分類
目前市場(chǎng)上的磁盤分類有：IDE磁盤（多用于PC機(jī)）、SATA磁盤、SAS磁盤、SSD磁盤等這么幾種分類，企業(yè)中服務(wù)器大多為后面的兩種，SATA磁盤多用于企業(yè)內(nèi)部的一些業(yè)務(wù)、SAS磁盤多用于對(duì)外的業(yè)務(wù)（一些業(yè)務(wù)平臺(tái)）。
SATA磁盤目前容量最大為4T、SAS磁盤一般都在300G–600G居多，企業(yè)生產(chǎn)環(huán)境中使用也最多的是這種容量的，實(shí)際生產(chǎn)中磁盤的使用主要是看性能需求，也就是磁盤的讀寫速度。
2、 磁盤的體系結(jié)構(gòu)
企業(yè)級(jí)服務(wù)器多塊磁盤的情況
Linux系統(tǒng)磁盤詳解Linux系統(tǒng)磁盤詳解
3、 磁盤容量的計(jì)算
磁盤的結(jié)構(gòu)一般包括磁道、盤面、扇區(qū)、碰頭等
一個(gè)磁道的大小=512 字節(jié)*扇區(qū)數(shù)
一個(gè)盤面的大小=磁道的大小*磁道數(shù)
一個(gè)磁盤的大小=盤面大小*磁頭數(shù)
因此，一個(gè)磁盤的容量=512 字節(jié)扇區(qū)數(shù)磁道數(shù)*磁頭數(shù)
Linux系統(tǒng)磁盤詳解Linux系統(tǒng)磁盤詳解
4、 磁盤分區(qū)
所有磁盤的分區(qū)信息都是存儲(chǔ)在分區(qū)表中，Linux系統(tǒng)僅支持4個(gè)分區(qū)表信息（主分區(qū)+擴(kuò)展分區(qū)），一個(gè)分區(qū)表的大小在64bytes
Linux一般分為三個(gè)分區(qū)分別是：boot分區(qū)、swap分區(qū)、/根分區(qū)
Linux的分區(qū)編號(hào)：主分區(qū)1-4，邏輯分區(qū)從5開(kāi)始計(jì)算
實(shí)際生產(chǎn)環(huán)境分區(qū)要求
1、 最少要有/和swap兩個(gè)分區(qū)
2、 swap（虛擬內(nèi)存）=1.5*物理內(nèi)存大小，一般大小于或等于16G的物理內(nèi)存的服務(wù)器，swap分區(qū)一般都直接設(shè)置為16G大小
3、 建議設(shè)置/boot分區(qū)，Linux引導(dǎo)分區(qū)，如內(nèi)核文件等，一般所有文件一共才幾十M的大小，因此這個(gè)分區(qū)就設(shè)置為100-200M即可
5、 磁盤分區(qū)工具fdisk
fdisk是針對(duì)磁盤容量小于2T
[root@cairui ~]# fdisk --help
fdisk: invalid option -- '-'
fdisk: Usage:
fdisk [options] change partition table
fdisk [options] -l list partition table(s)
fdisk -s give partition size(s) in blocks
Options:
-b sector size (512, 1024, 2048 or 4096)
-c switch off DOS-compatible mode
-h print help
-u give sizes in sectors instead of cylinders
-v print version
-C specify the number of cylinders
-H specify the number of heads
-S specify the number of sectors per track
: Success
Linux系統(tǒng)磁盤詳解Linux系統(tǒng)磁盤詳解
[root@localhost ~]# fdisk /dev/sda1 #對(duì)/dev/sda1進(jìn)行分區(qū)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(gè)分區(qū)
l list known partition types
m print this menu
n add a new partition #新建一個(gè)分區(qū)
o create a new empty DOS partition table
p print the partition table #打印出分區(qū)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(qū)信息寫入分區(qū)表并退出程序 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(shè)置起始柱面 Using default value 1 Last cylinder, +cylinders or +size{K,M,G} (1-2610, default 2610): 設(shè)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 打印分區(qū)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(qū)完成后執(zhí)行 partprobe 通知系統(tǒng)分區(qū)表發(fā)生改變
接下來(lái)進(jìn)行格式化分區(qū)
[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(qū)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、 磁盤分區(qū)工具parted
由于環(huán)境限制無(wú)法有2T或者以上大小的磁盤，只能模擬環(huán)境來(lái)使用parted分區(qū)工具來(lái)進(jìn)行分區(qū)
[root@Centos ~]# parted /dev/sdb mklabel gpt
將磁盤轉(zhuǎn)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 打印分區(qū)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(qū)并設(shè)置大小
Information: You may need to update /etc/fstab.
[root@Centos ~]# parted /dev/sdb p 打印分區(qū)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
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