2016-08-26：
授课内容：
1、SWAP交换分区的创建
2、dd命令的使用
3、设定文件系统配额
4、设定和管理软RAID设备
5、配置逻辑卷、逻辑卷快照
1、swap
(1)SWAP分区：模拟内存，当物理内存不足时，进程需要内存资源是，内存会把一部分没有在用的进程分页挪到硬盘的模拟内存中，腾出空间被现在需要使用内存资源的进程
即其作用是可以允许内存过载使用，windows系统也有类似的机制，由于虚拟内存空间是建立在硬盘之上，所以其速度和性能会大打折扣，所以适合临时使用
(2)创建SWAP分区：
相关命令：mkswap、swapon
示例：
[19:42 root@Centos6.8/usr/local/http2]# fdisk /dev/sda 【创建分区】
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): n
First cylinder (9460-26109, default 9460):
Using default value 9460
Last cylinder, +cylinders or +size{K,M,G} (9460-26109, default 26109): +2G
Command (m for help): t
Partition number (1-6): 6
Hex code (type L to list codes): L
0 Empty 24 NEC DOS 81 Minix / old Lin bf Solaris
1 FAT12 39 Plan 9 82 Linux swap / So c1 DRDOS/sec (FAT-
2 XENIX root 3c PartitionMagic 83 Linux c4 DRDOS/sec (FAT-
3 XENIX usr 40 Venix 80286 84 OS/2 hidden C: c6 DRDOS/sec (FAT-
4 FAT16 <32M 41 PPC PReP Boot 85 Linux extended c7 Syrinx
5 Extended 42 SFS 86 NTFS volume set da Non-FS data
6 FAT16 4d QNX4.x 87 NTFS volume set db CP/M / CTOS / .
7 HPFS/NTFS 4e QNX4.x 2nd part 88 Linux plaintext de Dell Utility
8 AIX 4f QNX4.x 3rd part 8e Linux LVM df BootIt
9 AIX bootable 50 OnTrack DM 93 Amoeba e1 DOS access
a OS/2 Boot Manag 51 OnTrack DM6 Aux 94 Amoeba BBT e3 DOS R/O
b W95 FAT32 52 CP/M 9f BSD/OS e4 SpeedStor
c W95 FAT32 (LBA) 53 OnTrack DM6 Aux a0 IBM Thinkpad hi eb BeOS fs
e W95 FAT16 (LBA) 54 OnTrackDM6 a5 FreeBSD ee GPT
f W95 Ext'd (LBA) 55 EZ-Drive a6 OpenBSD ef EFI (FAT-12/16/
10 OPUS 56 Golden Bow a7 NeXTSTEP f0 Linux/PA-RISC b
11 Hidden FAT12 5c Priam Edisk a8 Darwin UFS f1 SpeedStor
12 Compaq diagnost 61 SpeedStor a9 NetBSD f4 SpeedStor
14 Hidden FAT16 <3 63 GNU HURD or Sys ab Darwin boot f2 DOS secondary
16 Hidden FAT16 64 Novell Netware af HFS / HFS+ fb VMware VMFS
17 Hidden HPFS/NTF 65 Novell Netware b7 BSDI fs fc VMware VMKCORE
18 AST SmartSleep 70 DiskSecure Mult b8 BSDI swap fd Linux raid auto
1b Hidden W95 FAT3 75 PC/IX bb Boot Wizard hid fe LANstep
1c Hidden W95 FAT3 80 Old Minix be Solaris boot ff BBT
1e Hidden W95 FAT1
Hex code (type L to list codes): 82 【选择swap模式】
Changed system type of partition 6 to 82 (Linux swap / Solaris)
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: Device or resource busy.
The kernel still uses the old table. The new table will be used at
the next reboot or after you run partprobe(8) or kpartx(8)
Syncing disks.
[19:43 root@Centos6.8/usr/local/http2]# mkswap /dev/sda6 【格式化交换分区】
Setting up swapspace version 1, size = 2100024 KiB
no label, UUID=ae9d3eee-1908-47fe-9b32-2a777d0b28b1
[19:43 root@Centos6.8/usr/local/http2]# swapon -a 【挂载swap】
[19:44 root@Centos6.8/usr/local/http2]# free 【查看已经挂载成功】
total used free shared buffers cached
Mem: 1907300 1059764 847536 1336 65000 724408
-/+ buffers/cache: 270356 1636944
Swap: 4095996 0 4095996
[19:44 root@Centos6.8/usr/local/http2]# cat /proc/swaps
FilenameTypeSizeUsedPriority
/dev/sda5 partition40959960-1
2、dd命令的使用；
dd：convert and copy a file，转换并复制文件，与cp命令相似，只是用法格式有不一样，dd复制的是数据流，工作在vfs之下
用法：
dd if=/PATH/FROM/SRC of=/PATH/TO/DEST bs=#：block size, 复制单元大小 count=#：复制多少个bs
of=file写到所命名的文件而不是到标准输出
if=file从所命名文件读取而不是从标准输入
bs=size指定块大小（既是是ibs也是obs)
ibs=size一次读size个byte
obs=size 一次写size个byte
cbs=size 一次转化size个byte
skip=blocks从开头忽略blocks个ibs大小的块
seek=blocks从开头忽略blocks个obs大小的块
count=n只拷贝n个记录
cbs=size 一次转换多少byte
说明：
磁盘拷贝：
dd if=/dev/sda of=/dev/sdb
备份MBR：
dd if=/dev/sda of=/tmp/mbr.bak bs=512 count=1
破坏MBR中的bootloader：
dd if=/dev/zero of=/dev/sda bs=64 count=1 seek=446
有一个大与2K的二进制文件fileA。现在想从第64个字节位置开始读取，需要读取的大小是128Byts。又有fileB, 想把上面读取到的128Bytes写到第32个字节开始的位置，替换128Bytes，请问如何实现？
dd if=fileA of=fileB bs=1 count=128 skip=63 seek=31 conv=notrunc
备份：
dd if=/dev/sdx of=/dev/sdy
将本地的/dev/sdx整盘备份到/dev/sdy
dd if=/dev/sdx of=/path/to/image
将/dev/sdx全盘数据备份到指定路径的image文件
dd if=/dev/sdx | gzip >/path/to/image.gz
备份/dev/sdx全盘数据，并利用gzip工具进行压缩，保存到指定路径
恢复：
dd if=/path/to/image of=/dev/sdx
将备份文件恢复到指定盘
gzip -dc /path/to/image.gz | dd of=/dev/sdx
将压缩的备份文件恢复到指定盘
3、文件系统配额：以文件系统（分区）为单位启用
分区配额管理：在一个分区内进行管理
(1)、启用磁盘配额：
分区挂载选项（在fstab修改挂载属性:usrquota,grpquota）：
usrquota：控制单个用户
grpquota：控制组用户
(2)、创建配额数据库
quotacheck -cug /filesystem 成功后会在文件系统有两个aquota的文件
[root@localhost home]# ll total 36 -rw-------. 1 root root 7168 Aug 26 15:04 aquota.group -rw-------. 1 root root 7168 Aug 26 15:04 aquota.user drwxr-xr-x. 4 hill root 4096 Aug 26 15:00 hill drwx------. 2 root root 16384 Aug 26 14:50 lost+found [root@localhost home]# getenforce Enforcing [root@localhost home]# setenforce 0 [root@localhost home]# getenforce Permissive
(3)、启用
quotaon /filesystem
(4)、设置用户配额：
edqupta USERNAME
根据文件所有者来定义用户使用了多大
(5)、查看、测试
[root@localhost home]# repquota -a *** Report for user quotas on device /dev/sda6 Block grace time: 7days; Inode grace time: 7days Block limits File limits User used soft hard grace used soft hard grace ---------------------------------------------------------------------- root -- 141468 0 0 4 0 0 hill -- 36 50000 60000 9 0 0
4、RAID：（raid的最小存储单位是chunk，即每次平均分到物理磁盘的大小）
(1)RAID：Redundant Array of Inexpensive Disks：廉价磁盘冗余阵列
：Redundant Array of Independent Disks：独立磁盘冗余阵列
【注意】：由于在用户层面看来，raid组成一块磁盘，所以要对磁盘进行分区、格式化才能使用
(2)RAID级别：仅代表磁盘组织方式不同，没有上下之分；
0： 条带
性能提升: 读，写
冗余能力（容错能力）: 无
空间利用率：nS
至少2块盘
1： 镜像
性能表现：写性能下降，读性能提升
冗余能力：有
空间利用率：1/2
至少2块盘
2
3
4:
5: 带基偶校验位
性能表现：读，写提升
冗余能力：有
空间利用率：(n-1)/n
至少需要3块
10:
性能表现：读、写提升
冗余能力：有
空间利用率：1/2
至少需要4块
01:
性能表现：读、写提升
冗余能力：有
空间利用率：1/2
至少需要4块
50:
性能表现：读、写提升
冗余能力：有
空间利用率：(n-2)/n
至少需要6块
jbod:
性能表现：无提升
冗余能力：无
空间利用率：100%
至少需要2块
(3)实现RAID方式：
硬RAID（实际生产环节）：
外接专门的存储机箱，机箱里接上多个硬盘
BIOS中进行设置
软RAID（系统演示环节，并不建议在生产环节使用）：mdadm
RAID设备(软raid)可命名为/dev/md0、/dev/md1、/dev/md2、/dev/md3等等
(4)软件raid
命令的语法格式：mdadm[mode] <raiddevice> [options] <component-devices>
模式：
创建：-C
装配: -A
监控: -F
管理：-f, -r, -a
<raiddevice>: /dev/md#
<component-devices>: 任意块设备
-C: 创建模式
-n #: 使用#个块设备来创建此RAID
-l #：指明要创建的RAID的级别
-a {yes|no}：自动创建目标RAID设备的设备文件
-c CHUNK_SIZE: 指明块大小
-x #: 指明空闲盘的个数
-D：显示raid的详细信息；
mdadm -D /dev/md#
管理模式：
-f: 标记指定磁盘为损坏
-a: 添加磁盘
-r: 移除磁盘
观察md的状态：
cat /proc/mdstat
使用mdadm创建并定义RAID设备
#mdadm -C /dev/md0 -a yes -l 5 -n 3 -x 1 /dev/sdb1 /dev/sdc1 /dev/sdd1 /dev/sde1
用文件系统对每个RAID设备进行格式化
#mke2fs -j /dev/md0
测试RAID设备
使用mdadm检查RAID设备的状况
#mdadm –detail|D /dev/md0
增加新的成员
#mdadm –G /dev/md0 –n4 -a /dev/sdf1
模拟磁盘故障
#mdadm /dev/md0 -f /dev/sda1
移除磁盘
#mdadm /dev/md0 –r /dev/sda1
从软件RAID磁盘修复磁盘故障
替换出故障的磁盘然后开机
在备用驱动器上重建分区
#mdadm /dev/md0 -a /dev/sda1
5、逻辑卷管理器（LVM）【最小的存储单位PE(Physical Extend)】
(1)允许在多个物理设备间重新组织文件系统
LVM可以弹性的更改LVM的容量:通过交换PE来进行资料的转换，将原来LV内的PE转移到其他的设备中以降低LV的容量，或将其他设备中的PE加到LV中以加大容量
一个VG最多只能有35565个PE，一个PE默认是4M,所以一个VG默认最大是35565*4=256G，要想调整VG的默认大小，就要调整PE的大小。
(2)LVM管理分为三层来管理：
LV（logical volume）
VG（volume group）
PV（physical volume）
创建LV逻辑卷的过程：要先把物理磁盘创建为物理卷PV，再由多个物理卷创建为卷组VG(相当于扩展分区的概念，不能直接使用)，再在VG卷组上创建需要的逻辑卷LV
(3)相关命令（相似）：
PV：pvcreate、pvremove、pvmove、pvextend、pvdisplay
VG：vgcreate、vgreduce、vgextend、vgdisplay
LV：lvcreate、lvremove、lvextend、lvdisplay
pv管理工具
显示pv信息
pvs：简要pv信息显示
pvdisplay
创建pv
pvcreate /dev/DEVICE
vg管理工具
显示卷组
vgs
vgdisplay
创建卷组
vgcreate [-s #[kKmMgGtTpPeE]] VolumeGroupName PhysicalDevicePath [PhysicalDevicePath…]
管理卷组
vgextend VolumeGroupName PhysicalDevicePath [PhysicalDevicePath…]
vgreduce VolumeGroupName PhysicalDevicePath [PhysicalDevicePath…]
删除卷组
先做pvmove，再做vgremove
lv管理工具
显示逻辑卷
lvs
Lvdisplay
创建逻辑卷
lvcreate-L #[mMgGtT] -n NAME VolumeGroup
删除逻辑卷
lvremove/dev/VG_NAME/LV_NAME
重设文件系统大小
fsadm[options] resize device [new_size[BKMGTEP]]
resize2fs [-f] [-F] [-M] [-P] [-p] device [new_size]
实例：创建LV过程：
简述： 一、分区
fdisk /dev/sda t 8e
partx -a /dev/sda
lsblk
2、
pvcreate /dev/sd{a7,b}
pvs
pvdisplay
3、
vgcreate vg0 /dev/sd{a7,b}
vgs;pvs;pvdisplay;vgdisplay
4、lvcreate -n lv0 -L 10G vg0
5、mkfs.ext4 /dev/vg0/lv0
6、
vi /etc/fstab
mkdir /mnt/lv0;mount -a
二、扩展逻辑卷lv（可以在没有卸载的情况下进行扩展）
1、lvdisplay
2、lvextend -L +1G /dev/vg0/lv0 #先物理扩展
3、resize2fs /dev/vg0/lv0 #后逻辑扩展
4、lvdisplay
三、扩展卷组VG
1、vgdisplay
2、pvcreat /dev/sdb
3、vgextend vg0 /dev/sdb
四、缩减逻辑卷
注意：1、不能在线缩减，得先卸载；
2、确保缩减后的空间大小依然能存储原有的所有数据；
3、在缩减之前应该先强行检查文件，以确保文件系统处于一至性状态；
df -lh
umount
e2fsck -f
resize2fs /PATH/TO/PV 3G #先逻辑缩减
lvreduce -L [-]# /PATH/TO/LV #后物理缩减
mount
1、创建LV
[16:18 root@Centos6.8~]# fdisk /dev/sda
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): t
Partition number (1-8): 8
Hex code (type L to list codes): L
0 Empty 24 NEC DOS 81 Minix / old Lin bf Solaris
1 FAT12 39 Plan 9 82 Linux swap / So c1 DRDOS/sec (FAT-
2 XENIX root 3c PartitionMagic 83 Linux c4 DRDOS/sec (FAT-
3 XENIX usr 40 Venix 80286 84 OS/2 hidden C: c6 DRDOS/sec (FAT-
4 FAT16 <32M 41 PPC PReP Boot 85 Linux extended c7 Syrinx
5 Extended 42 SFS 86 NTFS volume set da Non-FS data
6 FAT16 4d QNX4.x 87 NTFS volume set db CP/M / CTOS / .
7 HPFS/NTFS 4e QNX4.x 2nd part 88 Linux plaintext de Dell Utility
8 AIX 4f QNX4.x 3rd part 8e Linux LVM df BootIt
9 AIX bootable 50 OnTrack DM 93 Amoeba e1 DOS access
a OS/2 Boot Manag 51 OnTrack DM6 Aux 94 Amoeba BBT e3 DOS R/O
b W95 FAT32 52 CP/M 9f BSD/OS e4 SpeedStor
c W95 FAT32 (LBA) 53 OnTrack DM6 Aux a0 IBM Thinkpad hi eb BeOS fs
e W95 FAT16 (LBA) 54 OnTrackDM6 a5 FreeBSD ee GPT
f W95 Ext'd (LBA) 55 EZ-Drive a6 OpenBSD ef EFI (FAT-12/16/
10 OPUS 56 Golden Bow a7 NeXTSTEP f0 Linux/PA-RISC b
11 Hidden FAT12 5c Priam Edisk a8 Darwin UFS f1 SpeedStor
12 Compaq diagnost 61 SpeedStor a9 NetBSD f4 SpeedStor
14 Hidden FAT16 <3 63 GNU HURD or Sys ab Darwin boot f2 DOS secondary
16 Hidden FAT16 64 Novell Netware af HFS / HFS+ fb VMware VMFS
17 Hidden HPFS/NTF 65 Novell Netware b7 BSDI fs fc VMware VMKCORE
18 AST SmartSleep 70 DiskSecure Mult b8 BSDI swap fd Linux raid auto
1b Hidden W95 FAT3 75 PC/IX bb Boot Wizard hid fe LANstep
1c Hidden W95 FAT3 80 Old Minix be Solaris boot ff BBT
1e Hidden W95 FAT1
Hex code (type L to list codes): 8e
Changed system type of partition 8 to 8e (Linux LVM)
Command (m for help): t
Partition number (1-8): 7
Hex code (type L to list codes): 8e
Changed system type of partition 7 to 8e (Linux LVM)
Command (m for help): t
Partition number (1-8): 6
Hex code (type L to list codes): 8e
Changed system type of partition 6 to 8e (Linux LVM)
Command (m for help): p
Disk /dev/sda: 214.7 GB, 214748364800 bytes
255 heads, 63 sectors/track, 26108 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000e82d5
Device Boot Start End Blocks Id System
/dev/sda1 * 1 26 204800 83 Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2 26 6400 51200000 83 Linux
/dev/sda3 6400 8950 20480000 83 Linux
/dev/sda4 8950 26109 137829376 5 Extended
/dev/sda5 8950 9460 4096000 82 Linux swap / Solaris
/dev/sda6 9460 9721 2100029 8e Linux LVM
/dev/sda7 9722 9983 2104483+ 8e Linux LVM
/dev/sda8 9984 10376 3156741 8e Linux LVM
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: Device or resource busy.
The kernel still uses the old table. The new table will be used at
the next reboot or after you run partprobe(8) or kpartx(8)
Syncing disks.
[16:18 root@Centos6.8~]# partx -a /dev/sda
BLKPG: Device or resource busy
error adding partition 1
BLKPG: Device or resource busy
error adding partition 2
BLKPG: Device or resource busy
error adding partition 3
BLKPG: Device or resource busy
error adding partition 4
BLKPG: Device or resource busy
error adding partition 5
BLKPG: Device or resource busy
error adding partition 6
BLKPG: Device or resource busy
error adding partition 7
BLKPG: Device or resource busy
error adding partition 8
[16:19 root@Centos6.8~]# pvdisplay
[16:19 root@Centos6.8~]# pvcreate /dev/sda{6,7,8}
Physical volume "/dev/sda6" successfully created
Physical volume "/dev/sda7" successfully created
Physical volume "/dev/sda8" successfully created
[16:20 root@Centos6.8~]# pvdisplay
"/dev/sda6" is a new physical volume of "2.00 GiB"
--- NEW Physical volume ---
PV Name /dev/sda6
VG Name
PV Size 2.00 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID OcC0N8-Ojcf-6oPq-gvaS-Dny2-JVs4-Lds51R
"/dev/sda7" is a new physical volume of "2.01 GiB"
--- NEW Physical volume ---
PV Name /dev/sda7
VG Name
PV Size 2.01 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID amnydg-48Qm-tIZs-ZXnp-ngWA-4Fuk-6k53TP
"/dev/sda8" is a new physical volume of "3.01 GiB"
--- NEW Physical volume ---
PV Name /dev/sda8
VG Name
PV Size 3.01 GiB
Allocatable NO
PE Size 0
Total PE 0
Free PE 0
Allocated PE 0
PV UUID mir8t7-yoTX-1pAD-A6bA-Gl4U-JYLe-pSmPSc
[16:20 root@Centos6.8~]# vgdisplay
[16:20 root@Centos6.8~]# vgcreate vg0 /dev/sda{6,7,8}
Volume group "vg0" successfully created
[16:20 root@Centos6.8~]# vgdisplay
--- Volume group ---
VG Name vg0
System ID
Format lvm2
Metadata Areas 3
Metadata Sequence No 1
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 0
Open LV 0
Max PV 0
Cur PV 3
Act PV 3
VG Size 7.01 GiB
PE Size 4.00 MiB
Total PE 1795
Alloc PE / Size 0 / 0
Free PE / Size 1795 / 7.01 GiB
VG UUID OXd09k-uQ7C-BMNr-gkeY-HeQv-NJnP-H9WWxQ
[16:20 root@Centos6.8~]# lvdisplay
[16:21 root@Centos6.8~]# lvcreate -n lv0 -L 5G vg0
Logical volume "lv0" created.
[16:21 root@Centos6.8~]# lvdisplay
--- Logical volume ---
LV Path /dev/vg0/lv0
LV Name lv0
VG Name vg0
LV UUID 32AMUw-xgxw-ejJ2-rps1-fm0e-feYw-OoTPS8
LV Write Access read/write
LV Creation host, time Centos6.8, 2016-08-27 16:21:48 +0800
LV Status available
# open 0
LV Size 5.00 GiB
Current LE 1280
Segments 2
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:0
[16:22 root@Centos6.8~]# vgdisplay
--- Volume group ---
VG Name vg0
System ID
Format lvm2
Metadata Areas 3
Metadata Sequence No 2
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 1
Open LV 0
Max PV 0
Cur PV 3
Act PV 3
VG Size 7.01 GiB
PE Size 4.00 MiB
Total PE 1795
Alloc PE / Size 1280 / 5.00 GiB
Free PE / Size 515 / 2.01 GiB
VG UUID OXd09k-uQ7C-BMNr-gkeY-HeQv-NJnP-H9WWxQ
[16:25 root@Centos6.8~]# mke2fs -j /dev/vg0/lv0
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
327680 inodes, 1310720 blocks
65536 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=1342177280
40 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
Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done
This filesystem will be automatically checked every 27 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
[16:26 root@Centos6.8~]# mkdir /mnt/lv0
[16:26 root@Centos6.8~]# mount /dev/vg0/lv0 /mnt/lv0/
[16:26 root@Centos6.8~]# mo
modem-manager mogrify mount.cifs mountpoint mozilla-plugin-config
modinfo montage mount.fuse mountstats
modprobe more mount.nfs mount.tmpfs
modutil mount mount.nfs4 mousetweaks
2、 扩展逻辑卷（要在挂载状态执行resize2fs）
[16:28 root@Centos6.8/mnt/lv0]# lvdisplay --- Logical volume --- LV Path /dev/vg0/lv0 LV Name lv0 VG Name vg0 LV UUID 32AMUw-xgxw-ejJ2-rps1-fm0e-feYw-OoTPS8 LV Write Access read/write LV Creation host, time Centos6.8, 2016-08-27 16:21:48 +0800 LV Status available # open 1 LV Size 5.00 GiB Current LE 1280 Segments 2 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 253:0 [16:36 root@Centos6.8/mnt/lv0]# lvextend -L +1G /dev/vg0/lv0 #物理先扩展 Size of logical volume vg0/lv0 changed from 5.00 GiB (1280 extents) to 6.00 GiB (1536 extents). Logical volume lv0 successfully resized. [16:36 root@Centos6.8/mnt/lv0]# lvdisplay --- Logical volume --- LV Path /dev/vg0/lv0 LV Name lv0 VG Name vg0 LV UUID 32AMUw-xgxw-ejJ2-rps1-fm0e-feYw-OoTPS8 LV Write Access read/write LV Creation host, time Centos6.8, 2016-08-27 16:21:48 +0800 LV Status available # open 1 LV Size 6.00 GiB Current LE 1536 Segments 3 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 253:0 [16:36 root@Centos6.8/mnt/lv0]# resize2fs /dev/vg0/lv0 #逻辑再扩展 resize2fs 1.41.12 (17-May-2010) Filesystem at /dev/vg0/lv0 is mounted on /mnt/lv0; on-line resizing required old desc_blocks = 1, new_desc_blocks = 1 Performing an on-line resize of /dev/vg0/lv0 to 1572864 (4k) blocks. The filesystem on /dev/vg0/lv0 is now 1572864 blocks long. [16:37 root@Centos6.8/mnt/lv0]# df Filesystem 1K-blocks Used Available Use% Mounted on /dev/sda2 50264772 4865484 42839288 11% / tmpfs 953648 72 953576 1% /dev/shm /dev/sda1 194241 39020 144981 22% /boot /dev/sda3 20027260 44996 18958264 1% /testdir /dev/mapper/vg0-lv0 6192704 141436 5736708 3% /mnt/lv0
3、扩展卷组
[16:58 root@Centos6.8/mnt/lv0]# pvcreate /dev/sda9 Physical volume "/dev/sda9" successfully created [16:58 root@Centos6.8/mnt/lv0]# vgextend vg0 /dev/sda9 Volume group "vg0" successfully extended [16:58 root@Centos6.8/mnt/lv0]# vgdisplay --- Volume group --- VG Name vg0 System ID Format lvm2 Metadata Areas 4 Metadata Sequence No 4 VG Access read/write VG Status resizable MAX LV 0 Cur LV 1 Open LV 1 Max PV 0 Cur PV 4 Act PV 4 VG Size 9.02 GiB PE Size 4.00 MiB Total PE 2308 Alloc PE / Size 1536 / 6.00 GiB Free PE / Size 772 / 3.02 GiB VG UUID OXd09k-uQ7C-BMNr-gkeY-HeQv-NJnP-H9WWxQ
4、缩减逻辑卷
没有做文件系统检测和resize2fs，直接缩减，会使原来逻辑卷的数据损坏：
[17:28 root@Centos6.8~]# ll /mnt/lv0/ total 20 -rw-rw-r--. 1 hill hill 0 Aug 27 17:23 f1 drwx------. 2 root root 16384 Aug 27 16:26 lost+found drwxr-xr-x. 2 hill hill 4096 Aug 27 17:24 pam.d [19:00 root@Centos6.8~]# umount /mnt/lv0/ [19:00 root@Centos6.8~]# lvreduce -L 3G /dev/vg0/lv0 WARNING: Reducing active logical volume to 3.00 GiB. THIS MAY DESTROY YOUR DATA (filesystem etc.) Do you really want to reduce vg0/lv0? [y/n]: y Size of logical volume vg0/lv0 changed from 7.00 GiB (1792 extents) to 3.00 GiB (768 extents). Logical volume lv0 successfully resized. [19:05 root@Centos6.8~]# cd /mnt/lv0/ [19:05 root@Centos6.8/mnt/lv0]# ll ls: cannot access pam.d: Input/output error total 16 -rw-rw-r--. 1 hill hill 0 Aug 27 17:23 f1 drwx------. 2 root root 16384 Aug 27 16:26 lost+found d?????????? ? ? ? ? ? pam.d [19:05 root@Centos6.8/mnt/lv0]# cd pam.d -bash: cd: pam.d: Input/output error [19:05 root@Centos6.8/mnt/lv0]#
正确步骤：
[19:20 root@Centos6.8~]# umount /mnt/lv0/ #先卸载 [19:21 root@Centos6.8~]# e2fsck -f /dev/vg0/lv0 #对文件系统进行强制检测 e2fsck 1.41.12 (17-May-2010) Pass 1: Checking inodes, blocks, and sizes Pass 2: Checking directory structure Pass 3: Checking directory connectivity Pass 4: Checking reference counts Pass 5: Checking group summary information /dev/vg0/lv0: 12/327680 files (0.0% non-contiguous), 38512/1310720 blocks [19:21 root@Centos6.8~]# resize2fs /dev/vg0/lv0 3G #逻辑先调整文件系统大小 resize2fs 1.41.12 (17-May-2010) Resizing the filesystem on /dev/vg0/lv0 to 786432 (4k) blocks. The filesystem on /dev/vg0/lv0 is now 786432 blocks long. [19:22 root@Centos6.8~]# lvdisplay #查看缩减前的LV大小 --- Logical volume --- LV Path /dev/vg0/lv0 LV Name lv0 VG Name vg0 LV UUID 32AMUw-xgxw-ejJ2-rps1-fm0e-feYw-OoTPS8 LV Write Access read/write LV Creation host, time Centos6.8, 2016-08-27 16:21:48 +0800 LV Status available # open 0 LV Size 5.00 GiB Current LE 1280 Segments 2 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 253:0 [19:22 root@Centos6.8~]# lvreduce -L 3G /dev/vg0/lv0 #物理缩减LV大小 WARNING: Reducing active logical volume to 3.00 GiB. THIS MAY DESTROY YOUR DATA (filesystem etc.) Do you really want to reduce vg0/lv0? [y/n]: y Size of logical volume vg0/lv0 changed from 5.00 GiB (1280 extents) to 3.00 GiB (768 extents). Logical volume lv0 successfully resized. [19:22 root@Centos6.8~]# lvdisplay --- Logical volume --- LV Path /dev/vg0/lv0 LV Name lv0 VG Name vg0 LV UUID 32AMUw-xgxw-ejJ2-rps1-fm0e-feYw-OoTPS8 LV Write Access read/write LV Creation host, time Centos6.8, 2016-08-27 16:21:48 +0800 LV Status available # open 0 LV Size 3.00 GiB Current LE 768 Segments 1 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 253:0 [19:23 root@Centos6.8~]# mount /dev/vg0/lv0 /mnt/lv0/ #重新挂载 [19:23 root@Centos6.8~]# df -h Filesystem Size Used Avail Use% Mounted on /dev/sda2 48G 4.7G 41G 11% / tmpfs 932M 72K 932M 1% /dev/shm /dev/sda1 190M 39M 142M 22% /boot /dev/sda3 20G 44M 19G 1% /testdir /dev/mapper/vg0-lv0 3.0G 69M 2.8G 3% /mnt/lv0 [19:24 root@Centos6.8~]# ll /mnt/lv0/ #文件正常 total 20 -rw-r--r--. 1 root root 28 Aug 27 19:12 f1 drwx------. 2 root root 16384 Aug 27 19:12 lost+found
逻辑卷快照：
(1)快照是特殊的逻辑卷，它是在生成快照时存在的逻辑卷的准确拷贝
(2)对于需要备份或者复制的现有数据集临时拷贝以及其它操作来说，快照是最合适的选择。
(3)快照只有在它们和原来的逻辑卷不同时才会消耗空间，即一开始创建逻辑卷时，快照的空间其实是空的，这是为什么创建快照速度如此快的原因，快照后虽然理论上是一块空的空间，但实际上会在快照上看到原来的LV内容，但该内容不是存在快照上，而是原来LV的一个指针，只有原来LV内容更改时才会把内容拷贝到快照上。
(4)快照就是将当时的系统信息记录下来，就好像照相一般，若将来有任何数据改动了，则原始数据会被移动到快照区，没有改动的区域则由快照区和文件系统共享。
由于快照区与原本的LV共用很多PE的区块，因此快照去与被快照的LV必须要要在同一个VG上！系统恢复的时候的文件数量不能高于快照区的实际容量。
为现有逻辑卷创建快照 #lvcreate -l 64 -s -n snap-data -p r /dev/vg0/data #-p r，快照一般权限是只读 挂载快照 #mkdir -p /mnt/snap #mount -o ro /dev/vg0/snap-data /mnt/snap 删除快照 #umount /mnt/databackup #lvremove /dev/vg0/databackup
实例：
[10:17 root@Centos6.8/mnt/lv1]# lvcreate -L 1G -n my_snapshot -p r -s /dev/vg1/lv1 Logical volume "my_snapshot" created. [10:17 root@Centos6.8/mnt/lv1]# lvdisplay --- Logical volume --- LV Path /dev/vg1/lv1 LV Name lv1 VG Name vg1 LV UUID tPz7MB-ldJ7-VP0y-BN6c-aUj2-AAlM-5sDvqb LV Write Access read/write LV Creation host, time Centos6.8, 2016-08-30 09:32:54 +0800 LV snapshot status source of my_snapshot [active] LV Status available # open 1 LV Size 3.00 GiB Current LE 192 Segments 1 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 253:0 --- Logical volume --- LV Path /dev/vg1/my_snapshot LV Name my_snapshot VG Name vg1 LV UUID wLc4Sm-hmUM-Kk3R-ImgP-f7dC-Bzt1-TT4zk4 LV Write Access read only LV Creation host, time Centos6.8, 2016-08-30 10:17:24 +0800 LV snapshot status active destination for lv1 LV Status available # open 0 LV Size 3.00 GiB Current LE 192 COW-table size 1.00 GiB COW-table LE 64 Allocated to snapshot 0.00% Snapshot chunk size 4.00 KiB Segments 1 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 253:3 [10:17 root@Centos6.8/mnt/lv1]# mkdir /mnt/napshottest [10:17 root@Centos6.8/mnt/lv1]# mount /dev/vg1/my_snapshot /mnt/sda6/ mount: block device /dev/mapper/vg1-my_snapshot is write-protected, mounting read-only [10:18 root@Centos6.8/mnt/lv1]# mount /dev/vg1/my_snapshot /mnt/sda6/ mount: block device /dev/mapper/vg1-my_snapshot is write-protected, mounting read-only mount: /dev/mapper/vg1-my_snapshot already mounted or /mnt/sda6/ busy mount: according to mtab, /dev/mapper/vg1-my_snapshot is already mounted on /mnt/sda6 [10:18 root@Centos6.8/mnt/lv1]# df Filesystem 1K-blocks Used Available Use% Mounted on /dev/sda2 50264772 5659356 42045416 12% / tmpfs 953648 72 953576 1% /dev/shm /dev/sda1 194241 39020 144981 22% /boot /dev/sda3 20027260 44996 18958264 1% /testdir /dev/mapper/vg1-lv1 3096336 34364 2904712 2% /mnt/lv1 /dev/mapper/vg1-my_snapshot 3096336 34364 2904712 2% /mnt/sda6 [10:19 root@Centos6.8/mnt]# cd lv1/ [10:19 root@Centos6.8/mnt/lv1]# ls f1 inittab lost+found rc.sysinit [10:19 root@Centos6.8/mnt/lv1]# echo > inittab #修改原来逻辑卷文件 [10:20 root@Centos6.8/mnt/lv1]# cat inittab #修改原来逻辑卷文件已经被修改 [10:20 root@Centos6.8/mnt/lv1]# cat /mnt/sda6/inittab #查看快照的文件还是初始状态 # inittab is only used by upstart for the default runlevel. # # ADDING OTHER CONFIGURATION HERE WILL HAVE NO EFFECT ON YOUR SYSTEM. # # System initialization is started by /etc/init/rcS.conf # # Individual runlevels are started by /etc/init/rc.conf # # Ctrl-Alt-Delete is handled by /etc/init/control-alt-delete.conf # # Terminal gettys are handled by /etc/init/tty.conf and /etc/init/serial.conf, # with configuration in /etc/sysconfig/init. # # For information on how to write upstart event handlers, or how # upstart works, see init(5), init(8), and initctl(8). # # Default runlevel. The runlevels used are: # 0 - halt (Do NOT set initdefault to this) # 1 - Single user mode # 2 - Multiuser, without NFS (The same as 3, if you do not have networking) # 3 - Full multiuser mode # 4 - unused # 5 - X11 # 6 - reboot (Do NOT set initdefault to this) # id:5:initdefault:
原创文章，作者：麦德良，如若转载，请注明出处：http://www.178linux.com/42348
评论列表（1条）
内容饱满，但是缺乏了逻辑性，这是作者需要好好培养的地方，同时对于raid部分如果能通过图片来展示各个级别的工作模式会更直观哦。