Resizing LVM Logical Volumes-lvextend

1. fdisk命令/dev/sdc再分出一个sdc2分区

[root@rhel7 ~]# fdisk /dev/sdc
Welcome to fdisk (util-linux 2.23.).

Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.

Command (m for help): n
Partition type:
   p   primary ( primary,  extended,  free)
   e   extended
Select (default p): p
Partition number (-, default ):
First sector (-, default ):
Using default value
Last sector, +sectors or +size{K,M,G} (-, default ): +200M
Partition  of type Linux and of size  MiB is set

Command (m for help): t
Partition number (,, default ):
Hex code (type L to list all codes): L

   Empty             NEC DOS           Minix / old Lin bf  Solaris
   FAT12             Hidden NTFS Win   Linux swap / So c1  DRDOS/sec (FAT-
   XENIX root        Plan             Linux           c4  DRDOS/sec (FAT-
   XENIX usr       3c  PartitionMagic    OS/ hidden C:  c6  DRDOS/sec (FAT-
   FAT16 <32M        Venix        Linux extended  c7  Syrinx
   Extended          PPC PReP Boot     NTFS volume set da  Non-FS data
   FAT16             SFS               NTFS volume set db  CP/M / CTOS / .
   HPFS/NTFS/exFAT 4d  QNX4.x            Linux plaintext de  Dell Utility
   AIX             4e  QNX4.x 2nd part 8e  Linux LVM       df  BootIt
   AIX bootable    4f  QNX4.x 3rd part   Amoeba          e1  DOS access
 a  OS/ Boot Manag   OnTrack DM        Amoeba BBT      e3  DOS R/O
 b  W95 FAT32         OnTrack DM6 Aux 9f  BSD/OS          e4  SpeedStor
 c  W95 FAT32 (LBA)   CP/M            a0  IBM Thinkpad hi eb  BeOS fs
 e  W95 FAT16 (LBA)   OnTrack DM6 Aux a5  FreeBSD         ee  GPT
 f  W95 Ext'd (LBA) 54  OnTrackDM6      a6  OpenBSD         ef  EFI (FAT-12/16/
  OPUS              EZ-Drive        a7  NeXTSTEP        f0  Linux/PA-RISC b
  Hidden FAT12      Golden Bow      a8  Darwin UFS      f1  SpeedStor
  Compaq diagnost 5c  Priam Edisk     a9  NetBSD          f4  SpeedStor
  Hidden FAT16 <   SpeedStor       ab  Darwin boot     f2  DOS secondary
  Hidden FAT16      GNU HURD or Sys af  HFS / HFS+      fb  VMware VMFS
  Hidden HPFS/NTF   Novell Netware  b7  BSDI fs         fc  VMware VMKCORE
  AST SmartSleep    Novell Netware  b8  BSDI swap       fd  Linux raid auto
1b  Hidden W95 FAT3   DiskSecure Mult bb  Boot Wizard hid fe  LANstep
1c  Hidden W95 FAT3   PC/IX           be  Solaris boot    ff  BBT
1e  Hidden W95 FAT1   Old Minix
Hex code (type L to list all codes): 8e
Changed type of partition 'Linux' to 'Linux LVM'

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
   g   create a new empty GPT partition table
   G   create an IRIX (SGI) partition table
   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.

WARNING: Re-reading the partition table failed with error : 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() or kpartx()
Syncing disks.  --reboot一下生效

[root@rhel7 ~]# fdisk -l /dev/sdc  --查看/dev/sdc分区情况

Disk /dev/sdc:  MB,  bytes,  sectors
Units = sectors of  *  =  bytes
Sector size (logical/physical):  bytes /  bytes
I/O size (minimum/optimal):  bytes /  bytes
Disk label type: dos
Disk identifier: 0x0c16d904

   Device Boot      Start         End      Blocks   Id  System
/dev/sdc1                           8e  Linux LVM
/dev/sdc2                         8e  Linux LVM
[root@rhel7 ~]# 

2.创建物理卷pv

[root@rhel7 ~]# pvcreate /dev/sdc2   #没有pvextend的说法
  Physical volume "/dev/sdc2" successfully created
[root@rhel7 ~]# pvs
  PV         VG     Fmt  Attr PSize   PFree
  /dev/sda2  rhel   lvm2 a--   .51g  40.00m
  /dev/sdc1  vgdate lvm2 a--   96.00m   4.00m
  /dev/sdc2         lvm2 ---  200.00m 200.00m
[root@rhel7 ~]# 

3.增加VG大小：（把上面创建的pv添加到vg里就行）

[root@rhel7 ~]# vgs
  VG     #PV #LV #SN Attr   VSize  VFree
  rhel            wz--n- .51g 40.00m
  vgdate          wz--n- 96.00m  4.00m
[root@rhel7 ~]# vgdisplay vgdate
  --- Volume group ---
  VG Name               vgdate
  System ID
  Format                lvm2
  Metadata Areas
  Metadata Sequence No
  VG Access             read/write
  VG Status             resizable
  MAX LV
  Cur LV
  Open LV
  Max PV
  Cur PV
  Act PV
  VG Size               96.00 MiB
  PE Size               4.00 MiB
  Total PE
  Alloc PE / Size        / 92.00 MiB
  Free  PE / Size        / 4.00 MiB
  VG UUID               hNTqaY-c0Hi-v5wk-p7lQ-TIbc-oSpm-TIOcHs

[root@rhel7 ~]# vgextend vgdate /dev/sdc2     ---向卷组vgdata中添加pv。没有加多少M或多少G进来的说法，只能把整个PV添加到卷组中来。
  Volume group "vgdate" successfully extended
[root@rhel7 ~]# vgs
  VG     #PV #LV #SN Attr   VSize   VFree
  rhel            wz--n-  .51g  40.00m
  vgdate          wz--n- 292.00m 200.00m
[root@rhel7 ~]# vgdisplay vgdate
  --- Volume group ---
  VG Name               vgdate
  System ID
  Format                lvm2
  Metadata Areas
  Metadata Sequence No
  VG Access             read/write
  VG Status             resizable
  MAX LV
  Cur LV
  Open LV
  Max PV
  Cur PV
  Act PV
  VG Size               292.00 MiB
  PE Size               4.00 MiB
  Total PE
  Alloc PE / Size        / 92.00 MiB
  Free  PE / Size        / 200.00 MiB
  VG UUID               hNTqaY-c0Hi-v5wk-p7lQ-TIbc-oSpm-TIOcHs

[root@rhel7 ~]# 

4.增加LV的大小

[root@rhel7 ~]# lvdisplay vgdate
  --- Logical volume ---
  LV Path                /dev/vgdate/lvvol1
  LV Name                lvvol1
  VG Name                vgdate
  LV UUID                dt10du-dTAJ-0gUV-LqrO-wRUY-rb5h-171DCr
  LV Write Access        read/write
  LV Creation host, time rhel7.com, -- :: -
  LV Status              available
  # open
  LV Size                92.00 MiB
  Current LE
  Segments
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to
  Block device           :

[root@rhel7 ~]# lvextend -L+200MB /dev/vgdate/lvvol1    --给逻辑卷lvvol1增加200MB的空间。如果写成-L 200M，则表示把逻辑卷扩大至200M。
或者lvextend /dev/vgdate/lvvol1 /dev/sdc2 将把/dev/sdc2这个pv剩余的所有空间都分配给逻辑卷lvvol1。
  Size of logical volume vgdate/lvvol1 changed from 92.00 MiB ( extents) to 292.00 MiB ( extents).
  Logical volume lvvol1 successfully resized.
[root@rhel7 ~]# lvdisplay vgdate
  --- Logical volume ---
  LV Path                /dev/vgdate/lvvol1
  LV Name                lvvol1
  VG Name                vgdate
  LV UUID                dt10du-dTAJ-0gUV-LqrO-wRUY-rb5h-171DCr
  LV Write Access        read/write
  LV Creation host, time rhel7.com, -- :: -
  LV Status              available
  # open
  LV Size                292.00 MiB    ---LV size已增加至292MB
  Current LE
  Segments
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to
  Block device           :

[root@rhel7 ~]# 

也可以使用lvresize命令来增加lv的大小：

■lvresize -r -l 75%VG /dev/vgdata/lvdata This resizes the logical volume so that it will take 75% of the total disk space in the volume group.
■ lvresize -r -l +75%VG /dev/vgdata/lvdata This tries to add 75% of the total size of the volume group to the logical volume. (Notice the difference with the previous command.)
■ lvresize -r -l +75%FREE /dev/vgdata/lvdata This adds 75% of all free disk space to the logical volume.
■ lvresize -r -l 75%FREE /dev/vgdata/lvdata This resizes the logical volume to a total size that equals 75% of the amount of free disk space. (Notice the difference with the previous command.)

 5. 增加了逻辑卷的容量以后，就需要修改文件系统大小以实现利用扩充的空间

从上面可以看到，虽然LV大小已增加至292MB，但是使用df -hT命令查看到的文件系统/dev/mapper/vgdate-lvvol1的大小没变，还是89M，所以还需要修改文件系统的大小才可以使用扩充的空间。

[root@rhel7 ~]# df -hT
Filesystem                Type      Size  Used Avail Use% Mounted on
/dev/mapper/rhel-root     xfs        18G  .5G   13G  % /
devtmpfs                  devtmpfs  911M       911M   % /dev
tmpfs                     tmpfs     921M       921M   % /dev/shm
tmpfs                     tmpfs     921M  8.4M  912M   % /run
tmpfs                     tmpfs     921M       921M   % /sys/fs/cgroup
/dev/mapper/vgdate-lvvol1 xfs        89M  4.8M   84M   6% /lvmFiles
/dev/sdd1                 xfs       497M  124M  374M  % /boot
tmpfs                     tmpfs     185M       185M   % /run/user/

使用xfs_growfs命令扩展文件系统。注意这个命令只能用来扩展xfs格式的文件系统，xfs格式是RHEL7版本默认的文件系统，所以用得比较少。

DESCRIPTION
       xfs_growfs  expands  an  existing  XFS  filesystem  (see  xfs()).   The mount-point argument is the pathname of the directory where the
       filesystem is mounted. The filesystem must be mounted to be grown (see mount()).  The existing contents of the  filesystem  are  undis‐
       turbed, and the added space becomes available for additional file storage.

还有另外一个命令resize2fs也是用来扩展文件系统，但是只能用来扩展ext2,ext3,ext4格式的文件系统大小，在RHEL7版本以下的系统中用得比较多。

[root@rhel7 ~]# man resize2fs
RESIZE2FS()                                                System Manager's Manual                                                RESIZE2FS(8)

NAME
       resize2fs - ext2/ext3/ext4 file system resizer

SYNOPSIS
       resize2fs [ -fFpPM ] [ -d debug-flags ] [ -S RAID-stride ] device [ size ]

DESCRIPTION
       The  resize2fs  program  will  resize  ext2,  ext3,  or ext4 file systems.  It can be used to enlarge or shrink an unmounted file system
       located on device.  If the filesystem is mounted, it can be used to expand the size of the mounted filesystem, assuming the kernel  sup‐
       ports  on-line  resizing. 

如果在xfs格式的文件系统中使用resize2fs命令，则会报如下错误：

[root@rhel7 ~]# resize2fs /dev/mapper/vgdate-lvvol1
resize2fs 1.42. (-Dec-)
resize2fs: Bad magic number in super-block while trying to open /dev/mapper/vgdate-lvvol1
Couldn't find valid filesystem superblock.
[root@rhel7 ~]# resize2fs -f /dev/mapper/vgdate-lvvol1
resize2fs 1.42. (-Dec-)
resize2fs: Bad magic number in super-block while trying to open /dev/mapper/vgdate-lvvol1
Couldn't find valid filesystem superblock.

使用xfs_growfs命令扩展文件系统大小：

[root@rhel7 ~]# xfs_growfs /dev/mapper/vgdate-lvvol1
meta-data=/dev/mapper/vgdate-lvvol1 isize=    agcount=, agsize= blks
         =                       sectsz=   attr=, projid32bit=
         =                       crc=        finobt=
data     =                       bsize=   blocks=, imaxpct=
         =                       sunit=      swidth= blks
naming   =version               bsize=   ascii-ci= ftype=
log      =internal               bsize=   blocks=, version=
         =                       sectsz=   sunit= blks, lazy-count=
realtime =none                   extsz=   blocks=, rtextents=
data blocks changed from  to
[root@rhel7 ~]# df -hT
Filesystem                Type      Size  Used Avail Use% Mounted on
/dev/mapper/rhel-root     xfs        18G  .5G   13G  % /
devtmpfs                  devtmpfs  911M       911M   % /dev
tmpfs                     tmpfs     921M       921M   % /dev/shm
tmpfs                     tmpfs     921M  8.4M  912M   % /run
tmpfs                     tmpfs     921M       921M   % /sys/fs/cgroup
/dev/mapper/vgdate-lvvol1 xfs       289M  5.1M  284M   % /lvmFiles   ----------已扩展完成
/dev/sdd1                 xfs       497M  124M  374M  % /boot
tmpfs                     tmpfs     185M       185M   % /run/user/