LVM-HOWTO/学习笔记(五)

  

1.         转移一个VG 到另外一个系统

 

Unmount the file system

First, make sure that no users are accessing files on the active volume, then unmount it

# unmount /mnt/design/users

Mark the volume group inactive

Marking the volume group inactive removes it from the kernel and prevents any further activity on it.

# vgchange -an design vgchange -- volume group "design" successfully deactivated

Export the volume group

It is now necessary to export the volume group. This prevents it from being accessed on the ``old'' host system and prepares it to be removed.

# vgexport design vgexport -- volume group "design" successfully exported

Import the volume group

When plugged into the new system it becomes /dev/sdb so an initial pvscan shows:

# pvscan pvscan -- reading all physical volumes (this may take a while...) pvscan -- inactive PV "/dev/sdb1"  is in EXPORTED VG "design" [996 MB / 996 MB free] pvscan -- inactive PV "/dev/sdb2"  is in EXPORTED VG "design" [996 MB / 244 MB free] pvscan -- total: 2 [1.95 GB] / in use: 2 [1.95 GB] / in no VG: 0 [0]

# vgimport design

  Volume group "vg" successfully imported

Activate the volume group

You must activate the volume group before you can access it.

# vgchange -ay design

Mount the file system

# mkdir -p /mnt/design/users # mount /dev/design/users /mnt/design/users

The file system is now available for use.

 

2.         分割一个vg

Determine free space

# pvscan pvscan -- reading all physical volumes (this may take a while...) pvscan -- ACTIVE   PV "/dev/sda"  of VG "dev"   [1.95 GB / 0 free] pvscan -- ACTIVE   PV "/dev/sdb"  of VG "sales" [1.95 GB / 1.27 GB free] pvscan -- ACTIVE   PV "/dev/sdc"  of VG "ops"   [1.95 GB / 564 MB free] pvscan -- ACTIVE   PV "/dev/sdd"  of VG "dev"   [1.95 GB / 0 free] pvscan -- ACTIVE   PV "/dev/sde"  of VG "ops"   [1.95 GB / 1.9 GB free] pvscan -- ACTIVE   PV "/dev/sdf"  of VG "dev"   [1.95 GB / 1.33 GB free] pvscan -- ACTIVE   PV "/dev/sdg1" of VG "ops"   [996 MB / 432 MB free] pvscan -- ACTIVE   PV "/dev/sdg2" of VG "dev"   [996 MB / 632 MB free] pvscan -- total: 8 [13.67 GB] / in use: 8 [13.67 GB] / in no VG: 0 [0]

Move data off the disks to be used

Some space is still used on the chosen volumes so it is necessary to move that used space off onto some others.

Move all the used physical extents from /dev/sdg1 to /dev/sde and from /dev/sdg2 to /dev/sdf

# pvmove /dev/sdg1 /dev/sde pvmove -- moving physical extents in active volume group "ops" pvmove -- WARNING: moving of active logical volumes may cause data loss! pvmove -- do you want to continue? [y/n] y pvmove -- doing automatic backup of volume group "ops" pvmove -- 141 extents of physical volume "/dev/sdg1" successfully moved   # pvmove /dev/sdg2 /dev/sdf pvmove -- moving physical extents in active volume group "dev" pvmove -- WARNING: moving of active logical volumes may cause data loss! pvmove -- do you want to continue? [y/n] y pvmove -- doing automatic backup of volume group "dev" pvmove -- 91 extents of physical volume "/dev/sdg2" successfully moved

Create the new volume group

Now, split /dev/sdg2 from dev and add it into a new group called "design". it is possible to do this using vgreduce and vgcreate but the vgsplit command combines the two.

# vgsplit dev design /dev/sdg2 vgsplit -- doing automatic backup of volume group "dev" vgsplit -- doing automatic backup of volume group "design" vgsplit -- volume group "dev" successfully split into "dev" and "design"

Remove remaining volume

Next, remove /dev/sdg1 from ops and add it into design.

# vgreduce ops /dev/sdg1 vgreduce -- doing automatic backup of volume group "ops" vgreduce -- volume group "ops" successfully reduced by physical volume: vgreduce -- /dev/sdg1   # vgextend design /dev/sdg1 vgextend -- INFO: maximum logical volume size is 255.99 Gigabyte vgextend -- doing automatic backup of volume group "design" vgextend -- volume group "design" successfully extended

Create new logical volume

Now create a logical volume. Rather than allocate all of the available space, leave some spare in case it is needed elsewhere.

# lvcreate -L750M -n users design lvcreate -- rounding up size to physical extent boundary "752 MB" lvcreate -- doing automatic backup of "design" lvcreate -- logical volume "/dev/design/users" successfully created

Make a file system on the volume

# mke2fs /dev/design/users mke2fs 1.18, 11-Nov-1999 for EXT2 FS 0.5b, 95/08/09 Filesystem label= OS type: Linux Block size=4096 (log=2) Fragment size=4096 (log=2) 96384 inodes, 192512 blocks 9625 blocks (5.00<!-- ) reserved for the super user First data block=0 6 block groups 32768 blocks per group, 32768 fragments per group 16064 inodes per group Superblock backups stored on blocks:         32768, 98304, 163840   Writing inode tables: done                            Writing superblocks and filesystem accounting information: done

Mount the new volume

# mkdir -p /mnt/design/users mount /dev/design/users /mnt/design/users/

It's also a good idea to add an entry for this file system in your /etc/fstab file as follows:

/dev/design/user /mnt/design/users   ext2    defaults        1 2