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 |
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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 |
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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 |
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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] |
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# vgimport design Volume group "vg" successfully importedActivate the volume group
You must activate the volume group before you can access it.
# vgchange -ay design |
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Mount the file system
# mkdir -p /mnt/design/users # mount /dev/design/users /mnt/design/users |
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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] |
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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 |
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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" |
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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 |
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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 |
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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 |
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Mount the new volume
# mkdir -p /mnt/design/users mount /dev/design/users /mnt/design/users/ |
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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 |
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