Recently, I was working on a basic construction project, which involved a problem of extending VG.
There is nothing wrong with extending the VG itself, but it seems a little special to the problem I encountered. . .
Phenomenon:
When installing a Linux virtual machine, there was a 200G disk, but only 160G was used when partitioning, leaving 40G, and then the 160G disk was made into LVM, and now I hope to add the unused 40G to the VG (volume group) inside.
Investigation: In order to do the above, I found some information on the Internet. Understand the principle and configuration process of LVM
1. Create a logical volume
①Format the physical hard disk into PV (physical volume) using the pvcreate command
②Create a volume group (VG) and add PV to the volume group through the vgcreate command
③ Create a logical volume (LV) based on the volume group (VG) through the lvcreate command
2. Use formatted logical volumes
mkfs.ext4 /dev/xiaoluo/mylv
3. Delete the logical volume
① First unmount the logical volume in use through the umount command
②Delete the logical volume first through the lvremove command
③ Delete the volume group through the vgremove command
④ Finally, delete our physical volume through the pvremove command
4. Stretch the logical volume (stretching of the logical volume can be done online, no need to unmount to the logical volume)
①Check the information of the current VG and ensure that there is enough free space in the VG through the vgdisplay or vgs command
②Extend the logical volume through the lvextend command
③ After viewing the expansion, after the LV size is expanded, we can use the lvdisplay or lvs command to view the current lv information
④Update the file system through the resize2fs command
5. Stretch roll set
①Format the hard disk to be added to the VG as PV through the pvcreate command
②Add the new PV to the specified VG through the vgextend command
③ View the information of the current VG through the vgdisplay or vgs command
6. Shrink the logical volume
①Unmount the mounted logical volume through the umount command
② Shrink the file system (you will be prompted to run fsck to check the file system) through the resize2fs command
③Reduce LV through lvreduce command
The operation of shrinking a logical volume is a dangerous operation. If we are not careful, our logical volume may be damaged, resulting in the loss or damage of files, so we generally do not shrink the logical volume! ! !
Finally, one more point: the operation of shrinking the logical volume must first unmount the logical volume, then shrink the file system first, and finally shrink our logical volume! !
7. Shrink the volume group
①First of all, we must also unmount our logical volume through the umount command
②Remove a PV from the specified volume group through the vgreduce command
③ View the information of the current volume group through the vgdisplay or vgs command
④Delete the PV through the pvremove command
Envisioned solution:
Based on the above learning, I plan to make the remaining 40G a virtual device first. So the above phenomenon is simulated locally.
1. Add a new disk /dev/sdd (16G)
2. Divide the disk into two logical partitions /dev/sdd1(4G), /dev/sdd2(8G)
3. Make these two partitions into PV, which can be successfully made
4. Based on the above pv, create a volume group VG
5. Create LV based on VG
6. Make the remaining 4G in /dev/sdd into /dev/sdd3, and use the Pvcreate command to create a physical volume, and it prompts that the creation cannot be successful. It seems that there is no way to put the remaining 4G into the volume group.
7. Recreate a virtual disk /dev/sde. The pvcreate command creates a physical volume, which can be successfully created or added to the VG.
result:
Unsuccessful : Make the remaining 4G in /dev/sdd into /dev/sdd3, and use the Pvcreate command to create a physical volume, and it prompts that the creation cannot be successful. It seems that there is no way to put the remaining 4G into the volume group.
Success: recreate a virtual disk /dev/sde, pvcreate command creates a physical volume, which can be successfully created or added to VG
refer to:
The documentation below is really well written and detailed
http://www.cnblogs.com/xiaoluo501395377/archive/2013/05/22/3093405.html
CentOS for Linux Learning (26)--Linux Disk Management: Creation and Use of LVM Logical Volumes