loop back device with lvm

main usage

1. virtualize a file as an image disk and added it into lvm

conceptions

1. loop back device
2. lvm

practise

pre-requirements

• you need to know basic conceptions
• logical volume manager has been read and practised

purpose

• virtualize a file as an image disk
• add image disk to lvm
• create LV to use the storage

do it

1. prepare a virtual machine according to create centos 8 with qemu
2. create an image file

   • dd if=/dev/zero of=disk.img bs=1M count=1024
     

3. bind with loop back device

   • losetup /dev/loop0 disk.img
     

4. create VG with loop back device

   • vgcreate vgtest /dev/loop0
     

5. create LV

   • lvcreate -L 100M -n data vgtest
     

6. create file system on LV

   • mkfs.xfs /dev/mapper/vgtest-data
     

7. mount and test

   • mount /dev/mapper/vgtest-data /mnt
     df -h
     touch /mnt/test-file
     echo this is a part of testing > /mnt/test-file
     echo this is a another part of testing >> /mnt/test-file
     cat /mnt/test-file