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Before proceeding, ensure that:

• You have CentOS 7 installed.
• You have superuser privileges or sudo access.
• You understand basic concepts of LVM.

1. Preparing the System

Before setting up the snapshot, it's important to check the current status of LVM and ensure that there is enough free space to create a snapshot.

lvmdiskscan
vgdisplay

These commands will display available disks and the current status of volume groups, including free space.

2. Creating an LVM Snapshot

If there is sufficient free space, proceed to create an LVM snapshot. The example below demonstrates creating a 1GB snapshot for a logical volume named lv_data in the volume group vg_system.

lvcreate -L 1G -s -n lv_snapshot -p r /dev/vg_system/lv_data

• -L 1G specifies the size of the snapshot.
• -s indicates that it is a snapshot.
• -n lv_snapshot sets the name of the snapshot.
• -p r specifies that the snapshot will be read-only.

3. Mounting the Snapshot

After creating the snapshot, you can mount it and verify its contents.

mkdir /mnt/snapshot
mount -o ro /dev/vg_system/lv_snapshot /mnt/snapshot

Using the -o ro flag ensures that the snapshot is mounted as read-only, meaning data cannot be written to it.

4. Testing Recovery

With the snapshot mounted, you can now test the recovery process. This may involve copying files from the mounted snapshot to the original location or another destination, depending on your testing scenarios.

5. Unmounting and Removing the Snapshot

After completing the tests, remember to unmount and remove the snapshot to free up space.

umount /mnt/snapshot
lvremove /dev/vg_system/lv_snapshot

Utilizing LVM snapshots as read-only for testing backup recovery on CentOS 7 allows you to safely validate your backup procedures without risking damage to the original data. This approach is beneficial for administrators seeking an efficient method to test and verify backups with minimal impact on production environments.