A Snapshot vs a Backup
Many have not understood what is a snapshot? What are the differences? Which is better? Today, we are here to explain to you the differences, the pros and cons of the backups and the snapshots.
Snapshot is only available to a VM. Whether they are called VPS or something else. If the instance is virtualized, a snapshot is possible. Backup is installing an agent into the guest OS or the dedicated server, transfer the partition or files into a backup storage device.
Snapshot takes an image of the instance of its current state and dumped into a compressed file format like LZO. It is only possible to restore the entire VM. to restore files, you will have to extract files after you have restored the VM to another instance which is very time-consuming.
However, you can restore files from a backup. Even a bootable partition for some backup solutions. To restore a partition, you must have a temp portable partition on the memory to restore the restored bootable partition backup. This is a very slow process especially the restoration involved a huge partition.
Files restoration is the fastest and if you need to roll back the entire server, a snapshot restoration is much faster than restoring a bootable partition. However, if your backup retention is longer, you will need lesser space on your backup devices.
Most snapshot use NFS. It is cheaper to build an NFS storage than a proprietary backup solution. Nowadays, VM snapshot uses LVM-Thin to conserve disk space, it helps reduce disk space usage significantly. There is a drawback using LVM-Thin, the server must have a faster write and read space especially restoration, otherwise, it will affect the speed on other guest machines on the same server.