XFS and btrfs filesystem

the_bro

Whilst reading the lesson on the above, the following questions/observations came to mind:
1. what's the difference between a snapshot and a backup -- or are the terms interchangeable; my understanding is that the former is a lot quicker to complete, so if they are different, can I do a snapshot and just use it as my backup?
2. are the commands xfsdump and xfsrestore snapshot-related commands? The man page describes them as "incremental" which implies the snapshot process...

In terms of readability, the warning text on the btrfs page reads:
btrfs was removed... it is not recommended to use an important filesystem...

I think that should either read:
...it is not recommended to use an imported filesystem...
or
...it is not recommended to use as an important filesystem...

Thoughts, anyone?

coop

The expression "snapshot" means something you can easily revert to, reset the system to. A "backup" does not have this property although it will have all the data to do so, and some forms of backup are indeed images that can be dropped in just like a snapshot. But they are not logically the same.

xfsdump and xfsrestore are, I believe, commands to restore backups, not snapshots, and the restore has a lot of options about what can be deleted, ignored etc. I've never used the commands and the man pages are not crystal clear

Yes the word "as" is missing (your second choice) (use as an important filesystem)

fcioanca

This has been updated in the course. Thank you for flagging it.

cfuchs

Re 1.

• in my understanding (as a btrfs user), a snapshot shares the physical media of the original (and may to a large extend even overlap with the original), a backup is separate (either just duplicated on the same physical media, or on remote media).
• so a snapshot is purely logical (not guaranteed to have any separate space in the physical world), while a backup is physical (guaranteed to occupy a different space in the physical world - even if it is only a separate portion of the physical carrier).