[Discuss] Backing up the entire software installation

[Rich Pieri]

On Thu, 25 Oct 2018 18:50:16 -0400 (EDT)
Robert Krawitz <rlk at alum.mit.edu> wrote:

> Are you referring to the unwritten/delayed extents bug
> (e. g. https://bugzilla.redhat.com/show_bug.cgi?id=1223332)?  That was
> fixed over 3 years ago
> (https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ce879f96b5).

One of my encounters with extent corruption was probably this, but I've
had other encounters with corrupt extents after this fix was applied.
The most recent was summer or fall 2017 on RHEL 7.3 and deliberate
because we were trying to identify a different ext4 corruption bug
which turned out to be two bugs, one in ext4 and one in VFS.

My recommendation not to use ext4 is less about the corruption
problems, though, and more about the inability to identify and repair
the damage. fsck cannot tell you what files are affected because that
information is what's damaged. Since it cannot identify what's affected
it cannot effect repairs, either. You have to wipe and restore from
backups made prior to the corruption.

-- 
Rich Pieri