You shouldn't use the Linux dump
program any more (on extN filesystems)
When I upgraded my office workstation to Fedora 32, one of the things that happened is that Amanda backups of its root filesystem stopped working. The specific complaint from Amanda was a report of:
no size line match in /usr/lib64/amanda/rundump (xfsdump) output
This happened because of Fedora bug 1830320, adequately
summarized as "ext4 filesystem dumped with xfsdump instead of dump".
The cause of this is that Fedora 32's Amanda RPMs are built without
the venerable dump
program and
so do not try to use it. Instead, if you tell Amanda to back up a
filesystem using the abstract program "DUMP"
, Amanda always uses
xfsdump regardless of what the filesystem type is, and naturally
xfsdump fails on extN filesystems.
I have historically used various versions of the Unix *dump
family of programs because I felt that a
filesystem specific tool was generally going to do the best job of
fully backing up your filesystem, complete with whatever peculiar
things it had (starting with holes in your files). ZFS has no
zfsdump
(although I wish that it did),
so most of my workstation's filesystems are backed up with tar
,
but my root filesystem is an extN one and I used dump
. Well, I
used to use dump
.
At first I was irritated with Fedora packaging and planned to say
grumpy things about it. But then I read more, and discovered that
this Amanda change is actually a good idea, because using Linux
dump
isn't a good idea any more. The full story is in Fedora
bug 1884602,
but the short version is that dump
hasn't been updated to properly
handle modern versions of extN filesystems and won't be, because
it's unmaintained. To quote the bug:
Looking at the code it is very much outdated and will not support current ext4 features, in some cases leading to corrupted files without dump/restore even noticing any problems.
Fedora is currently planning to keep the restore
program around
so that you can restore any dump
archives you have, which I fully
support (especially since the Linux restore
is actually pretty
good at supporting various old dump
formats from other systems,
which can be handy).
I have some reflexes around using 'dump | restore
' pipelines to
copy extN filesystems around (eg,
and also), which I now need to change.
Probably tar
is better than rsync
for this particular purpose.
(I'll miss dump
a bit, but a backup program that can silently produce
corrupted backups is not a feature.)
PS: dump
is a completely different thing than dumpe2fs
; the
former makes backups and the latter tells you details about your
extN filesystem. Dumpe2fs is part of e2fsprogs and naturally remains under
active development as part of extN development.
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