[CentOS] C7 live CD does not like F33 ext partition

Wed Apr 21 01:37:09 UTC 2021
Robert Heller <heller at deepsoft.com>

At Tue, 20 Apr 2021 20:19:47 -0500 (CDT) CentOS mailing list <centos at centos.org> wrote:

> 
> On Tue, 20 Apr 2021, Michael Hennebry wrote:
> 
> > I've been trying to backup the root partition of my F33 installation.
> > To that end, I'm running a C7 live CD.
> > C7 won't mount the partition.
> > tune2fs likes it, but
> > [root at localhost mnt]# mount /dev/sda5 /mnt/a5
> > mount: wrong fs type, bad option, bad superblock on /dev/sda5,
> >       missing codepage or helper program, or other error
> >
> >       In some cases useful info is found in syslog - try
> >       dmesg | tail or so.
> > [root at localhost mnt]# dmesg | tail -n 15
> 
> > [  146.548540] Bluetooth: BNEP socket layer initialized
> > [  300.961319] JBD2: Unrecognised features on journal
> > [  300.961325] EXT4-fs (sda5): error loading journal   ====== WHY?
> > [  361.930877] e1000e: enp0s25 NIC Link is Up 1000 Mbps Full Duplex, Flow
> 
> I just ran fsck -n /dev/sda5 .
> [root at localhost mnt]# fsck -n /dev/sda5
> fsck from util-linux 2.23.2
> e2fsck 1.42.9 (28-Dec-2013)
> Journal superblock has an unknown incompatible feature flag set.
> Abort? no
> 
> Journal superblock is corrupt.
> Fix? no
> 
> fsck.ext4: The ext2 superblock is corrupt while checking ext3 journal for slash
> 
> slash: ********** WARNING: Filesystem still has errors **********
> 
> [root at localhost mnt]#
> 
> What is going on?
> What can I do about it?
> 
> Does "unknown incompatible feature flag set" imply corrupt?

No. F33 is just using a newer version of ext4 than C7 understands. You need a
F33 live CD or some other "newer" live CD. A C8 Live CD might work. A Ubuntu
20.04 Live CD will likely work.


> How dangerous would it be to let fsck fix it?
> 
> I'm starting to think I might need to back up / while it is in use.

Nothing terribly wrong with that...  You might not be able to backup log files 
if they change during the backup, but that is hardly fatal.  You want to use 
something like tar and not dump...

> 

-- 
Robert Heller             -- Cell: 413-658-7953 GV: 978-633-5364
Deepwoods Software        -- Custom Software Services
http://www.deepsoft.com/  -- Linux Administration Services
heller at deepsoft.com       -- Webhosting Services