Steve Litt - 04.12.23, 00:30:56 CET:
> >The simplist thing wasto put /usr elsewhere on the disk.
> >
> >This whole situation is obsolete now that we have a logical voluume
> >manager, but /usr is still separate for historical reasons.
>
> Logical Volume Manager, AKA LVM, is not a magic bullet. It's a complex
> extra layer of abstraction that can make it harder to get to your data
> if things go wrong.

It is indeed an extra layer of abstraction. My practical experience
however is: I never ever had any problem to get to my data if things go
wrong in probably more than 15 years, probably almost 20 years of LVM
usage on any of my systems including more than half a dozen of laptops and
I don't know how many servers I administered during that time including in
addition to my systems customer systems. I did not have even a single LVM
breakage during that time. Not even one.

Maybe I just got lucky, however given my current practical experience I
see no reason to change my practice of using LVM unless for special setups
or once I might decide to go one filesystem for everything, probably except
swap, like in BTRFS or at one point in time BCacheFS with subvolumes.

I am still old school here and like to have several failure domains
instead of just one. It has proven right again as accidentally my main
laptop hibernated from an outdated memory image - which is in itself a
longer still partly unexplained story of GRUB breaking down during early
testing of BCacheFS in order to write an article about it. It crashed
three of four filesystems due to memory state not matching on disk state,
however as I have separated archival data like music, videos, images onto
another >1TB filesystem the time to restore from backup has been
drastically reduced. Fortunately I was able to update the backup for /home
before recreating the structurally damaged BTRFS filesystem, so that no non
operating system data was lost.

I vgcfgbackup the configuration on my laptops. I never had to restore any
LVM configuration yet (which in itself may be very dangerous in case the
backed up LVM configuration is outdated).

So while I did have some crazy filesystem crashes over the years for
various more or less crazy reasons, LVM never ever let me down so far.

--
Martin