Re: SLES 11 SP4: can't mount btrfs

["Austin S. Hemmelgarn" <ahferroin7@gmail.com>]

On 2017-10-24 10:12, Andrei Borzenkov wrote:
> On Tue, Oct 24, 2017 at 2:53 PM, Austin S. Hemmelgarn
> <ahferroin7@gmail.com> wrote:
>>
>> SLES (and OpenSUSE in general) does do something special though, they use
>> subvolumes and qgroups to replicate multiple independent partitions (which
>> is a serious pain in the arse), and they have snapshotting with snapper by
>> default as well.  On OpenSUSE at least you can dispense with all that crap
>> by telling the installer to not enable snapshot support, not sure about SLES
>> though.
> 
> SUSE is using so many subvolumes because
> a) it wants to use snapshot of operating system to enable rollback
> b) data that needs to be part of snapshot includes RPM database
> c) RPM database is located on /var
> 
> So they were forced to make /var part of root subvolume and explicitly
> exclude everything below /var by making it separate subvolumes.
> 
> Fortunately it is going to change now with both RH and SUSE moving RPM
> database under /usr. Which leaves you basically with / and /var as
> default subvolumes.
> 
And /tmp, and /opt, and /usr/local, etc.  With /var as one subvolume, I 
still count at least 8.

That said, the issue I have with it is not as much the number, as the 
choice of layout (the whole /@ crap is ridiculous), and the fact that 
qgroups are enabled by default and not very well documented anywhere 
that I could find (seriously, this needs to be better documented, it 
took me an hour despite my background with BTRFS and as a system 
administrator to figure out why I couldn't fill the disk completely 
anywhere to wipe free space with zeroes so I could compact the disk 
image for the VM I was using).