[sles-beta] default btrfs subvolumes under / in SLES 12

[Matthias G. Eckermann]

Hello Wendy and all,

On 2014-06-27 T 15:25 +0000 Wendy Palm wrote:

> In the default installation of SLES 12, these btrfs
> subvolumes are created underneath /.  Where can I find
> information about why these were chosen to be
> subvolumes?

These have been chosen to not risk anybody to rollback
files which should not be rolled back. Example: rolling
back any file in /var/log/ would lead to compliance
violations with most customers and partners.

That said:
 
> For my use, I have another subvolume to add, 

That depends what you want to add. Can you tell us?

> but also will be removing some of these, 

You really should _not_ remove any of those subvolumes.
If you feel, you need need to, my advice is not to use
rollback at all, as you will run into issues most
probably.

Or to be more strict: if you are removing pre-chosen
subvolumes, your setup will be unsupported for the
rollback usecase - as a general rule. Please be more
specific, what you feel to not have in a subvolume.

> so I would like to understand why these directories
> are in the subvolume list.
 
As said above, these subvolumes contain files which
should not be snapshotted (e.g. /var/crash, /tmp,
/var/tmp) or should be prevented from accidentially been
rolled back (e.g.  /var/log, /var/pgsql, /var/mailman,
/var/spool), directories where third-party data are
stored (/srv, /opt, /var/opt, /var/local) or
directories which contain "static" executables
(/opt/grub2/...). I think I have covered all now.

Can you send some details about your requirements?

so long -
	MgE



>         <partition>
>           <create config:type="boolean">true</create>
>           <crypt_fs config:type="boolean">false</crypt_fs>
>           <filesystem config:type="symbol">btrfs</filesystem>
>           <format config:type="boolean">true</format>
>           <loop_fs config:type="boolean">false</loop_fs>
>           <mount>/</mount>
>           <mountby config:type="symbol">uuid</mountby>
>           <partition_id config:type="integer">131</partition_id>
>           <partition_nr config:type="integer">2</partition_nr>
>           <resize config:type="boolean">false</resize>
>           <size>42944593408</size>
>           <subvolumes config:type="list">
>             <listentry>boot/grub2/i386-pc</listentry>
>             <listentry>boot/grub2/x86_64-efi</listentry>
>             <listentry>opt</listentry>
>             <listentry>srv</listentry>
>             <listentry>tmp</listentry>
>             <listentry>usr/local</listentry>
>             <listentry>var/crash</listentry>
>             <listentry>var/lib/mailman</listentry>
>             <listentry>var/lib/named</listentry>
>             <listentry>var/lib/pgqsl</listentry>
>             <listentry>var/log</listentry>
>             <listentry>var/opt</listentry>
>             <listentry>var/spool</listentry>
>             <listentry>var/tmp</listentry>
>           </subvolumes>
>         </partition>



-- 
Matthias G. Eckermann     Senior Product Manager   SUSE® Linux Enterprise
Phone: +49 30 44315731    Mobile: +49 179 2949448    E-Mail: mge at suse.com
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