[sles-beta] SLES12 beta3 question concerning XFS boot

[Joe Doupnik]

On 01/04/2014 15:12, Matthias G. Eckermann wrote:
> On 2014-04-01 T 13:53 +0000 urs.frey at post.ch wrote:
>   
>> I would like to have a detailed look at all filesystems
>> coming with SLES12, just to be able to know "what I am
>> talking about" ;-D Reason for this is, that some of our
>> application architects like to have /opt for their
>> special purposes (Weblogic, TC-Server ,etc.) But when
>> using BtrFS /opt should be a subvolume for snapshot
>> purposes.
>   
> Well, yes, but:-)
>
> Even if we mount "/opt" as a separate subvolume, you
> _can_ decide to put the whole "/opt" on another
> filesystem, such as xfs.
>
> Please do NOT do this for "/var", "/usr" or other parts,
> if you want to enjoy snapshotting. For "/opt" you will be
> safe, as no parts of the SUSE deliverable should put
> anything onto "/opt" by default.
>
> Now, why did we put "/opt" on a separate subvolume
> nevertheless?
>
> We want to be proactively careful.
>
> Imagine this: someone would put Oracle + data on "/opt"
> and it would be part of "/" on btrfs. If the "someone"
> would roll back, the data would be rolled back as well.
> -> "Not good"™
>
> Thus the safe bet is to put "/opt" on a separate
> subvolume, and an experienced administrator, who knows
> what he does, can decide to have "/opt" separately on
> e.g. xfs.
>
> Enjoy!
>
> so logn -	
> 	MgE
>
-----------
     Yes, indeed. The same reasoning applies to virtual machines where a 
host level snapshot can do the whole machine or omit certain disk drives 
(e.g., VMware independent drives).
     Back in the olden days, /usr/local was for personally installed 
material on BSD, external to the o/s installation. AT&T used /opt for 
the same purpose. Safe havens. Back then /usr was optional at boot time, 
rightly so, and led to /bin, /sbin, and /lib as areas to support booting 
and emergency recovery. /usr was to support interactive mode as the name 
implies. Today the Linux community has forgotten all about that, as well 
that /*/lib were for "lib*" files rather than be "general dumping grounds."
     Ah, how times change. Listen to Matthias.
     Joe D.