[sles-beta] [ ] Re: btrfs & tooling

[Matthias G. Eckermann]

Hello Mr. Schumacher and all,

On 2014-09-29 T 15:30 +0200 Christoph Schumacher wrote:

> Basically there should be a tool showing usage as df
> does for subvolumes human readable at a glance.  I'll
> talk to Ralf Dannert on the workshop in Nuremberg on
> Wednesday.
 
as I will not be in Nürnberg at the workshop either, I
was curious about the Use Case (as some of you might
have been). And the Use Case is as a classic one:
monitor /tmp and /var/log for their size, and prevent
these subdirectories (or subvolumes) from filling the
whole filesystem.

Now, there are two ways to solve this Use Case.

1. Use btrfs subvolumes and quota groups. As seen, this
   has issues, specifically in the way how to "account",
   and how to use the tools. For obvious reasons (see
   Jeff's mails), a simple "df" does not work in the 
   context of any CoW filesystem (btrfs is not alone
   here!), thus we have to come up with a good "how to",
   and improved output of our tools.

   This is an action item I take to drive with our
   engineering teams after the release of SUSE Linux
   Enterprise 12.

2. Put /tmp and /var/log on separate partitions or
   filesystems, as many have done in the past. 

   This may raise the question, which subdirectories
   can be put on separate partitions / filesystems
   without impacting Snapshot/Rollback? The answer is
   as simple as obvious: those subdirectories which our
   default partitioning puts on a separate _subvolume_
   can also be placed on a separate _partition_ (with
   the exception of the bootloader related subvolumes).
   
   The SUSE Linux Enterprise Server 12 Release Notes
   have a comprehensive list; see:
   https://www.suse.com/releasenotes/x86_64/SUSE-SLES/12/#fate-316522

Hope this helps!

so long -
	MgE


-- 
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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