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From: Austin S Hemmelgarn <ahferroin7@gmail.com>
To: Duncan <1i5t5.duncan@cox.net>, linux-btrfs@vger.kernel.org
Subject: Re: Why subvolume and not just volume?
Date: Thu, 6 Aug 2015 07:17:46 -0400	[thread overview]
Message-ID: <55C3425A.7030802@gmail.com> (raw)
In-Reply-To: <pan$26b5e$81e797b6$ee8aa3f0$e575c51a@cox.net>

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On 2015-08-06 03:23, Duncan wrote:
> Martin posted on Wed, 05 Aug 2015 09:06:40 +0200 as excerpted:
>
>> [W]hat is the penalty of a subvolume compared to a directory? From a
>> design perspective, couldn't all directories just be subvolumes?
>
> In addition to the performance issues mentioned by others, there's at
> least one further practical reason as well.
>
> Snapshots stop at subvolume boundaries.  It's thus quite useful to use
> subvolumes to delineate the limits of the snapshot, saying, in effect,
> snapshot this dir (which happens to be a subvol not just a normal dir)
> recursively, but don't snapshot the subtree starting with this nested
> subdir (which again is a (different) subvol).
>
And for some people, this is very useful functionality.  I use it to 
specifically exclude subsets of trivially reproducible data from backups 
(for example, I always clone public git repositories into individual 
subvolumes, and keep my local copy of the Portage tree on a separate one 
(when it isn't on a separate filesystem that is)).


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      reply	other threads:[~2015-08-06 11:18 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-08-05  7:06 Why subvolume and not just volume? Martin
2015-08-05  7:23 ` Qu Wenruo
2015-08-05 17:13 ` David Sterba
2015-08-06  7:23 ` Duncan
2015-08-06 11:17   ` Austin S Hemmelgarn [this message]

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