From: Josef Bacik <jbacik@fb.com>
To: Kai Krakow <hurikhan77+btrfs@gmail.com>, <linux-btrfs@vger.kernel.org>
Subject: Re: Are nocow files snapshot-aware
Date: Tue, 4 Feb 2014 20:22:05 -0500 [thread overview]
Message-ID: <52F1923D.8090306@fb.com> (raw)
In-Reply-To: <mh08sa-5tp.ln1@hurikhan77.spdns.de>
On 02/04/2014 03:52 PM, Kai Krakow wrote:
> Hi!
>
> I'm curious... The whole snapshot thing on btrfs is based on its COW design.
> But you can make individual files and directory contents nocow by applying
> the C attribute on it using chattr. This is usually recommended for database
> files and VM images. So far, so good...
>
> But what happens to such files when they are part of a snapshot? Do they
> become duplicated during the snapshot? Do they become unshared (as a whole)
> when written to? Or when the the parent snapshot becomes deleted? Or maybe
> the nocow attribute is just ignored after a snapshot was taken?
>
> After all they are nocow and thus would be handled in another way when
> snapshotted.
>
When snapshotted nocow files fallback to normal cow behaviour. Thanks,
Josef
next prev parent reply other threads:[~2014-02-05 1:22 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-04 20:52 Are nocow files snapshot-aware Kai Krakow
2014-02-05 1:22 ` Josef Bacik [this message]
2014-02-05 2:02 ` David Sterba
2014-02-05 18:17 ` Kai Krakow
2014-02-06 2:38 ` Duncan
2014-02-07 0:32 ` Kai Krakow
2014-02-07 1:01 ` cwillu
2014-02-07 1:28 ` Chris Murphy
2014-02-07 21:07 ` Kai Krakow
2014-02-07 21:31 ` Chris Murphy
2014-02-07 22:26 ` Kai Krakow
2014-02-08 6:34 ` Duncan
2014-02-08 8:50 ` Kai Krakow
2014-02-07 7:06 ` Duncan
2014-02-07 21:58 ` Kai Krakow
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=52F1923D.8090306@fb.com \
--to=jbacik@fb.com \
--cc=hurikhan77+btrfs@gmail.com \
--cc=linux-btrfs@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).