From: Hugo Mills <hugo@carfax.org.uk>
To: Martin Steigerwald <martin@lichtvoll.de>
Cc: linux-btrfs@vger.kernel.org
Subject: Re: Small fs
Date: Sun, 11 Sep 2016 19:46:32 +0000 [thread overview]
Message-ID: <20160911194632.GF7138@carfax.org.uk> (raw)
In-Reply-To: <14309857.N6fGUh6qoJ@merkaba>
[-- Attachment #1: Type: text/plain, Size: 1251 bytes --]
On Sun, Sep 11, 2016 at 09:13:28PM +0200, Martin Steigerwald wrote:
> Am Sonntag, 11. September 2016, 16:44:23 CEST schrieb Duncan:
> > * Metadata, and thus mixed-bg, defaults to DUP mode on a single-device
> > filesystem (except on ssd where I actually still use it myself, and
> > recommend it except for ssds that do firmware dedupe). In mixed-mode
> > this means two copies of data as well, which halves the usable space.
> >
> > IOW, when using mixed-mode, which is recommended under a gig, and dup
> > replication which is then the single-device default, effective usable
> > space is **HALVED**, so 256 MiB btrfs size becomes 128 MiB usable. (!!)
>
> I don´t get this part. That is just *metadata* being duplicated, not the
> actual *data* inside the files. Or am I missing something here?
In mixed mode, there's no distinction: Data and metadata both use
the same chunks. If those chunks are DUP, then both data and metadata
are duplicated, and you get half the space available.
Hugo.
--
Hugo Mills | Questions are a burden, and answers a prison for
hugo@... carfax.org.uk | oneself
http://carfax.org.uk/ |
PGP: E2AB1DE4 | The Prisoner
[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 836 bytes --]
next prev parent reply other threads:[~2016-09-11 19:46 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-11 15:27 Small fs Imran Geriskovan
2016-09-11 15:32 ` Martin Steigerwald
2016-09-11 16:44 ` Duncan
2016-09-11 18:56 ` Imran Geriskovan
2016-09-11 19:21 ` Martin Steigerwald
2016-09-12 12:41 ` Austin S. Hemmelgarn
2016-09-12 14:09 ` Henk Slager
2016-09-12 14:12 ` Austin S. Hemmelgarn
2016-09-12 14:51 ` Chris Murphy
2016-09-12 14:56 ` Austin S. Hemmelgarn
2016-09-12 3:33 ` Duncan
2016-09-12 14:11 ` Imran Geriskovan
2016-09-12 17:43 ` Imran Geriskovan
2016-09-12 18:46 ` Imran Geriskovan
2016-09-12 18:55 ` Austin S. Hemmelgarn
2016-09-12 21:32 ` Mike Fleetwood
2016-09-11 19:13 ` Martin Steigerwald
2016-09-11 19:46 ` Hugo Mills [this message]
2016-09-11 19:51 ` Martin Steigerwald
2016-09-12 12:45 ` Austin S. Hemmelgarn
2016-09-11 20:33 ` Chris Murphy
2016-09-12 2:00 ` Duncan
2016-09-12 3:03 ` Chris Murphy
2016-09-12 4:54 ` Duncan
2016-09-12 14:48 ` Chris Murphy
2016-09-13 4:25 ` Duncan
2016-09-12 12:54 ` Imran Geriskovan
2016-09-12 13:01 ` Austin S. Hemmelgarn
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=20160911194632.GF7138@carfax.org.uk \
--to=hugo@carfax.org.uk \
--cc=linux-btrfs@vger.kernel.org \
--cc=martin@lichtvoll.de \
/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).