Re: SMR drive test 2; 128GB partition; no obvious corruption, much more sane behaviour, weird overprovisioning

From: Marc Lehmann <schmorp@schmorp.de>
To: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: linux-f2fs-devel@lists.sourceforge.net
Subject: Re: SMR drive test 2; 128GB partition; no obvious corruption, much more sane behaviour, weird overprovisioning
Date: Thu, 24 Sep 2015 01:39:38 +0200	[thread overview]
Message-ID: <20150923233937.GE3463@schmorp.de> (raw)
In-Reply-To: <20150923220823.GE36564@jaegeuk-mac02.mot.com>

On Wed, Sep 23, 2015 at 03:08:23PM -0700, Jaegeuk Kim <jaegeuk@kernel.org> wrote:
> >    root@shag:/sys/fs/f2fs/dm-1# df -H /mnt
> >    Filesystem                Size  Used Avail Use% Mounted on
> >    /dev/mapper/vg_test-test  138G  137G  803k 100% /mnt
> 
> Could you please share /sys/kernel/debug/f2fs/status?

Uh, sorry, I planned to, but forgot, probably because I thought the result
was so good it didn't need any checking :)

> So, I'm convinced that your inital test set "-o1 -s128", which was an unlucky
> trial. :)

hmm... since the point is to simulate a full 8TB partition, having large
overprovision/reserved space AND large section size might actually have been
a good test, as it would simulate the TB case better, which would also have
larger overprovisioning and the larger section size.

In the end, I might settle with -s64, and currently do tests with -s90.

I was just scared that overprovisioning might turn out ot be extremely large
with 8TB.

I have since then dropped -o from all my mkfs.f2fs invocations, seeing
that the resulting filesystem does not actually have 5% overprovisioning.

> Subject: [PATCH] mkfs.f2fs: fix wrong ovp space calculation on large section

Hmm, the latest change in
git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs-tools.git is from
august 10 - do I need to select a branch (I am not good with git)?

-- 
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