From mboxrd@z Thu Jan  1 00:00:00 1970
From: NeilBrown <neilb@suse.de>
Subject: Re: Data offset
Date: Fri, 16 May 2014 08:07:46 +1000
Message-ID: <20140516080746.74daa4ca@notabene.brown>
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On Thu, 15 May 2014 16:11:46 +0200 Patrik Horn=C3=ADk <patrik@dsl.sk> wrote:

> Hello,
>=20
> I have couple of questions regarding data offset:
>=20
> - Current mdadm sets 128 MiB offset apparently for reshaping backup
> file. Is it really used by reshape? From which kernel / mdadm version?

Yes.  Linux 3.5 or there abouts.  mdadm 3.3
>=20
> - Is there any other good reason for such big offset?

No.  But when you typically have a terabyte of more per disc, 128MB isn't
very much.

>=20
> - Is there a support for specifying data offset when creating array?
> In which version of mdadm? What are recommended lower values?

Yes. mdadm-3.3.  Recommended value is the default.  Lowest usable value is
the lowest value it will let you use.

Why does a 128MB offset bother you?

NeilBrown

>=20
> Thanks.
>=20
> Patrik
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