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From: Chris Mason <chris.mason@oracle.com>
To: Jan Engelhardt <jengelh@computergmbh.de>
Cc: David Miller <davem@davemloft.net>,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	btrfs-devel@oss.oracle.com
Subject: Re: BTRFS partition usage...
Date: Tue, 12 Feb 2008 09:08:59 -0500	[thread overview]
Message-ID: <200802120908.59602.chris.mason@oracle.com> (raw)
In-Reply-To: <Pine.LNX.4.64.0802121458420.21102@fbirervta.pbzchgretzou.qr>

On Tuesday 12 February 2008, Jan Engelhardt wrote:
> On Feb 12 2008 08:49, Chris Mason wrote:
> >> > This is a real issue on sparc where the default sun disk labels
> >> > created use an initial partition where block zero aliases the disk
> >> > label.  It took me a few iterations before I figured out why every
> >> > btrfs make would zero out my disk label :-/
> >>
> >> Actually it seems this is only a problem with mkfs.btrfs, it clears
> >> out the first 64 4K chunks of the disk for whatever reason.
> >
> >It is a good idea to remove supers from other filesystems.  I also need to
> > add zeroing at the end of the device as well.
> >
> >Looks like I misread the e2fs zeroing code.  It zeros the whole external
> > log device, and I assumed it also zero'd out the start of the main FS.
> >
> >So, if Btrfs starts zeroing at 1k, will that be acceptable for you?
>
> Something looks wrong here. Why would btrfs need to zero at all?
> Superblock at 0, and done. Just like xfs.
> (Yes, I had xfs on sparc before, so it's not like you NEED the
> whitespace at the start of a partition.)

I've had requests to move the super down to 64k to make room for bootloaders, 
which may not matter for sparc, but I don't really plan on different 
locations for different arches.

4k aligned is important given that sector sizes are growing.

-chris

  reply	other threads:[~2008-02-12 14:10 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-06 17:00 [ANNOUNCE] Btrfs v0.12 released Chris Mason
2008-02-11  1:12 ` David Miller
2008-02-11 13:42   ` Chris Mason
2008-02-12  6:43     ` David Miller
2008-02-12 13:43       ` Chris Mason
2008-02-12  7:21 ` BTRFS partition usage David Miller
2008-02-12  8:11   ` David Miller
2008-02-12 13:49     ` Chris Mason
2008-02-12 14:00       ` Jan Engelhardt
2008-02-12 14:08         ` Chris Mason [this message]
2008-02-12 14:21           ` Jan Engelhardt
2008-02-12 14:35             ` Chris Mason
2008-02-12 15:04               ` Jan Engelhardt
2008-02-12 16:17                 ` Chris Mason
2008-02-12 23:38                 ` David Miller
2008-02-12 23:42                   ` Jan Engelhardt
2008-02-13  1:09                     ` David Miller
2008-02-13  1:22                     ` Rene Herman
2008-02-12 23:35               ` David Miller
2008-02-13  7:02                 ` Christoph Hellwig
2008-02-12 23:34             ` David Miller
2008-02-12 23:33           ` David Miller
2008-02-13  2:10             ` Jeff Garzik
2008-02-14  0:51               ` Szabolcs Szakacsits
2008-02-12 23:26         ` David Miller
2008-02-12 23:39           ` Jan Engelhardt
2008-02-13  1:08             ` David Miller
2008-02-13  1:25           ` Bryan Henderson
2008-02-12 23:28         ` David Miller
2008-02-13  0:45           ` Theodore Tso
2008-02-12 20:50       ` David Miller
2008-02-12  9:23 ` CRC32C big endian bugs David Miller
2008-02-12 21:55 ` BTRFS only works with PAGE_SIZE <= 4K David Miller
2008-02-12 22:03   ` Chris Mason

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