From mboxrd@z Thu Jan  1 00:00:00 1970
From: erik quanstrom <quanstro@quanstro.net>
Date: Fri, 30 Sep 2011 10:00:19 -0400
To: 9fans@9fans.net
Message-ID: <6c0a6fdef3589e5cb13618f19d9ac9fc@chula.quanstro.net>
In-Reply-To: <1dc3dbdc0c9e0ecbc86047c58e0a2d33@hamnavoe.com>
References: <1dc3dbdc0c9e0ecbc86047c58e0a2d33@hamnavoe.com>
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Subject: Re: [9fans] copying fossil filesystem to a bigger disk
Topicbox-Message-UUID: 2d677016-ead7-11e9-9d60-3106f5b1d025

On Fri Sep 30 04:55:43 EDT 2011, 9fans@hamnavoe.com wrote:
> > I have a WD10EARS which lies about its sector size
>
> Some further information: I'm using the sdata driver rather than
> sdiahci because my motherboard doesn't support ahci.  This may be why
> I'm seeing the disk as having 512-byte sectors not 4096.
>
> You could try telling your BIOS to use the disk in ATA (IDE) mode, and
> see if that gives you 512-byte sector emulation.  However I seem to
> recall posts from Erik advising that some chipsets have bugs in this
> mode which affect Plan 9.

to put a point on it, ata is an abstracted command set.  ide is a register
set and protocol for delivering ata commands modeled on the isa bus.

the disk interface (ide/ahci/something else) doesn't have anything to do
with the sector size.  the sector size is reported in the ident block, which
emulation layers treat as an opaque sack of bits.

there are several options in the spec (the 4k sector compatability
chapter is ~ 50 pages), so perhaps there's something to be done
about it by having the disk driver lie creatively.  unfortunately, i
don't have one of these disks.

the long-term solution is to fix mbr and fdisk to play nicely with
4096-byte sectors.  (if you want to do this yourself, you can use the
sdloop driver.  it will use whatever sector size you give it.)

if you (slash) could just grab the atazz binary (ftp://ftp.quanstro.net/other/8.atazz)
and send me the output of
	echo 'identify device' | 8.atazz -r >[2=] /dev/sdE0 > /tmp/somefile
that would be great.  thanks!

- erik