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SubjectRe: confused about raw-io blocksizes
On Fri, 9 Nov 2001, Andreas Dilger wrote:

> On Nov 10, 2001 00:52 +0100, Terje Eggestad wrote:
> > I'm curious as to what sets the smallest legal blocksize for raw-io, I
> > get different values for different partitions on the same disk drive.
> >
> > In all my tests I've used
> > raw /dev/raw/raw2 <block speclial file>
> > and to test block size:
> > dd if=/dev/raw/raw2 of=/dev/null bs=N count=1
> > where N is either 512, 1024, or 4096.
> > (I've a RH7.1 with a dd that do propper buffer alignment)
> > Failure is always "invalid argument" which singify either misaligned
> > buffer or illegal read length.
> >
> > What confuses me is that when raw2 is bound to /dev/hda bs=512 is ok.
> > However when binding raw2 to the different partitions on /dev/hda, some
> > are ok with 512, some will only accept 1024, and one required 4096.
>
> It may be getting confused with the filesystem blocksize. Check tune2fs -l
> for those devices.
>
> > When creating an lvm vg on one partition (/dev/hda6), and I've created
> > two logical volumes on it, one was ok with 1024 and the other required
> > 4096. When binding a raw to /dev/hda6 dd with bs=512 was ok.
>
> LVM is broken in this regard, unless you have a recent patch (Linus'
> kernel does not). I sent him a patch to fix that, but it did not get in.

I'm been trying with RH 2.4.2-2, stock 2.4.10, stock 2.4.13, and a RH
2.4.3 with some additional patches. All of them has lvm 0.9.1_beta2
(isn't that getting old??)

That patch of ours may fix my problem, could you forward it to me please?
Is it included in later lvm versin from sistna?
I really want to be using lvm for the oracle partitions.

>
> What kernel version/LVM do you have? Are you using LVM on all of these
> partitions, or only some? Did you have filesystems on them?
>

The two disk I've used for exploration is:
/dev/hda1 * 1 500 4016218+ 83 Linux
/dev/hda2 501 935 3494137+ 5 Extended
/dev/hda5 501 564 514048+ 82 Linux swap
/dev/hda6 565 935 2980026 8e Linux LVM

hda bs=512, hda1 bs=4096, hda2 bs=512, hda5 bs=512, hda6 bs=512


/dev/hda1 1 102 51376+ 83 Linux
/dev/hda2 103 20928 10496304 5 Extended
/dev/hda5 103 12293 6144232+ 83 Linux
/dev/hda6 12294 12903 307408+ 82 Linux swap
/dev/hda7 12904 20928 4044568+ 83 Linux

hda bs=512, hda1 bs=1024, hda2 bs=512, hda5 bs=1024, hda6 bs=512,
hda7 bs=1024

Looks like your absolutly right about the fs, they're the only one
causing trouble.

The lvm volumes was zero out by dd if=/dev/zero of=loc.block.spec.file
the only reason I started with disk partitions was to try to figure out
what was going on.


Thx
TJ

> Cheers, Andreas
> --
> Andreas Dilger
> http://sourceforge.net/projects/ext2resize/
> http://www-mddsp.enel.ucalgary.ca/People/adilger/
>
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--
_________________________________________________________________________

Terje Eggestad terje.eggestad@scali.no
Scali Scalable Linux Systems http://www.scali.com

Olaf Helsets Vei 6 tel: +47 22 62 89 61 (OFFICE)
P.O.Box 70 Bogerud +47 975 31 574 (MOBILE)
N-0621 Oslo fax: +47 22 62 89 51
NORWAY
_________________________________________________________________________

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