Message-Id: <200106281354.f5SDsmp15488@jen.americas.sgi.com>
To: "Holger Smolinski" <HSmolinski@de.ibm.com>
cc: linux-xfs@oss.sgi.com
Subject: Re: Contraint to Blksize 512? 
References: <OF4755C299.0CF3FF75-ONC1256A79.0041C241@de.ibm.com>
Comments: In-reply-to "Holger Smolinski" <HSmolinski@de.ibm.com>
   message dated "Thu, 28 Jun 2001 15:37:01 +0200."
Date: Thu, 28 Jun 2001 08:54:48 -0500
From: Steve Lord <lord@sgi.com>
Sender: owner-linux-xfs@oss.sgi.com
Precedence: bulk

> Hello,
> I tried to use XFS with devices of sector sizes larger than 512 Byte and
> failed.
> Apparently there are dependencies to a fixed blocksize of 512 Byte all over
> the code of XFS.
> Are these contraints unavoidable by the design of XFS or could you imagine
> running an XFS e.g. on a device with 4k blocksize and what needs to be done
> to the code in order to do so?
> 
> Gruesse / Regards
>         Dr. Holger Smolinski

Yes, unfortunately XFS is built around assumptions about 512 byte block
sizes. There was an internal project to clean this up which was shelved
a while back, I will ask around and see if the code still exists. I
think this would end up with an incompatible on disk format, given that
some structures would change size, but I think that would be an acceptable
solution for devices with a larger block size.

I mentioned one of the aspects in email yesterday, there are some 512
byte long metadata objects which need to be separately accessible on
disk. The one I forgot is the log, which is written in 512 byte chunks.

Steve