From: Andreas Dilger Subject: Re: [RFC][PATCH 1/11][take 2] add new mkfs option to create ext4 filesystems Date: Mon, 25 Jun 2007 15:59:23 -0600 Message-ID: <20070625215922.GM5181@schatzie.adilger.int> References: <467A936F.7030502@bull.net> <467FD71A.7030003@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Valerie Clement , Theodore Tso , ext4 development To: "Aneesh Kumar K.V" Return-path: Received: from mail.clusterfs.com ([206.168.112.78]:43639 "EHLO mail.clusterfs.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752607AbXFYV70 (ORCPT ); Mon, 25 Jun 2007 17:59:26 -0400 Content-Disposition: inline In-Reply-To: <467FD71A.7030003@linux.vnet.ibm.com> Sender: linux-ext4-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Jun 25, 2007 20:24 +0530, Aneesh Kumar K.V wrote: > Why would one need variable descriptor size. Right now we have only two > descriptor sizes right (32 and 64 ). Can't we figure out > the descriptor size we should use by looking at the partition size ? What > is that i am missing ?. Because one may want to expand an ext4 filesystem over 16TB after format time, and this would require a 64-byte descriptor. In ext4 the descriptor is almost completely full already (to deal with BIG_BG changes, and possibly large blocksize changes), so we may even need 128-byte descriptors soon. Cheers, Andreas -- Andreas Dilger Principal Software Engineer Cluster File Systems, Inc.