Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751119AbWCaGmN (ORCPT ); Fri, 31 Mar 2006 01:42:13 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751133AbWCaGmN (ORCPT ); Fri, 31 Mar 2006 01:42:13 -0500 Received: from mail.clusterfs.com ([206.168.112.78]:34754 "EHLO mail.clusterfs.com") by vger.kernel.org with ESMTP id S1751119AbWCaGmM (ORCPT ); Fri, 31 Mar 2006 01:42:12 -0500 Date: Thu, 30 Mar 2006 23:42:09 -0700 From: Andreas Dilger To: Mingming Cao Cc: Andrew Morton , Takashi Sato , Laurent Vivier , linux-kernel@vger.kernel.org, ext2-devel , linux-fsdevel@vger.kernel.org Subject: Re: [RFC][PATCH 0/2]Extend ext3 filesystem limit from 8TB to 16TB Message-ID: <20060331064209.GH17364@schatzie.adilger.int> Mail-Followup-To: Mingming Cao , Andrew Morton , Takashi Sato , Laurent Vivier , linux-kernel@vger.kernel.org, ext2-devel , linux-fsdevel@vger.kernel.org References: <1143485147.3970.23.camel@dyn9047017067.beaverton.ibm.com> <20060327131049.2c6a5413.akpm@osdl.org> <20060327225847.GC3756@localhost.localdomain> <1143530126.11560.6.camel@openx2.frec.bull.fr> <1143568905.3935.13.camel@dyn9047017067.beaverton.ibm.com> <1143623605.5046.11.camel@openx2.frec.bull.fr> <1143682730.4045.145.camel@dyn9047017067.beaverton.ibm.com> <20060330174008.GW5030@schatzie.adilger.int> <1143746202.3896.32.camel@dyn9047017067.beaverton.ibm.com> <1143746561.3896.35.camel@dyn9047017067.beaverton.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1143746561.3896.35.camel@dyn9047017067.beaverton.ibm.com> User-Agent: Mutt/1.4.1i X-GPG-Key: 1024D/0D35BED6 X-GPG-Fingerprint: 7A37 5D79 BF1B CECA D44F 8A29 A488 39F5 0D35 BED6 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1449 Lines: 34 On Mar 30, 2006 11:22 -0800, Mingming Cao wrote: > I made a kernel patch to allow a file to specify which block group it > wants it's blocks to allocate from(using ioctl to set the goal > allocation block group). I set the goal block group falls to somewhere > >8TB, and did dd tests on that file. Verified this with debugfs, the > allocated block numbers are beyond 2**31. > > Also before run fsx tests, created many directories (32768 at most:) and > verified one directory's inode is located in block group >8TB space. So > when we do fsx test on files under that directory, we are > creating/testing files >8TB. While useful, I don't think it is critical. As you mention, it is possible to do this by creating a lot of directories, though it might be tedious (need over 16k directories for a 2TB filesystem, 64k for an 8TB fs). Also, since this increases the allocation for each inode's reservation from 16 bytes to 20 (really 32 because it is in a slab), it might have a small performance hit. If it was available under some sort of compile-time configuration option it might make sense for developers. Cheers, Andreas -- Andreas Dilger Principal Software Engineer Cluster File Systems, Inc. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/