From: Theodore Tso Subject: Re: #blocks per group too big: 37265 Date: Thu, 3 Apr 2008 14:39:29 -0400 Message-ID: <20080403183929.GE13486@mit.edu> References: <20080403161904.GA31670@msgid.wurtel.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii To: linux-ext4@vger.kernel.org Return-path: Received: from BISCAYNE-ONE-STATION.MIT.EDU ([18.7.7.80]:35605 "EHLO biscayne-one-station.mit.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755530AbYDCSjk (ORCPT ); Thu, 3 Apr 2008 14:39:40 -0400 Content-Disposition: inline In-Reply-To: <20080403161904.GA31670@msgid.wurtel.net> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Thu, Apr 03, 2008 at 06:19:04PM +0200, Paul Slootman wrote: > Hi, > I wanted to try out ext4 on my shiny new 9+TB RAID5 device > (11 x 1TB disks in md raid5). > > I obtained the 1.39-tyt3 version of e2fsprogs, and did: > > ./mkfs.ext3 -j -m 0 -N 1000000000 -O dir_index,filetype,resize_inode -E stride=65536,resize=5120000000 -J device=/dev/mapper/vg11-md15--journal -L data2 /dev/md15 > > (If using a separate device for the journal is inadvisable, please let > me know; this is on a different set of spindles that md15 is running on.) > > The stride was calculated from the 64k chunk of the raid5 device. > Mainly a guess, as I couldn't find any clear reference on how to plug in > the values to fill this in. The stride parameter is the problem. Newer versions of e2fsprogs don't allow a stride parameter which is too big. If you want to do the perfect calculation, you take the 64k chunk size, and divide it by the 4k blocksize to yield a stride parameter of 16. Actually, though, simply using a non-zero stride size is actually good enough --- and if you have a even number of RAID-5 disks, you might not need this parameter at all. (It's only purpose is to perturb the location of the block bitmaps so that all of the bitmaps don't end up on a single hard drive.) BTW, we will be making a new snapshot for people who want to test ext4 soon.... - Ted