From: Andreas Dilger Subject: Re: [PATCH] ext4: Use superblock s_raid_stripe_width as stripe size during block allocation. Date: Thu, 10 Jan 2008 01:22:23 -0700 Message-ID: <20080110082223.GF3351@webber.adilger.int> References: <1199898469-10369-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <20080109233627.GB3351@webber.adilger.int> <20080110042859.GB8271@skywalker> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: cmm@us.ibm.com, tytso@mit.edu, linux-ext4@vger.kernel.org To: "Aneesh Kumar K.V" Return-path: Received: from mail.clusterfs.com ([74.0.229.162]:60651 "EHLO mail.clusterfs.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750733AbYAJIWY (ORCPT ); Thu, 10 Jan 2008 03:22:24 -0500 Content-Disposition: inline In-Reply-To: <20080110042859.GB8271@skywalker> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Jan 10, 2008 09:58 +0530, Aneesh Kumar K.V wrote: > > d) if s_stripe is still > s_blocks_per_group try s_raid_stride > > e) if s_stripe is still > s_blocks_per_group use 0 > > But i guess mke2fs and tune2fs should validate the value of > s_raid_stripe_width and s_raid_stride. Both of them should be less that > blocks per group. Should I add extra check in the kernel for them ? It's true that mke2fs and tune2fs should validate this, but it is also possible to become corrupted, and e2fsck doesn't fix it yet nor can it make a good estimate of the right value. > > > + if (!sbi->s_stripe || > > > + sbi->s_stripe >= sbi->s_blocks_per_group) { > > > > So what do you think should it be > or >=. Looking at the mballoc I > guess it should work with stripe size equal to blocks per group. I am > not sure how efficient the allocation would be though. I think if s_stripe == s_blocks_per_group that is fine... For 1kB block filesystem that is only 8MB in size. Cheers, Andreas -- Andreas Dilger Sr. Staff Engineer, Lustre Group Sun Microsystems of Canada, Inc.