From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mr001msb.fastweb.it ([85.18.95.85]:47131 "EHLO mr001msb.fastweb.it" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751273AbdIPT7c (ORCPT ); Sat, 16 Sep 2017 15:59:32 -0400 Subject: Re: XFS and sector size on thin volumes MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Sat, 16 Sep 2017 21:59:27 +0200 From: Gionatan Danti In-Reply-To: <4ca74023-dcaf-9963-1b8f-2c1924866564@sandeen.net> References: <20170909231215.GK17782@dastard> <0c59ba403f83e571d695a716ccad5d0a@assyoma.it> <20170909235323.GL17782@dastard> <838841738c3d8ca84328075615f95475@assyoma.it> <9d6b72e9-37ca-70f9-a40d-62ceaafc9db6@sandeen.net> <1357a2ee8280242c68d92cd4aba06f51@assyoma.it> <4ca74023-dcaf-9963-1b8f-2c1924866564@sandeen.net> Message-ID: <58a80905e97216e37d72e5b7bd9f1643@assyoma.it> Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: Eric Sandeen Cc: Dave Chinner , linux-xfs@vger.kernel.org, g.danti@assyoma.it Il 16-09-2017 20:33 Eric Sandeen ha scritto: > > I don't think I said that - this is the first time you've mentioned > /alignment/, and I've seen no indication of your alignment one way or > another. > > > > > that specifies a 4k block size, which is already the default. > > You're conflating a lot of issues here - log alignment, sector size, > physical & logical block size presented by both the underlying > storage and the zvol ... > > I cannot speak to zvols, as I have no experience with them. > > But if the underlying storage is 512e/4k then you may want to specify > the 4k /sector/ size with -s size=4k. > > -Eric > Hi Eric, you are right: I messed up the terminology. Sorry for the noise. I was really speaking about *sector* size. In short, when using ZVOL the physical disk's sector size is not directly announced to the higher layer filesystem. This, in turn, cause mkfs.xfs to automatically select a 512B sector size, even when running on top of 512e/4Kn disks. From previous emails/threads, I was under impression that XFS sector size only very marginally affect performance. It that true? Can I stick with default mkfs settings? Or should I manually select 4K sector size ("-s size=4k")? Thanks. -- Danti Gionatan Supporto Tecnico Assyoma S.r.l. - www.assyoma.it email: g.danti@assyoma.it - info@assyoma.it GPG public key ID: FF5F32A8