From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mykola Golub Subject: Re: rbd-nbd 2T limit Date: Fri, 10 Mar 2017 09:53:59 +0200 Message-ID: <20170310075358.GB24654@gmail.com> References: <975af97d-849e-6e65-d617-e0dc16672da4@kirneh.eu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-lf0-f67.google.com ([209.85.215.67]:35262 "EHLO mail-lf0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755062AbdCJHyI (ORCPT ); Fri, 10 Mar 2017 02:54:08 -0500 Received: by mail-lf0-f67.google.com with SMTP id v2so6247625lfi.2 for ; Thu, 09 Mar 2017 23:54:07 -0800 (PST) Content-Disposition: inline In-Reply-To: <975af97d-849e-6e65-d617-e0dc16672da4@kirneh.eu> Sender: ceph-devel-owner@vger.kernel.org List-ID: To: Henrik Korkuc Cc: Max Yehorov , ceph-devel On Thu, Mar 09, 2017 at 09:14:53AM +0200, Henrik Korkuc wrote: > On 17-03-09 05:38, Max Yehorov wrote: > >I was reading through release notes for 10.2.6 and there was a ticket > > > >rbd: rbd-nbd: disallow mapping images >2TB in size (issue#17219, > >pr#11870, Mykola Golub) > > > >default nbd block size is 1k, valid values are from 512 to PAGE_SIZE > > > >rbd_nbd.cc sets blocksize to 512 here: > >https://github.com/ceph/ceph/blob/master/src/tools/rbd_nbd/rbd-nbd.cc#L635 > > > >Why 512 was chosen for rbd_nbd? > >krbd also uses 512 sector size. Is there a reason to use 512 block > >size vs 4k AF? > I am also interested in >2TB NBD support and was disapointed when I couldn't > mount 10TB images. > > Based on issue in that commit for me it seems to be clear why it was done - > some (most?) kernels in the wild do not support larger sizes. But it looks > like support on unaffected kernels is already in master (not sure if it got > backported to current releases). For reference: > http://tracker.ceph.com/issues/17219 -> > https://github.com/ceph/ceph/pull/11741 -> > http://tracker.ceph.com/issues/18335 -> > https://github.com/ceph/ceph/pull/13229 Yes, it removes the restriction for working kernels. It is going to be backported to kraken and jewel: http://tracker.ceph.com/issues/18910 http://tracker.ceph.com/issues/18911 -- Mykola Golub