From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8A9C6C4338F for ; Tue, 27 Jul 2021 23:01:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5A76E603E7 for ; Tue, 27 Jul 2021 23:01:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232650AbhG0XBR (ORCPT ); Tue, 27 Jul 2021 19:01:17 -0400 Received: from outgoing-auth-1.mit.edu ([18.9.28.11]:55837 "EHLO outgoing.mit.edu" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S232198AbhG0XBQ (ORCPT ); Tue, 27 Jul 2021 19:01:16 -0400 Received: from cwcc.thunk.org (pool-72-74-133-215.bstnma.fios.verizon.net [72.74.133.215]) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id 16RN1CAI007369 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 27 Jul 2021 19:01:13 -0400 Received: by cwcc.thunk.org (Postfix, from userid 15806) id 8DB3E15C3DBC; Tue, 27 Jul 2021 19:01:12 -0400 (EDT) Date: Tue, 27 Jul 2021 19:01:12 -0400 From: "Theodore Ts'o" To: Mikhail Morfikov Cc: linux-ext4@vger.kernel.org Subject: Re: Is it safe to use the bigalloc feature in the case of ext4 filesystem? Message-ID: References: <0dc45cbd-b3b0-97ab-66a9-f68331cb483e@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0dc45cbd-b3b0-97ab-66a9-f68331cb483e@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Fri, Jul 23, 2021 at 05:30:13PM +0200, Mikhail Morfikov wrote: > In the man ext4(5) we can read the following: > > Warning: The bigalloc feature is still under development, > and may not be fully supported with your kernel or may > have various bugs. Please see the web page > http://ext4.wiki.kernel.org/index.php/Bigalloc for details. > May clash with delayed allocation (see nodelalloc mount > option). > > According to the link above, the info is dated back to 2013, > which is a little bit ancient. > > What's the current status of the feature? Is it safe to use > bigalloc on several TiB hard disks where only big files will be > stored? Yes; the places where bigalloc is perhaps not as well tested is support FALLOC_FL_COLLAPSE_RANGE, FALLOC_FL_INSERT_RANGE, and FALLOC_FL_PUNCH_HOLE. Bigalloc is also not very efficient for large directories (where we allocate a full cluster for each directory block). Older kernels did not handle ENOSPC errors when delayed allocation was enabled, but that has since been fixed, and bigalloc is passing file system regression tests, so it should safe to use as you've described. Cheers, - Ted