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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F2029C433FE for ; Sun, 9 Oct 2022 11:52:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229938AbiJILwF (ORCPT ); Sun, 9 Oct 2022 07:52:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41932 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229657AbiJILwE (ORCPT ); Sun, 9 Oct 2022 07:52:04 -0400 X-Greylist: delayed 589 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Sun, 09 Oct 2022 04:52:02 PDT Received: from len.romanrm.net (len.romanrm.net [IPv6:2001:41d0:1:8b3b::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3BD302C10B for ; Sun, 9 Oct 2022 04:52:01 -0700 (PDT) Received: from nvm (nvm2.home.romanrm.net [IPv6:fd39::4a:3cff:fe57:d6b5]) by len.romanrm.net (Postfix) with SMTP id 96AC640118; Sun, 9 Oct 2022 11:42:06 +0000 (UTC) Date: Sun, 9 Oct 2022 16:42:06 +0500 From: Roman Mamedov To: Ochi Cc: linux-btrfs@vger.kernel.org Subject: Re: RAID5 on SSDs - looking for advice Message-ID: <20221009164206.39de4305@nvm> In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Sun, 9 Oct 2022 12:34:57 +0200 Ochi wrote: > 3. Are there any other known issues that come to mind regarding this > particular setup, or do you have any other advice? Keep in mind that Btrfs RAID5/6 are not currently recommended for use: https://btrfs.readthedocs.io/en/latest/btrfs-man5.html#raid56-status-and-recommended-practices If the NAS is backed up anyway, I suggest going with directory-level merge of filesystems, such as MergerFS. If one SSD fails, you will need to restore only the files which happened to be on that one, not redo the entire thing, as would be the case with RAID0, Btrfs single profile, or LVM-based large block device across all three. Another alternative is mdadm RAID5 with Btrfs on top. But it feels like that also has its own corner cases when it comes to sudden power losses, which may result in the "parent transid failed" condition from Btrfs-side (not sure if the recent PPL in mdadm fixes that). -- With respect, Roman