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 27B08C433F5 for ; Wed, 9 Mar 2022 02:40:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231493AbiCIClF (ORCPT ); Tue, 8 Mar 2022 21:41:05 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54098 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231426AbiCIClE (ORCPT ); Tue, 8 Mar 2022 21:41:04 -0500 X-Greylist: delayed 4199 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Tue, 08 Mar 2022 18:40:05 PST Received: from rin.romanrm.net (rin.romanrm.net [51.158.148.128]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 661763B2B1 for ; Tue, 8 Mar 2022 18:40:03 -0800 (PST) Received: from nvm (nvm2.home.romanrm.net [IPv6:fd39::4a:3cff:fe57:d6b5]) by rin.romanrm.net (Postfix) with SMTP id AD3AF6CF; Tue, 8 Mar 2022 23:34:48 +0000 (UTC) Date: Wed, 9 Mar 2022 04:34:47 +0500 From: Roman Mamedov To: Jani Partanen Cc: David T-G , Linux RAID Subject: Re: striping 2x500G to mirror 1x1T Message-ID: <20220309043447.70281a4d@nvm> In-Reply-To: <9b00eff9-1540-228c-60af-d33c32e1b45a@sotapeli.fi> References: <20220305044704.GB4455@justpickone.org> <9b00eff9-1540-228c-60af-d33c32e1b45a@sotapeli.fi> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-raid@vger.kernel.org On Wed, 9 Mar 2022 01:08:47 +0200 Jani Partanen wrote: > Hello, I don't think you gain really any benefit from that raid-0, just > go linear array, IMHO. There is no gain from the linear array either. In none of the performance, reliability or even simplicity, since managing a linear md array is not any simpler than managing an md RAID0. Smaller disks tend to be slower in linear speeds than larger and more densely written ones. If that is the case with the particular models used here, then having the 2x500 side in a RAID0 will help them match up in linear speeds to the 1TB side. And a very good point that Wols mentioned, the 1TB-disk member can be set as --write-mostly, since the 2x500GB RAID0 is likely to overshoot the performance of a single 1TB disk, even if its individual disks were slower. Not to mention it has two independent head sets for the same amount of data. (If we're still talking rotational here...) -- With respect, Roman