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=-7.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 54317C433E0 for ; Mon, 18 Jan 2021 00:49:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1C69B20758 for ; Mon, 18 Jan 2021 00:49:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728741AbhARAtM (ORCPT ); Sun, 17 Jan 2021 19:49:12 -0500 Received: from fbo-4.mxes.net ([198.205.123.79]:13278 "EHLO fbo-4.mxes.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726785AbhARAtJ (ORCPT ); Sun, 17 Jan 2021 19:49:09 -0500 X-Greylist: delayed 583 seconds by postgrey-1.27 at vger.kernel.org; Sun, 17 Jan 2021 19:49:08 EST Received: from smtp-out-3.mxes.net (smtp-out-3.mxes.net [IPv6:2605:d100:2f:10::314]) by fbi-4.mxes.net (Postfix) with ESMTP id 04FC275990 for ; Sun, 17 Jan 2021 19:39:31 -0500 (EST) Received: from Customer-MUA (mua.mxes.net [10.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by smtp.mxes.net (Postfix) with ESMTPSA id E212675A14; Sun, 17 Jan 2021 19:38:30 -0500 (EST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mxes.net; s=mta; t=1610930316; bh=UjwC2zsfcDqa0mib3MV1H0nhlwTVKH7k7DUctXw3XRE=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=AvkyyypYS27WOAwzl0Mv++7Cyw9M18elxIIVhh3QshGg/aHUZQCJnmnPGzjV0TXom 1xHMt7ciy4pdLWe5zB9YwgXiQzUtuu5OvDonGuH09wYLyftoNhGK3Os4Gpa8FebhFX Z7cIDJ57t+5MGynYyH9+4nyFnPk2vdiMxdV3Mv3Q= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=siru.org; s=default; t=1610930316; bh=UjwC2zsfcDqa0mib3MV1H0nhlwTVKH7k7DUctXw3XRE=; l=1620; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=olwKGE/4sSoANcJEv7n39CQZNwr17V5JrSriK9RRrCPhcg/VS49Fflukhm5/cmWnS PkvKHzoJTPkVi5ATB1ZEVavbNuXqBASFWrRk1GYqRo24kj26cm3n+OVwKUEvRDdeBE Vwl56F+z9yosbM8UC0n1oTRUozqWMkkh8a8lr1O8= Subject: Fast, SLC SAS SSD's as dm-cache or bcache [Re: NVME experience?] To: Zygo Blaxell , Graham Cobb Cc: linux-btrfs@vger.kernel.org References: <20210117195516.GK31381@hungrycats.org> From: Andrew Luke Nesbit Message-ID: <7cae8893-aa56-7399-f0f0-742547c9780d@siru.org> Date: Mon, 18 Jan 2021 00:38:28 +0000 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:78.0) Gecko/20100101 Thunderbird/78.6.1 MIME-Version: 1.0 In-Reply-To: <20210117195516.GK31381@hungrycats.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit X-Sent-To: Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org Dear Zygo, Thank you for this fantastic message. I hope you -- and the rest of the list -- doesn't mind my jumping in mid-message... On 17/01/2021 19:55, Zygo Blaxell wrote: > You can use a NVME device as a dm-cache or bcache device--the low-latency > interface is ideal for caching use cases, if you have a suitably fast > and robust SSD. I have about 4 enterprise grade HGST SLC 100 GB and SLC 200 GB SAS SSD's. I want to use these as some kind of cache or fast tier for a NAS I am building. **It has been suggested to me that I should use these SLC SAS drives with dm-cache, by pairing one of each of four SSD's with a corresponding high capacity NAS drive.** This is for a home NAS so quietness is the major concern. Putting the NAS in our living room is the only practical option _at this point in time_ for various reasons. This is going to be a "pure NAS" and the chassis will be roomy. For example, I already have both the following chassis and I have yet to choose one or the other: - Supermicro SC 732D4F-903B ( https://www.supermicro.com/en/products/chassis/tower/732/SC732D4F-903B ) - Fractal Define XL R2 ( https://www.fractal-design.com/products/cases/define/define-xl-r2/black-pearl/ ) I think WD Red or Seagate Ironwolf drives would be best option as they run at 5400 RPM and keep vibration lower. 4x 8-14 TB HDD's in mirrored pairs (obvioulsy taken the dm-cache pair also into account). Note to self: Investigate HDD mounting kits to absorb mechanical vibration. Recommendations are welcome! Any other suggestions would be greatly welcome!! Andrew