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 98054C433E0 for ; Wed, 17 Feb 2021 10:19:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6235764EB3 for ; Wed, 17 Feb 2021 10:19:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232297AbhBQKS6 (ORCPT ); Wed, 17 Feb 2021 05:18:58 -0500 Received: from rin.romanrm.net ([51.158.148.128]:54648 "EHLO rin.romanrm.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232251AbhBQKSp (ORCPT ); Wed, 17 Feb 2021 05:18:45 -0500 Received: from natsu (unknown [IPv6:fd39::e99e:8f1b:cfc9:ccb8]) by rin.romanrm.net (Postfix) with SMTP id 2D982870; Wed, 17 Feb 2021 10:17:59 +0000 (UTC) Date: Wed, 17 Feb 2021 15:17:59 +0500 From: Roman Mamedov To: pg@mdraid.list.sabi.co.UK (Peter Grandi) Cc: list Linux RAID Subject: Re: use ssd as write-journal or lvm-cache? Message-ID: <20210217151759.60abe249@natsu> In-Reply-To: <24620.55192.588729.189939@cyme.ty.sabi.co.uk> References: <20210217110923.62fd685f@natsu> <24620.55192.588729.189939@cyme.ty.sabi.co.uk> 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, 17 Feb 2021 09:45:12 +0100 pg@mdraid.list.sabi.co.UK (Peter Grandi) wrote: > The main point of "enterprise" flash SSD models is (as the > original poster wrote) the ability to enable write-back (thus > much, much higher committed write rates), if they have > persistent buffering. I read the OP as they meant enabling the write-back mode of LVM cache, where loss of the SSD may lead to a data loss for the entire array, and justifying that simply by the SSD being a reliable datacenter one. My objection was to that, but perhaps indeed I understood that part wrong. -- With respect, Roman