From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from static.68.134.40.188.clients.your-server.de ([188.40.134.68]:46604 "EHLO mail02.iobjects.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932509AbbLWUiM (ORCPT ); Wed, 23 Dec 2015 15:38:12 -0500 Received: from tux.wizards.de (p4FF58543.dip0.t-ipconnect.de [79.245.133.67]) by mail02.iobjects.de (Postfix) with ESMTPSA id 762524160914 for ; Wed, 23 Dec 2015 21:38:10 +0100 (CET) Received: from [192.168.100.223] (ragnarok [192.168.100.223]) by tux.wizards.de (Postfix) with ESMTP id E093911C0037 for ; Wed, 23 Dec 2015 21:38:09 +0100 (CET) Subject: Re: btrfs und lvm-cache? To: linux-btrfs References: <1527885.5NheBqth0k@merkaba> <567AFF04.1030200@gmx.de> From: =?UTF-8?Q?Holger_Hoffst=c3=a4tte?= Message-ID: <567B0631.2080801@googlemail.com> Date: Wed, 23 Dec 2015 21:38:09 +0100 MIME-Version: 1.0 In-Reply-To: <567AFF04.1030200@gmx.de> Content-Type: text/plain; charset=utf-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 12/23/15 21:07, Neuer User wrote: > Understood. However, do SSDs really do automatic deduplication? I might > be completely wrong here, but that sounds to be a rather complex > mechanism, requiring lots of RAM to deduplicate 100 GB. I wouldn't have > thought that typical SSDs include that? tl;dr: no, because delta encoding/write buffer coalescing is not dedupe. This is one of those persistent myth that has been kept alive by the internet rumor machine. It has its roots in a series of blog articles [1] and turned out to be panic coupled with FUD and fueled by a lack of factual information. I suggest everyone read the article(s), ALL the comments and then get back to drinking. :o) In SSD arrays dedupe is generally seen as a good thing. -h [1] http://storagemojo.com/2011/06/27/de-dup-too-much-of-good-thing/