From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from out4-smtp.messagingengine.com ([66.111.4.28]:39022 "EHLO out4-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750749AbcBGTHC convert rfc822-to-8bit (ORCPT ); Sun, 7 Feb 2016 14:07:02 -0500 Received: from compute3.internal (compute3.nyi.internal [10.202.2.43]) by mailout.nyi.internal (Postfix) with ESMTP id 4B56820BBB for ; Sun, 7 Feb 2016 14:07:01 -0500 (EST) Received: from ebox.rath.org (ebox.rath.org [45.79.69.51]) by mail.messagingengine.com (Postfix) with ESMTPA id 0E6BE6800FA for ; Sun, 7 Feb 2016 14:07:01 -0500 (EST) Received: from vostro.rath.org (vostro [192.168.12.4]) by ebox.rath.org (Postfix) with ESMTPS id 49DE71C9E1E for ; Sun, 7 Feb 2016 19:07:00 +0000 (UTC) From: Nikolaus Rath To: linux-btrfs@vger.kernel.org Subject: Use fast device only for metadata? Date: Sun, 07 Feb 2016 11:06:58 -0800 Message-ID: <874mdktk4t.fsf@vostro.rath.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: Hello, I have a large home directory on a spinning disk that I regularly synchronize between different computers using unison. That takes ages, even though the amount of changed files is typically small. I suspect most if the time is spend walking through the file system and checking mtimes. So I was wondering if I could possibly speed-up this operation by storing all btrfs metadata on a fast, SSD drive. It seems that mkfs.btrfs allows me to put the metadata in raid1 or dup mode, and the file contents in single mode. However, I could not find a way to tell btrfs to use a device *only* for metadata. Is there a way to do that? Also, what is the difference between using "dup" and "raid1" for the metadata? Best, -Nikolaus -- GPG encrypted emails preferred. Key id: 0xD113FCAC3C4E599F Fingerprint: ED31 791B 2C5C 1613 AF38 8B8A D113 FCAC 3C4E 599F »Time flies like an arrow, fruit flies like a Banana.«