From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay4-d.mail.gandi.net ([217.70.183.196]:60979 "EHLO relay4-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756602AbaDKJm1 convert rfc822-to-8bit (ORCPT ); Fri, 11 Apr 2014 05:42:27 -0400 Received: from mfilter26-d.gandi.net (mfilter26-d.gandi.net [217.70.178.154]) by relay4-d.mail.gandi.net (Postfix) with ESMTP id 3549117208C for ; Fri, 11 Apr 2014 11:42:26 +0200 (CEST) Received: from relay4-d.mail.gandi.net ([217.70.183.196]) by mfilter26-d.gandi.net (mfilter26-d.gandi.net [10.0.15.180]) (amavisd-new, port 10024) with ESMTP id aFF6jbe+6dG2 for ; Fri, 11 Apr 2014 11:42:24 +0200 (CEST) Received: from zafu.localnet (dhcp230.cr2i.univ-montp2.fr [162.38.105.230]) (Authenticated sender: michel@bouissou.net) by relay4-d.mail.gandi.net (Postfix) with ESMTPSA id 74C12172097 for ; Fri, 11 Apr 2014 11:42:24 +0200 (CEST) From: =?ISO-8859-1?Q?Sw=E2mi?= Petaramesh To: linux-btrfs@vger.kernel.org Subject: How to make BTRFS crawl Date: Fri, 11 Apr 2014 11:42:23 +0200 Message-ID: <4171851.75rN5oGIof@zafu> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Sender: linux-btrfs-owner@vger.kernel.org List-ID: Hi, I was asked about situations "use cases" that would cause BTRFS to slow down to a crawl. And it's exactly what happened to me yesterday when I was trying, on the contrary, to speed it up. So here's the recipe for getting a "slow to the point it is unusable" BTRFS. 1/ Perform a clean, fresh install of a recent distro with a 3.13 kernel (i.e. Fedora 20) and a BTRFS root filesystem. 2/ Choose the version with a KDE interface 3/ Configure fstab mountpoints using such options (space_cache will have been manually activated once): / btrfs subvol=FEDORA,noatime,compress=lzo,autodefrag /home btrfs subvol=HOME,noatime,compress=lzo,autodefrag 4/ Use "chattr +C" to make the following directories NOCOW (move the old directory elsewhere, create a new dir, make it nocow, copy files from the old one so they are recreated with nocow, check permissions...): - /home/yourself/.cache - /home/yourself/.local/share/akonadi 5/ Use IMAP mail in Kmail. Seriously process your email (it will be stored using akonadi mysql) 6/ Surf normally the web using Firefox 7/ Install SuSE "snapper" package that will perform a FS snapshot every hour. Configure it so it will snapshot both the root FS subvol and the /home subvol 8/ Use the system for 24 hours and you will know that "hardly usable" means... Especially every hour-on-the-hour when Kmail or Firefox will try to access files that have been recently snapshotted... Your system will be dead with saturated HD access for several *minutes* ...Hope this may help hunting this down... Kind regards. -- Swâmi Petaramesh http://petaramesh.org PGP 9076E32E