From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp97.iad3a.emailsrvr.com ([173.203.187.97]:56714 "EHLO smtp97.iad3a.emailsrvr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751207AbbFPMJS convert rfc822-to-8bit (ORCPT ); Tue, 16 Jun 2015 08:09:18 -0400 Received: from smtp13.relay.iad3a.emailsrvr.com (localhost.localdomain [127.0.0.1]) by smtp13.relay.iad3a.emailsrvr.com (SMTP Server) with ESMTP id 07D951006E5 for ; Tue, 16 Jun 2015 08:09:18 -0400 (EDT) Received: from smtp13.relay.iad3a.emailsrvr.com (localhost.localdomain [127.0.0.1]) by smtp13.relay.iad3a.emailsrvr.com (SMTP Server) with ESMTP id 03BBD100608 for ; Tue, 16 Jun 2015 08:09:18 -0400 (EDT) Received: from app26.wa-webapps.iad3a (relay-webapps.rsapps.net [172.27.255.140]) by smtp13.relay.iad3a.emailsrvr.com (SMTP Server) with ESMTP id EBE221006E5 for ; Tue, 16 Jun 2015 08:09:17 -0400 (EDT) Received: from up4.tv (localhost.localdomain [127.0.0.1]) by app26.wa-webapps.iad3a (Postfix) with ESMTP id DB3DF380041 for ; Tue, 16 Jun 2015 08:09:17 -0400 (EDT) Date: Tue, 16 Jun 2015 08:09:17 -0400 (EDT) Subject: RAID10 Balancing Request for Comments and Advices From: "Vincent Olivier" To: linux-btrfs@vger.kernel.org MIME-Version: 1.0 Content-Type: text/plain;charset=UTF-8 Message-ID: <1434456557.89597618@apps.rackspace.com> Sender: linux-btrfs-owner@vger.kernel.org List-ID: Hello, I have a Centos 7 machine with the latest EPEL kernel-ml (4.0.5) with a 6-disk 4TB HGST RAID10 btrfs volume. With the following mount options : noatime,compress=zlib,space_cache 0 2 "btrfs filesystem df” gives : Data, RAID10: total=7.08TiB, used=7.02TiB Data, single: total=8.00MiB, used=0.00B System, RAID10: total=7.88MiB, used=656.00KiB System, single: total=4.00MiB, used=0.00B Metadata, RAID10: total=9.19GiB, used=7.56GiB Metadata, single: total=8.00MiB, used=0.00B GlobalReserve, single: total=512.00MiB, used=0.00B My first question is this : is it normal to have “single” blocks ? Why not only RAID10? I don’t remember the exact mkfs options I used but I certainly didn’t ask for “single” so this is unexpected. My second question is : what is the best device add / balance sequence to use if I want to add 2 more disks to this RAID10 volume? Also is a balance necessary at all since I’m adding a pair? My third question is: given that this file system is an offline backup for another RAID0 volume with SMB sharing, what is the best maintenance schedule as long as it is offline? For now, I only have a weekly cron scrub now, but I think that the priority is to have it balanced after a send-receive or rsync to optimize storage space availability (over performance). Is there a “light” balancing method recommended in this case? My fourth question, still within the same context: are there best practices when using smartctl for periodically testing (long test, short test) btrfs RAID devices? Thanks! Vincent