From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from magic.merlins.org ([209.81.13.136]:57448 "EHLO mail1.merlins.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754945AbaDKGKs (ORCPT ); Fri, 11 Apr 2014 02:10:48 -0400 Date: Thu, 10 Apr 2014 23:10:48 -0700 From: Marc MERLIN To: Qu Wenruo Cc: linux-btrfs@vger.kernel.org Subject: Re: [PATCH 1/2] btrfs-progs: Add device management related paragraph. Message-ID: <20140411061048.GD7322@merlins.org> References: <1397184233-18535-1-git-send-email-quwenruo@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1397184233-18535-1-git-send-email-quwenruo@cn.fujitsu.com> Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Fri, Apr 11, 2014 at 10:43:52AM +0800, Qu Wenruo wrote: > Add device management related paragraph to better explain btrfs device > management. Thank you for these updates. > Cc: Marc MERLIN > Signed-off-by: Qu Wenruo (comments below) > --- > Documentation/btrfs-balance.txt | 3 +++ > Documentation/btrfs-device.txt | 42 +++++++++++++++++++++++++++++++++++++++++ > Documentation/btrfs-replace.txt | 4 ++++ > 3 files changed, 49 insertions(+) > > diff --git a/Documentation/btrfs-balance.txt b/Documentation/btrfs-balance.txt > index 2289fdf..1b1861c 100644 > --- a/Documentation/btrfs-balance.txt > +++ b/Documentation/btrfs-balance.txt > @@ -14,6 +14,8 @@ DESCRIPTION > 'btrfs balance' is used to balance chunks in a btrfs filesystem across > multiple or even single device. > > +See `btrfs-device`(8) for more details about the effect on device management. > + > SUBCOMMAND > ---------- > :: > @@ -75,3 +77,4 @@ further details. > SEE ALSO > -------- > `mkfs.btrfs`(8), > +`btrfs-device`(8) > diff --git a/Documentation/btrfs-device.txt b/Documentation/btrfs-device.txt > index 20d7bcd..474d411 100644 > --- a/Documentation/btrfs-device.txt > +++ b/Documentation/btrfs-device.txt > @@ -14,6 +14,46 @@ DESCRIPTION > 'btrfs device' is used to control the btrfs devices, since btrfs can be used > across several devices, 'btrfs device' is used for multiple device management. > > +DEVICE MANAGEMENT > +----------------- > +Btrfs filesystem is capable to manage multiple devices. > + > +Btrfs filesystem use different profiles to manage different RAID level, and > +use balance to rebuild chunks, also devices can be added/removed/replace > +online. > + > +Profile:: > +Btrfs filesystem use data/metadata profiles to manage allocation/duplication > +mechanism. Profiles like RAID level can be assigned to data and metadata separately. > ++ > +See `mkfs.btrfs`(8) for more details. > + > +RAID level:: > +Btrfs filesystem supports most of the standard RAID level: 0/1/5/6/10. > +RAID levels can be assigned at mkfs time or online. > ++ > +See `mkfs.btrfs`(8) for mkfs time RAID level assign and `btrfs-balance`(8) for > +online RAID level assign. > + > +Balance:: > +`btrfs-balance`(8) subcommand can be used to balance or rebuild chunks to the > +desired profile. > ++ > +Due to the fact that balance can rebuild/recovery chunks according to its RAID > +duplication if possible, so when using RAID1/5/6/10 with some devices failed > +and you just added a new device to btrfs using `btrfs-device`(8), you should > +run `btrfs-balance`(8) to rebuild the chunks. > ++ > +See `btrfs-balance`(8) for more details. > + > +Device add/remove/replace:: > +Device can be added/removed using `btrfs-replace`(8) subcommand and replaced > +using `btrfs-replace`(8). I'm not sure I understand this sentence exactly. > +When device is removed or replaced, btrfs will do the chunk rebuild if needed. > ++ > +See `btrfs-replace`(8) and this man page for more details. > + > SUBCOMMAND > ---------- > 'add' [-Kf] [...] :: > @@ -73,3 +113,5 @@ further details. > SEE ALSO > -------- > `mkfs.btrfs`(8), > +`btrfs-replace`(8), > +`btrfs-balance`(8) > diff --git a/Documentation/btrfs-replace.txt b/Documentation/btrfs-replace.txt > index 8c5dcc4..15a46c2 100644 > --- a/Documentation/btrfs-replace.txt > +++ b/Documentation/btrfs-replace.txt > @@ -13,6 +13,9 @@ DESCRIPTION > ----------- > 'btrfs replace' is used to replace btrfs managed devices with other device. I would add a quick line here saying that it's not currently supported for RAID5/6, and to see btrfs-device for add/delete to get around the replace missing problem. I've explained that in more details on https://btrfs.wiki.kernel.org/index.php/FAQ#Can_I_use_RAID.5B56.5D_on_my_Btrfs_filesystem.3F but it may not be a great page to link to. Ok, I just made a new nice page for you: https://btrfs.wiki.kernel.org/index.php/RAID56 Do you think it would be ok to link to https://btrfs.wiki.kernel.org/index.php/RAID56#Parity_Rebuilds_and_Advanced_Disk_Replacement in the btrfs replace man page? > +It is recommended to see `btrfs-device`(8) for more details about btrfs device > +management. > + > SUBCOMMAND > ---------- > 'start' [-Bfr] | :: > @@ -74,3 +77,4 @@ further details. > SEE ALSO > -------- > `mkfs.btrfs`(8), > +`btrfs-device`(8), > -- > 1.9.2 The rest looks good. Thank you, Marc -- "A mouse is a device used to point at the xterm you want to type in" - A.S.R. Microsoft is to operating systems .... .... what McDonalds is to gourmet cooking Home page: http://marc.merlins.org/