From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cn.fujitsu.com ([59.151.112.132]:5679 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1754140AbaDKJH0 convert rfc822-to-8bit (ORCPT ); Fri, 11 Apr 2014 05:07:26 -0400 Message-ID: <5347B10C.1080708@cn.fujitsu.com> Date: Fri, 11 Apr 2014 17:08:28 +0800 From: Qu Wenruo MIME-Version: 1.0 To: Marc MERLIN CC: Subject: Re: [PATCH 1/2] btrfs-progs: Add device management related paragraph. References: <1397184233-18535-1-git-send-email-quwenruo@cn.fujitsu.com> <20140411061048.GD7322@merlins.org> In-Reply-To: <20140411061048.GD7322@merlins.org> Content-Type: text/plain; charset="UTF-8"; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: -------- Original Message -------- Subject: Re: [PATCH 1/2] btrfs-progs: Add device management related paragraph. From: Marc MERLIN To: Qu Wenruo Date: 2014年04月11日 14:10 > 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. Sorry for my poor English, I'll try to change it to a better expression. > >> +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? That's very nice for you making a new wiki page. IMO it's OK to link to the URL. Thanks, Qu > >> +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