-------- Original Message --------
Subject: Re: [PATCH 1/2] btrfs-progs: Add device management related
paragraph.
From: Marc MERLIN <marc@xxxxxxxxxxx>
To: Qu Wenruo <quwenruo@xxxxxxxxxxxxxx>
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 <marc@xxxxxxxxxxx>
Signed-off-by: Qu Wenruo <quwenruo@xxxxxxxxxxxxxx>
(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
----------
<path>::
@@ -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] <dev> [<dev>...] <path>::
@@ -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] <srcdev>|<devid> <targetdev> <path>::
@@ -74,3 +77,4 @@ further details.
SEE ALSO
--------
`mkfs.btrfs`(8),
+`btrfs-device`(8),
--
1.9.2
The rest looks good.
Thank you,
Marc
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