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authorArtur Paszkiewicz <artur.paszkiewicz@intel.com>2017-03-09 12:00:00 +0300
committerShaohua Li <shli@fb.com>2017-03-17 02:55:55 +0300
commit664aed04446c7f653d8acbe2cdf7989f28238524 (patch)
treec24892772b01314b2f060be64e3c7ae1f36e6298 /Documentation/admin-guide
parent3418d036c81dcb604b7c7c71b209d5890a8418aa (diff)
downloadlinux-664aed04446c7f653d8acbe2cdf7989f28238524.tar.xz
md: add sysfs entries for PPL
Add 'consistency_policy' attribute for array. It indicates how the array maintains consistency in case of unexpected shutdown. Add 'ppl_sector' and 'ppl_size' for rdev, which describe the location and size of the PPL space on the device. They can't be changed for active members if the array is started and PPL is enabled, so in the setter functions only basic checks are performed. More checks are done in ppl_validate_rdev() when starting the log. These attributes are writable to allow enabling PPL for external metadata arrays and (later) to enable/disable PPL for a running array. Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com> Signed-off-by: Shaohua Li <shli@fb.com>
Diffstat (limited to 'Documentation/admin-guide')
-rw-r--r--Documentation/admin-guide/md.rst32
1 files changed, 29 insertions, 3 deletions
diff --git a/Documentation/admin-guide/md.rst b/Documentation/admin-guide/md.rst
index 1e61bf50595c..84de718f24a4 100644
--- a/Documentation/admin-guide/md.rst
+++ b/Documentation/admin-guide/md.rst
@@ -276,14 +276,14 @@ All md devices contain:
array creation it will default to 0, though starting the array as
``clean`` will set it much larger.
- new_dev
+ new_dev
This file can be written but not read. The value written should
be a block device number as major:minor. e.g. 8:0
This will cause that device to be attached to the array, if it is
available. It will then appear at md/dev-XXX (depending on the
name of the device) and further configuration is then possible.
- safe_mode_delay
+ safe_mode_delay
When an md array has seen no write requests for a certain period
of time, it will be marked as ``clean``. When another write
request arrives, the array is marked as ``dirty`` before the write
@@ -292,7 +292,7 @@ All md devices contain:
period as a number of seconds. The default is 200msec (0.200).
Writing a value of 0 disables safemode.
- array_state
+ array_state
This file contains a single word which describes the current
state of the array. In many cases, the state can be set by
writing the word for the desired state, however some states
@@ -401,7 +401,30 @@ All md devices contain:
once the array becomes non-degraded, and this fact has been
recorded in the metadata.
+ consistency_policy
+ This indicates how the array maintains consistency in case of unexpected
+ shutdown. It can be:
+ none
+ Array has no redundancy information, e.g. raid0, linear.
+
+ resync
+ Full resync is performed and all redundancy is regenerated when the
+ array is started after unclean shutdown.
+
+ bitmap
+ Resync assisted by a write-intent bitmap.
+
+ journal
+ For raid4/5/6, journal device is used to log transactions and replay
+ after unclean shutdown.
+
+ ppl
+ For raid5 only, Partial Parity Log is used to close the write hole and
+ eliminate resync.
+
+ The accepted values when writing to this file are ``ppl`` and ``resync``,
+ used to enable and disable PPL.
As component devices are added to an md array, they appear in the ``md``
@@ -563,6 +586,9 @@ Each directory contains:
adds bad blocks without acknowledging them. This is largely
for testing.
+ ppl_sector, ppl_size
+ Location and size (in sectors) of the space used for Partial Parity Log
+ on this device.
An active md device will also contain an entry for each active device