Increase raid456 stripe cache size if needed to --grow the array.

[thirdparty/mdadm.git] / mdadm.8

diff --git a/mdadm.8 b/mdadm.8
index 076ee637496dfdb64f6d659817bace00978b7d13..274609c17180676c953473413faa455b9fb23815 100644 (file)
--- a/mdadm.8
+++ b/mdadm.8
@@ -5,7 +5,7 @@
 '''   the Free Software Foundation; either version 2 of the License, or
 '''   (at your option) any later version.
 ''' See file COPYING in distribution for details.
-.TH MDADM 8 "" v2.5.3
+.TH MDADM 8 "" v2.5.6
 .SH NAME
 mdadm \- manage MD devices
 .I aka
@@ -273,6 +273,12 @@ says to get a list of array devices from
 .B -e ", " --metadata=
 Declare the style of superblock (raid metadata) to be used.  The
 default is 0.90 for --create, and to guess for other operations.
+The default can be overridden by setting the
+.B metadata
+value for the
+.B CREATE
+keyword in
+.BR mdadm.conf .
 
 Options are:
 .RS
@@ -567,6 +573,10 @@ from this.  See DEVICE NAMES below.
 The argument can also come immediately after
 "-a".  e.g. "-ap".
 
+If --auto is not given on the command line or in the config file, then
+the default will be
+.BR --auto=yes .
+
 If
 .I --scan
 is also given, then any
@@ -706,6 +716,7 @@ argument given to this flag can be one of
 .BR homehost ,
 .BR resync ,
 .BR byteorder ,
+.BR devicesize ,
 or
 .BR super-minor .
 
@@ -783,6 +794,22 @@ The
 option will correct the summaries in the superblock. That is the
 counts of total, working, active, failed, and spare devices.
 
+The
+.B devicesize
+will rarely be of use.  It applies to version 1.1 and 1.2 metadata
+only (where the metadata is at the start of the device) and is only
+useful when the component device has changed size (typically become
+larger).  The version 1 metadata records the amount of the device that
+can be used to store data, so if a device in a version 1.1 or 1.2
+array becomes larger, the metadata will still be visible, but the
+extra space will not.  In this case it might be useful to assemble the
+array with
+.BR --update=devicesize .
+This will cause
+.I mdadm
+to determine the maximum usable amount of space on each device and
+update the relevant field in the metadata.
+
 .TP
 .B --auto-update-homehost
 This flag is only meaning with auto-assembly (see discussion below).
@@ -1037,13 +1064,11 @@ may work for RAID1, 4, 5, 6, or 10), give the
 .B --run
 flag.
 
-If an
-.B auto
-option is given, either on the command line (--auto) or in the
-configuration file (e.g. auto=part), then
-.I mdadm
-will create the md device if necessary or will re-create it if it
-doesn't look usable as it is.
+If the md device does not exist, then it will be created providing the
+intent is clear. i.e. the name must be in a standard form, or the
+.I --auto
+option must be given to clarify how and whether the device should be
+created.
 
 This can be useful for handling partitioned devices (which don't have
 a stable device number - it can change after a reboot) and when using