From 9ab6e80a04532e55eb58ea4d320ed1104c8df1d6 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Wed, 27 Jul 2011 14:06:13 +1000 Subject: mdadm.8.in: clarify some issues with --size - explain it's use in guarding against small replacements - clarify relationship with containers. - include information about --grow --size not being supported by IMSM metadata. Reported-by: maciej.naruszewicz Signed-off-by: NeilBrown --- mdadm.8.in | 28 +++++++++++++++++++++------- 1 file changed, 21 insertions(+), 7 deletions(-) diff --git a/mdadm.8.in b/mdadm.8.in index 7e8981e..e22fde4 100644 --- a/mdadm.8.in +++ b/mdadm.8.in @@ -418,11 +418,22 @@ issued. A suffix of 'M' or 'G' can be given to indicate Megabytes or Gigabytes respectively. +Sometimes a replacement drive can be a little smaller than the +original drives though this should be minimised by IDEMA standards. +Such a replacement drive will be rejected by +.IR md . +To guard against this it can be useful to set the initial size +slightly smaller than the smaller device with the aim that it will +still be larger than any replacement. + This value can be set with .B \-\-grow -for RAID level 1/4/5/6. If the array was created with a size smaller -than the currently active drives, the extra space can be accessed -using +for RAID level 1/4/5/6 though +.B CONTAINER +based arrays such as those with IMSM metadata may not be able to +support this. +If the array was created with a size smaller than the currently +active drives, the extra space can be accessed using .BR \-\-grow . The size can be given as .B max @@ -440,9 +451,10 @@ problems the array can be made bigger again with no loss with another .B "\-\-grow \-\-size=" command. -This value can not be used with +This value cannot be used when creating a .B CONTAINER -metadata such as DDF and IMSM. +such as with DDF and IMSM metadata, though it perfectly valid when +creating an array inside a container. .TP .BR \-Z ", " \-\-array\-size= @@ -2215,12 +2227,14 @@ add a write-intent bitmap to any array which supports these bitmaps, or remove a write-intent bitmap from such an array. .PP -Using GROW on containers is currently only support for Intel's IMSM +Using GROW on containers is currently supported only for Intel's IMSM container format. The number of devices in a container can be increased - which affects all arrays in the container - or an array in a container can be converted between levels where those levels are supported by the container, and the conversion is on of those listed -above. +above. Resizing arrays in an IMSM container with +.B "--grow --size" +is not yet supported. Grow functionality (e.g. expand a number of raid devices) for Intel's IMSM container format has an experimental status. It is guarded by the -- cgit v1.2.1