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Re: mdadm on lenny64, why two spares?



In Tuesday 09 June 2009, you wrote:
>On Tue, 09 Jun 2009 17:30 -0500, "Boyd Stephen Smith Jr."
><bss@iguanasuicide.net> wrote:
>> In <1244582859.18981.1319594151@webmail.messagingengine.com>,
>> whollygoat@letterboxes.org wrote:
>> >On Tue, 09 Jun 2009 11:26 +1000, "Alex Samad" <alex@samad.com.au> wrote:
>> >> On Mon, Jun 08, 2009 at 03:45:22PM -0700, whollygoat@letterboxes.org
>> >> wrote:
>> >> > cat /proc/mdstat
>> >> > Personalities : [raid6] [raid5] [raid4]
>> >> > md0 : active (auto-read-only) raid5 hdi1[4](S) hdk1[3](S) hdg1[1]
>> >I am wondering what put it into read-only mode.
>> It was in auto-read-only (not quite the same).  Auto-read-only is set
>> automatically by mdadm for array that is started without all of it's
>> devices.  It prevents mdadm from starting a rebuild until the array is
>> written to (or forced into read-write mode).  This is to allow the
>> incremental build system to work sanely when spares are detected before
>> all the active devices.
>Is this behaviour related to what is described in the following mdadm
>changelog.Debian.gz?:

Perhaps, although the auto-read-only state is not just set in an initramfs; 
it is build into the mdadm start code, as best as I can tell.

>I ask because the array wasn't started during boot, but during creation.
> Even if so, I'm afraid I don't understand why this happened in my case
>because the array was created (started) with all it's devices.

No, it wasn't.  Again, it was mdadm being "smart" and starting your array 
with the last device missing but with an extra spare.  Thus, the device 
didn't have all of it's active devices and started in auto-read-only.
-- 
Boyd Stephen Smith Jr.           	 ,= ,-_-. =.
bss@iguanasuicide.net            	((_/)o o(\_))
ICQ: 514984 YM/AIM: DaTwinkDaddy 	 `-'(. .)`-'
http://iguanasuicide.net/        	     \_/

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