Re: mdadm on lenny64, why two spares?

[whollygoat@letterboxes.org]

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:
> >> > On Mon, 08 Jun 2009 17:07 +0100, "kj"
> >> > <koffiejunkielistlurker@koffiejunkie.za.net> wrote:
> >> > > What does `cat /proc/mdstat` show you?
> >> > cat /proc/mdstat
> >> > Personalities : [raid6] [raid5] [raid4]
> >> > md0 : active (auto-read-only) raid5 hdi1[4](S) hdk1[3](S) hdg1[1]
> >> I believe you are in READ ONLY MODE, it will not attempt to put the
> >> spares back into to the array until it is moved into read/write
> >>
> >> mdadm -w /dev/md0
> >Right you are.  The third drive was synced into the array with the above
> >command.
> >
> >But, now 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?:

   mdadm (2.6.1-1) unstable: urgency=low
     ...
     * Start arays read-only in initramfs to prevent syncing and hence   
       enable resuming/freezing. The arrays will automatically sync as  
       soon something writes to it...

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.

Can you explain what I am missing something here?

Thanks,

will
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  whollygoat@letterboxes.org

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