Can't *write* to a hard disk, not even a slice using fdisk(8).

[Julien Gabel]

>>> GEOM doesn't let you write to an active device, except if you set
>>> kern.geom.debugflags=16

>> Ok no problem, I changed it this way:
>>  # sysctl kern.geom.debugflags=16
>>  kern.geom.debugflags: 1 -> 16
>> But it seems to change *absolutly nothing*... :(

> Mmmhh... We're doing something wrong here I guess :o Are you 100% sure
> that ad10 is not used by any open geom modules? What does dmesg say
> about ar*?

What we ca note is that:
 - The machine was booted without using this drive at all (nor in a 'ar'
   array, nor alone via 'ad10');
 - GEOM create an entry for this device during the boot proccess (see
   below), but there is no reference to use it from the OS point of view
   (/etc/fstab, etc.).
 - How can I _really_ know that this drive is not used by geom?

 # dmesg | tail -50
 [...]
 GEOM: create disk ad4 dp=0xc6cb6360
 ad4: 78167MB <Maxtor 6Y080P0> [158816/16/63] at ata2-master UDMA133
 GEOM: create disk ad6 dp=0xc6ab2960
 ad6: 78167MB <Maxtor 6Y080P0> [158816/16/63] at ata3-master UDMA133
 GEOM: create disk ad8 dp=0xc6ab2560
 ad8: 117246MB <Maxtor 6Y120P0> [238216/16/63] at ata4-master UDMA133
 GEOM: create disk ad10 dp=0xc6ab2660
 ad10: 117246MB <Maxtor 6Y120P0> [238216/16/63] at ata5-master UDMA133
 GEOM: create disk ar0 dp=0xc6aae5e0
 ar0: 78167MB <ATA RAID1 array> [9964/255/63] status: READY subdisks:
  disk0 READY on ad4 at ata2-master
  disk1 READY on ad6 at ata3-master
 Mounting root from ufs:/dev/ar0s1a
 g_slice_config(ad10, 0, 0)
 g_slice_config(ad10, 1, 0)
 g_slice_config(ad10, 2, 0)
 g_slice_config(ad10, 3, 0)
 g_slice_config(ad10, 0, 1)
 g_slice_config(ad10, 1, 1)
 g_slice_config(ad10, 2, 1)
 g_slice_config(ad10, 3, 1)

This is what we can expected to see: the only 'ar' array which exist now
is the first mirror for system part. There is no second array, since I
made /home only available on /dev/ad8 and not /dev/ar1s1d. I don't see
anything wrong here(?). Am I missing something?

> After reading man geom (see the fine print under SPOILING), maybe you
> should take this up on current@, pointing to this thread and posting the
> following information (better in single user mode, if you have a console):

Good pointer... which may explains the problem I encountered.

> 0. dmesg
> 1. your RAID array configuration
> 2. your currently mounted partitions
> 3. the output of the fdisk command

I will... after doing a swap and test this drive in an other machine to
test it with other hardware(controller) and OS to avoid some mistake on
my side.

Thanks for your help,
-- 
-jpeg.