problem growing raid-1

problem growing raid-1

[Troy Cauble]

I want to replace both disks in a RAID-1 with larger ones using the
instructions here:
http://linux-raid.osdl.org/index.php/Growing#Extending_an_existing_RAID_array

It looks straightforward: mdadm -f, mdmadm -r, swap a drive, etc., etc.

Except if I -f & -r a drive, I won't know which physical drive to pull.
(And I have no spare SATA ports.)

So I figure I'll pull a drive first, then -f & -r whatever mdadm tells
me is missing.
But when I pull the drive, connect a new one and boot, I get dropped
into a repair
shell with:

fsck.ext3: Unable to resolve 'UUID=806153bf-6917-440d-ae48-553418cfbbeb'

which is the UUID of the raid filesystem.

I put the drive back in and reboot, and everything is fine.

1)  So why doesn't my RAID-1 survive pulling a drive?
Seems like a standard failure mode.

2)  How do I proceed with the upgrade?

Thanks,
-troy

RE: problem growing raid-1

[Guy Watkins]

Years ago I had a problem booting with a failed disk.  I was told to add
this to the kernel command line.

md-mod.start_dirty_degraded=1

For me the file to edit is this:  /boot/grub/grub.conf

I think the above should be the default.  During a failure is not the time
to learn this!  Or it should be an attribute of the array, so you can have
some arrays that can start degraded and some that can't.

Guy

} -----Original Message-----
} From: linux-raid-owner@vger.kernel.org [mailto:linux-raid-
} owner@vger.kernel.org] On Behalf Of Troy Cauble
} Sent: Sunday, February 01, 2009 12:35 AM
} To: linux-raid@vger.kernel.org
} Subject: problem growing raid-1
} 
} I want to replace both disks in a RAID-1 with larger ones using the
} instructions here:
} http://linux-
} raid.osdl.org/index.php/Growing#Extending_an_existing_RAID_array
} 
} It looks straightforward: mdadm -f, mdmadm -r, swap a drive, etc., etc.
} 
} Except if I -f & -r a drive, I won't know which physical drive to pull.
} (And I have no spare SATA ports.)
} 
} So I figure I'll pull a drive first, then -f & -r whatever mdadm tells
} me is missing.
} But when I pull the drive, connect a new one and boot, I get dropped
} into a repair
} shell with:
} 
} fsck.ext3: Unable to resolve 'UUID=806153bf-6917-440d-ae48-553418cfbbeb'
} 
} which is the UUID of the raid filesystem.
} 
} I put the drive back in and reboot, and everything is fine.
} 
} 1)  So why doesn't my RAID-1 survive pulling a drive?
} Seems like a standard failure mode.
} 
} 2)  How do I proceed with the upgrade?
} 
} Thanks,
} -troy
} --
} To unsubscribe from this list: send the line "unsubscribe linux-raid" in
} the body of a message to majordomo@vger.kernel.org
} More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: problem growing raid-1

[Troy Cauble]

Thanks, but...

I had another problem recently and it the system DID boot with the
RAID degraded.  (In fact, I posted a Q here 12 days ago about
putting my degraded raid back together.)

Also, the documentation I can find on md-mod.start_dirty_degraded=1
says it's for RAID 5 or 6 and root filesystems.  Mine is RAID-1 and /home.

Any other ideas?
-troy


On Sun, Feb 1, 2009 at 1:58 AM, Guy Watkins <linux-raid@watkins-home.com> wrote:
> Years ago I had a problem booting with a failed disk.  I was told to add
> this to the kernel command line.
>
> md-mod.start_dirty_degraded=1
>
> For me the file to edit is this:  /boot/grub/grub.conf
>
> I think the above should be the default.  During a failure is not the time
> to learn this!  Or it should be an attribute of the array, so you can have
> some arrays that can start degraded and some that can't.
>
> Guy
>
> } -----Original Message-----
> } From: linux-raid-owner@vger.kernel.org [mailto:linux-raid-
> } owner@vger.kernel.org] On Behalf Of Troy Cauble
> } Sent: Sunday, February 01, 2009 12:35 AM
> } To: linux-raid@vger.kernel.org
> } Subject: problem growing raid-1
> }
> } I want to replace both disks in a RAID-1 with larger ones using the
> } instructions here:
> } http://linux-
> } raid.osdl.org/index.php/Growing#Extending_an_existing_RAID_array
> }
> } It looks straightforward: mdadm -f, mdmadm -r, swap a drive, etc., etc.
> }
> } Except if I -f & -r a drive, I won't know which physical drive to pull.
> } (And I have no spare SATA ports.)
> }
> } So I figure I'll pull a drive first, then -f & -r whatever mdadm tells
> } me is missing.
> } But when I pull the drive, connect a new one and boot, I get dropped
> } into a repair
> } shell with:
> }
> } fsck.ext3: Unable to resolve 'UUID=806153bf-6917-440d-ae48-553418cfbbeb'
> }
> } which is the UUID of the raid filesystem.
> }
> } I put the drive back in and reboot, and everything is fine.
> }
> } 1)  So why doesn't my RAID-1 survive pulling a drive?
> } Seems like a standard failure mode.
> }
> } 2)  How do I proceed with the upgrade?
> }
> } Thanks,
> } -troy
> } --
> } To unsubscribe from this list: send the line "unsubscribe linux-raid" in
> } the body of a message to majordomo@vger.kernel.org
> } More majordomo info at  http://vger.kernel.org/majordomo-info.html
>
>

Re: problem growing raid-1

[Richard Scobie]

Troy Cauble wrote:
> I want to replace both disks in a RAID-1 with larger ones using the
> instructions here:
> http://linux-raid.osdl.org/index.php/Growing#Extending_an_existing_RAID_array
> 
> It looks straightforward: mdadm -f, mdmadm -r, swap a drive, etc., etc.
> 
> Except if I -f & -r a drive, I won't know which physical drive to pull.
> (And I have no spare SATA ports.)

smartctl -a -d ata /dev/sdx

will tell you the serial number of the drive, which then lets you 
shutdown, identify and remove the correct one.

Regards,

Richard

Re: problem growing raid-1

[Troy Cauble]

On Sun, Feb 1, 2009 at 1:56 PM, Richard Scobie <richard@sauce.co.nz> wrote:
> Troy Cauble wrote:
>>
>> I want to replace both disks in a RAID-1 with larger ones using the
>> instructions here:
>>
>> http://linux-raid.osdl.org/index.php/Growing#Extending_an_existing_RAID_array
>>
>> It looks straightforward: mdadm -f, mdmadm -r, swap a drive, etc., etc.
>>
>> Except if I -f & -r a drive, I won't know which physical drive to pull.
>> (And I have no spare SATA ports.)
>
> smartctl -a -d ata /dev/sdx
>
> will tell you the serial number of the drive, which then lets you shutdown,
> identify and remove the correct one.
>
> Regards,
>
> Richard

Thanks,

Since my original post, I found out about getting the serial number
via smartctl or hdparm.

But before I start failing and removing drives, I'd like to understand
why my set up didn't handle a physically removed drive.  Because
if that happens after the -f & -r, then I'm really stuck.

Thanks,
-troy