Re: Expanding size of existing raid1 md device

["Mike Black" <mblack@csi-inc.com>]

I've done this with a single partition but it should work for multiple also.

Sounds like you already partioned the new 36G correctly.
Before you insert the new 36G disk you need to re-create the raid array and resize the file system:
Let's assume you've already sync'd hda to the 36G hdc and replaced hda with a brand-new 36G
mdadm --create /dev/md0 -l1 -n2 /dev/hdc1 missing
resize2fs -p -f /dev/md0
e2fsck -C 0 /dev/md0
mdadm --add /dev/md0 /dev/hda1

And repeat for md1

----- Original Message ----- 
From: "Sean Kormilo" <skormilo@nortelnetworks.com>
To: "linux-raid" <linux-raid@vger.kernel.org>
Sent: Thursday, April 24, 2003 2:48 PM
Subject: Expanding size of existing raid1 md device


> Hi,
> 
> I'm wondering if there is any way to do the following...
> 
> Assume I've got a system with 2 18GB disks. Each disk has 2 partitons
> which are then setup as mirrored md devices.
> /dev/md0 uses small 100MB partitions on each drive
> /dev/md1 uses the rest of each disk (ie: ~17.9GB)
> 
> I'd like to be able to upgrade the system to use 36GB disks, such that
> the /dev/md1 partition expands to take up the rest of the additional
> space provided by the 36GB disk.
> 
> So, the process might look something like:
> - fail and remove the partition for both md arrays
> - remove 1 of the 18GB disks
> - insert new 36GB disk
> - partition 36GB disk with 100MB partition for /dev/md0
> - partition 36GB disk with 35.9GB partition for /dev/md1
> - hotadd the 36GB disk partitions so that it syncs with 18GB disk
> - wait for sync to complete
> - fail and remove the partitions on both md arrays on the 18GB disk
> - remove the 18GB disk
> - insert new 36GB disk
> - partition 36GB disk with 100MB partition for /dev/md0
> - partition 36GB disk with 35.9GB partition for /dev/md1
> - hotadd the 36GB disk partitions so that it syncs with the other 36GB
> disk
> 
> Having tried this, it works except that /dev/md1 does not make use of
> the additional space provided by the 36GB disks even though the
> partitions on both disks are larger. It appears to me that it is using
> the value from the superblock when the array was created (which makes
> sense).
> 
> Is there some way to force the md driver to expand to use the maximum
> size available based on the disks/partitions in the array? Perhaps from
> mdadm? Or is some kind of patch to the kernel required to make this
> work? If so, any pointers as to where I'd look?
> 
> Thanks!
> 
> Sean.
> 
> 
> 
> 
> -- 
> 
> Sean C. Kormilo, STORM Software Architect, Nortel Networks
>               email: skormilo@nortelnetworks.com
>   
> 
> -
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