New device for RAID array

I read through the man page for mdadm a couple of times and did not spot how
to do this. I currently have a RAID array that I need to upgrade from 1T
drives to 3T drives. To accomplish this, I intend to create a larger array,
but with fewer spindles, and then rsync the contents of the old array to the
new. Once I am done, I then want to stop the old array (/dev/md0) and start
up the new array under /dev/md0. Do I have to stop the array and then
re-create it with all the same parameters, except the device target?

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Re: New device for RAID array

On Thu, 12 May 2011 19:59:01 -0500 "Leslie Rhorer"
wrote:

>
> I read through the man page for mdadm a couple of times and did not spot how
> to do this. I currently have a RAID array that I need to upgrade from 1T
> drives to 3T drives. To accomplish this, I intend to create a larger array,
> but with fewer spindles, and then rsync the contents of the old array to the
> new. Once I am done, I then want to stop the old array (/dev/md0) and start
> up the new array under /dev/md0. Do I have to stop the array and then
> re-create it with all the same parameters, except the device target?

For v0.90: --update=super-minor
For v1.x --update=name

NeilBrown
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RE: New device for RAID array

> -----Original Message-----
> From: NeilBrown [mailto:neilb@suse.de]
> Sent: Thursday, May 12, 2011 8:21 PM
> To: lrhorer@satx.rr.com
> Cc: linux-raid@vger.kernel.org
> Subject: Re: New device for RAID array
>
> On Thu, 12 May 2011 19:59:01 -0500 "Leslie Rhorer"
> wrote:
>
> >
> > I read through the man page for mdadm a couple of times and did not spot
> how
> > to do this. I currently have a RAID array that I need to upgrade from
> 1T
> > drives to 3T drives. To accomplish this, I intend to create a larger
> array,
> > but with fewer spindles, and then rsync the contents of the old array to
> the
> > new. Once I am done, I then want to stop the old array (/dev/md0) and
> start
> > up the new array under /dev/md0. Do I have to stop the array and then
> > re-create it with all the same parameters, except the device target?
>
> For v0.90: --update=super-minor
> For v1.x --update=name

Um, it will be a 1.2 array, so I take it if the current array is
/dev/md0, named RAID-Server:0 from /dev/sd[a-n], and the new array is
something like /dev/md4, named RAID-Server:4 from sd[q-x], then I stop both
arrays and enter

mdadm --assemble /dev/md0 /dev/sd[q-x] --update=name

Correct? Of course then I need to update /etc/mdadm/mdadm.conf and
run `update-initrd`.

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Re: New device for RAID array

On Fri, 13 May 2011 00:37:02 -0500 "Leslie Rhorer"
wrote:

> > -----Original Message-----
> > From: NeilBrown [mailto:neilb@suse.de]
> > Sent: Thursday, May 12, 2011 8:21 PM
> > To: lrhorer@satx.rr.com
> > Cc: linux-raid@vger.kernel.org
> > Subject: Re: New device for RAID array
> >
> > On Thu, 12 May 2011 19:59:01 -0500 "Leslie Rhorer"
> > wrote:
> >
> > >
> > > I read through the man page for mdadm a couple of times and did not spot
> > how
> > > to do this. I currently have a RAID array that I need to upgrade from
> > 1T
> > > drives to 3T drives. To accomplish this, I intend to create a larger
> > array,
> > > but with fewer spindles, and then rsync the contents of the old array to
> > the
> > > new. Once I am done, I then want to stop the old array (/dev/md0) and
> > start
> > > up the new array under /dev/md0. Do I have to stop the array and then
> > > re-create it with all the same parameters, except the device target?
> >
> > For v0.90: --update=super-minor
> > For v1.x --update=name
>
> Um, it will be a 1.2 array, so I take it if the current array is
> /dev/md0, named RAID-Server:0 from /dev/sd[a-n], and the new array is
> something like /dev/md4, named RAID-Server:4 from sd[q-x], then I stop both
> arrays and enter
>
> mdadm --assemble /dev/md0 /dev/sd[q-x] --update=name
>
> Correct? Of course then I need to update /etc/mdadm/mdadm.conf and
> run `update-initrd`.

Yes, though you don't really need to change the name on the array unless you
particularly want to. Just changing mdadm.conf is enough to get it assembled
as the "right" place.

I think the command you give will store "RAID-Server:0" in the metadata
assuming 'hostname' or HOMEHOST in mdadm.conf is RAID-Server, but if it
doesn't you can experiment with explicitly setting --name and --hostname on
the command line.

NeilBrown

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RE: New device for RAID array

Thanks.

> -----Original Message-----
> From: NeilBrown [mailto:neilb@suse.de]
> Sent: Friday, May 13, 2011 12:51 AM
> To: lrhorer@satx.rr.com
> Cc: linux-raid@vger.kernel.org
> Subject: Re: New device for RAID array
>
> On Fri, 13 May 2011 00:37:02 -0500 "Leslie Rhorer"
> wrote:
>
> > > -----Original Message-----
> > > From: NeilBrown [mailto:neilb@suse.de]
> > > Sent: Thursday, May 12, 2011 8:21 PM
> > > To: lrhorer@satx.rr.com
> > > Cc: linux-raid@vger.kernel.org
> > > Subject: Re: New device for RAID array
> > >
> > > On Thu, 12 May 2011 19:59:01 -0500 "Leslie Rhorer"
>
> > > wrote:
> > >
> > > >
> > > > I read through the man page for mdadm a couple of times and did not
> spot
> > > how
> > > > to do this. I currently have a RAID array that I need to upgrade
> from
> > > 1T
> > > > drives to 3T drives. To accomplish this, I intend to create a
> larger
> > > array,
> > > > but with fewer spindles, and then rsync the contents of the old
> array to
> > > the
> > > > new. Once I am done, I then want to stop the old array (/dev/md0)
> and
> > > start
> > > > up the new array under /dev/md0. Do I have to stop the array and
> then
> > > > re-create it with all the same parameters, except the device target?
> > >
> > > For v0.90: --update=super-minor
> > > For v1.x --update=name
> >
> > Um, it will be a 1.2 array, so I take it if the current array is
> > /dev/md0, named RAID-Server:0 from /dev/sd[a-n], and the new array is
> > something like /dev/md4, named RAID-Server:4 from sd[q-x], then I stop
> both
> > arrays and enter
> >
> > mdadm --assemble /dev/md0 /dev/sd[q-x] --update=name
> >
> > Correct? Of course then I need to update /etc/mdadm/mdadm.conf and
> > run `update-initrd`.
>
> Yes, though you don't really need to change the name on the array unless
> you
> particularly want to. Just changing mdadm.conf is enough to get it
> assembled
> as the "right" place.
>
> I think the command you give will store "RAID-Server:0" in the metadata
> assuming 'hostname' or HOMEHOST in mdadm.conf is RAID-Server, but if it
> doesn't you can experiment with explicitly setting --name and --hostname
> on
> the command line.
>
> NeilBrown


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