How does one assemble a DDF or IMSM array?

How does one assemble a DDF or IMSM array?

[Wakko Warner]

I've not used DDF or IMSM arrays much.

I understand that the devices (ie /dev/sda and /dev/sdb) are the containers.

I know that one can use mdadm -I on the devices and it will create mdXXX
(last I tried it was 127) and then will create mdXXX for each virtual disk
in the container and they will just work.

If I do mdadm -A /dev/mdXXX, how would one get the volumes inside started?
I tried mdadm -I /dev/mdXXX after mdadm -A.  It created mdXXX where XXX is
-2 from the first one (it 127 being the container and 125 being there but
not in a state that works)

Does DDF/IMSM require mdadm.conf to work when using -A?

I'm not sure if I'm making myself very clear here or not.

-- 
 Microsoft has beaten Volkswagen's world record.  Volkswagen only created 22
 million bugs.

How does one assemble a DDF or IMSM array?

[Wakko Warner]

I've not used DDF or IMSM arrays much.

I understand that the devices (ie /dev/sda and /dev/sdb) are the containers.

I know that one can use mdadm -I on the devices and it will create mdXXX
(last I tried it was 127) and then will create mdXXX for each virtual disk
in the container and they will just work.

If I do mdadm -A /dev/mdXXX, how would one get the volumes inside started?
I tried mdadm -I /dev/mdXXX after mdadm -A.  It created mdXXX where XXX is
-2 from the first one (it 127 being the container and 125 being there but
not in a state that works)

Does DDF/IMSM require mdadm.conf to work when using -A?

I'm not sure if I'm making myself very clear here or not.

-- 
 Microsoft has beaten Volkswagen's world record.  Volkswagen only created 22
 million bugs.

Re: How does one assemble a DDF or IMSM array?

[Albert Pauw]

Hi,

you can start them by using "mdadm -As", that will start up the 
container first and the other md devices after.
This will work without mdadm.conf, but it is always good to create a 
proper mdadm.conf (mdadm -Es > /etc/mdadm.conf).

As for what it is, the container contains the disks (in your case sda 
and sdb), the disks are not the container.

So you create a container first:
mdadm -CR /dev/md127 -e ddf -l container -n 2 /dev/sda /dev/sdb
Create a RAID1 device of 1 GB in there
mdadm -CR /dev/md0 -l 1 -n 2 /dev/md127 -z  1G
Create another RAID1 device of 50 MB in there
mdadm -CR /dev/md1 -l 1 -n 2 /dev/md127 -z 50M

(in this case both md devices are created on the same two disks).

If you have e.g. 5 disks you can create two separate RAID1 and RAID5 
devices in the container:

mdadm -CR /dev/md127 -e ddf -l container -n 2 /dev/sda /dev/sdb /dev/sdc 
/dev/sdd /dev/sde
mdadm -CR /dev/md0 -l 1 -n 2 /dev/md127
mdadm -CR /dev/md1 -l 5 -n 3 /dev/md127

Now, two disk are used fully for the RAID 1 device and three fully for 
the RAID 5 devices, they both have their own set of disks.


Stopping them all:
mdadm -Ss

Starting them all:
mdadm -As

Hope this helps,

Albert


On 08/03/2012 03:05 AM, Wakko Warner wrote:
> I've not used DDF or IMSM arrays much.
>
> I understand that the devices (ie /dev/sda and /dev/sdb) are the containers.
>
> I know that one can use mdadm -I on the devices and it will create mdXXX
> (last I tried it was 127) and then will create mdXXX for each virtual disk
> in the container and they will just work.
>
> If I do mdadm -A /dev/mdXXX, how would one get the volumes inside started?
> I tried mdadm -I /dev/mdXXX after mdadm -A.  It created mdXXX where XXX is
> -2 from the first one (it 127 being the container and 125 being there but
> not in a state that works)
>
> Does DDF/IMSM require mdadm.conf to work when using -A?
>
> I'm not sure if I'm making myself very clear here or not.
>

Re: How does one assemble a DDF or IMSM array?

[Wakko Warner]

Albert Pauw wrote:
> you can start them by using "mdadm -As", that will start up the
> container first and the other md devices after.
> This will work without mdadm.conf, but it is always good to create a
> proper mdadm.conf (mdadm -Es > /etc/mdadm.conf).
> 
> As for what it is, the container contains the disks (in your case
> sda and sdb), the disks are not the container.
> 
> So you create a container first:
> mdadm -CR /dev/md127 -e ddf -l container -n 2 /dev/sda /dev/sdb
> Create a RAID1 device of 1 GB in there
> mdadm -CR /dev/md0 -l 1 -n 2 /dev/md127 -z  1G
> Create another RAID1 device of 50 MB in there
> mdadm -CR /dev/md1 -l 1 -n 2 /dev/md127 -z 50M
> 
> (in this case both md devices are created on the same two disks).
> 
> If you have e.g. 5 disks you can create two separate RAID1 and RAID5
> devices in the container:
> 
> mdadm -CR /dev/md127 -e ddf -l container -n 2 /dev/sda /dev/sdb
> /dev/sdc /dev/sdd /dev/sde
> mdadm -CR /dev/md0 -l 1 -n 2 /dev/md127
> mdadm -CR /dev/md1 -l 5 -n 3 /dev/md127
> 
> Now, two disk are used fully for the RAID 1 device and three fully
> for the RAID 5 devices, they both have their own set of disks.

I created 2 ddf disks in a container on /dev/sd[ab].  I had 3 MD devices at
that time.

> Stopping them all:
> mdadm -Ss
> 
> Starting them all:
> mdadm -As

This did stop the devices, but would not start them back up.  mdadm 3.2.5
was used.

In your example, suppose I have md0 in use and md1 was not in use and was
stopped.  How would I get md1 started back up w/o shuttind down md0 and
md127?

-- 
 Microsoft has beaten Volkswagen's world record.  Volkswagen only created 22
 million bugs.