Re: Adding disks with raid to existing raid system.

[Simon Matthews <simon.d.matthews@gmail.com>]

On Mon, Mar 15, 2010 at 9:59 PM, Michael Evans <mjevans1983@gmail.com> wrote:
> On Mon, Mar 15, 2010 at 7:53 PM, Simon Matthews
> <simon.d.matthews@gmail.com> wrote:
>> On Mon, Mar 15, 2010 at 5:36 PM, Michael Evans <mjevans1983@gmail.com> wrote:
>>> On Sun, Mar 14, 2010 at 10:23 PM, Simon Matthews
>>> <simon.d.matthews@gmail.com> wrote:
>>>> I have just built a system and have it booting off a software raid
>>>> partition. The raid sets use devices /dev/md0, /dev/hd1, /dev/md2,
>>>> /dev/md3.
>>>>
>>>> I now need to transfer some additional disks to this system. These
>>>> disks are presently in another system where they host a number of raid
>>>> sets, currently also /dev/md0 - /dev/md4.
>>>>
>>>> I need to ensure that the data on the raid set that I am adding to the
>>>> system is not lost. However, clearly, I can't have the raid sets on
>>>> these disks come up as /dev/md0-md4. How do I ensure this and have
>>>> these raid sets come up on /dev/md5 and higher?
>>>>
>>>> Simon
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>>>
>>> Either use an mdadm.conf to specify the mapping of UUID to md device
>>> (which will over-ride any auto-detected requests), or use the
>>> home-host fallback.  Obviously the administrator specifying how they'd
>>> prefer mdadm to assemble the drives is preferable.
>>
>> I'm not aware of the "home-host fallback" can you give me some pointers on this?
>>>
>>> You will probably want to regenerate your initrd; if you are using
>>> auto-assembly on root without an initrd, I highly suggest upgrading to
>>> use an initrd/initramfs.  You might find this one easy to customize
>>> for your needs if your distribution lacks one or you dislike the one
>>> it generates: http://sourceforge.net/projects/aeuio/
>>
>> Fortunately Gentoo includes mkinitrd so I can try this if other
>> methods don't work reliably.
>>
>> Simon
>>
>>>
>>
>
> man mdadm
> /host
>
> --homehost=
>
> This will override any HOMEHOST setting in the config file and
> provides the identity of the host which should be considered the home
> for any arrays.
>
> ... etc
>
> Before asking any further questions I highly suggest reading the
> manual, completely, at least twice.
>

In my defense, I did try to google this, but I looked for "home-host"
or "home host" and nothing turned up. Many thanks for your help. I
think this will solve my question about added existing arrays to a
system.

Simon
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