Re: LVM & RAID10

[Bean]

On Thu, Dec 4, 2008 at 6:32 AM, Wojciech Pyczak <address@hidden> wrote:
>
>>> (...)The only clue I have is
>>> (completly mysterius to me) error message: "We don't support multiple
>>> metadata areas".
>>>
>>
>> Hi,
>>
>> This error come from lvm, perhaps you can try raid10 first.
>>
>>
>
> I played a bit when I had free time and...
>  - I learned to ignore grub error messages :D
>  - RAID10 seems to work OK
>  - LVM @ RAID10 @ single partition (on each disk) results in above error
> message but if I add small partition (so there are 2 partitions per disk)
> there is no error. I tried with different number of LVs, different LV names,
> anything.. could it be some error in grub after all ?
>
>    Anyway even if there is no such error grub doesn't work - it appers that
> core.img doesn't include LVM module (I tried to specify it manually) or just
> doesn't install at all, of course grub-setup return some error (unknown root
> device or something..) but in the other hand I saw the same error with root
> filesystem on RAID device and it actually worked.
>    There is also another problem: when I installed grub on single HD with
> LVM module in core.img, I couldn't see any LVM devices in the system (only
> hdX, mdX..), I saw something similar on some mailing list (debian ?) -
> removing LVM module then inserting it again fixed that problem, however in
> my case it didn't worked.
>    I'm thinking about installing grub by hand, i.e. creating core.img and
> copying it along with boot.img after mbr,  will that work ? (I just want to
> bypass grub-setup).

Hi,

Perhaps you can describe the steps used to create the LVM volume,
along with version number of tools. Let me see if the error can be
recreated in qemu.

>
>>
>> Yes, it should work out of the box, although there is a small catch.
>> If you're using raid5/raid6 and one/two of the disk is missing or
>> corrupted, you need to add module raid5rec/raid6rec using the --module
>> option in grub-install.
>>
>
> Just curiosity - why it's in separate modules ?

It's caused by size limitation of mbr, which is normally 63 sectors.
When you use the following modules:

biosdisk pc reiserfs lvm mdraid raid6 raid6rec

The size of core.img would exceed 63 sectors, so that it can't be
installed to mbr.

-- 
Bean