Re: LSI MegaRAID SAS 9240-4i hangs system at boot
On 6/12/2012 12:05 PM, Ramon Hofer wrote:
> On Sun, 10 Jun 2012 17:30:08 -0500
> Stan Hoeppner <stan@hardwarefreak.com> wrote:
>
> (...)
>
>> You create two 4 drive md RAID5 arrays, one composed of the four
>> identical 1.5TB drives and the other composed of the four identical
>> 2TB drives. Then concatenate the two arrays together into an md
>> --linear array, similar to this:
>>
>> ~$ mdadm -C /dev/md1 -c 128 -n4 -l5 /dev/sd[abcd] <-- 2.0TB drives
>> ~$ mdadm -C /dev/md2 -c 128 -n4 -l5 /dev/sd[efgh] <-- 1.5TB drives
>> ~$ mdadm -C /dev/md0 -n2 -l linear /dev/md[12]
>
> Sorry I have another question to this procedure:
>
> Can I put the raid5 from the old server which was attached over sata
> to the LSI and mdadm will still recognize the disks? Will the disks
> uuids be the same?
Assuming you create it again with the same device order and parameters,
yes, it should work. You _need_ to ask for assistance with this on the
linux-raid list. I've never done it. People there have, and can
explain in much better. It is not a simple process for anyone who has
not done it, and is fraught with pitfalls.
> And when I have added the old raid5 which contains the data can I add
> this to the linear array and still have the data or will it be lost?
No, you cannot add it to the linear array without wiping it first.
Beyond that, if the drive count is not 4, or not RAID level 5, or the
other parameters are different, then you can't use it in the linear
array. As I already mentioned, all the RAID parameters but for disk
size must be the same.
> Hmm, probably I have to create a raid5 with the four empty 2 TB disks
> attached to the LSI. Then:
>
> ~$ mdadm -C /dev/md0 -n1 -l linear /dev/md1
WTF?
> Now I copy the content from the old raid5 with the four 1.5 TB disks to
> the new linear md0.
Shuffleboard... You didn't previously make clear that not all 8 disks
were freely available to build your stack from the ground up. The
instructions I gave you assumed that all 8 drives were clean. Now
you're attempting to modify the precise instructions I gave you and play
shuffleboard with your data and disks, attempting to migrate on the fly.
This may not have a good outcome. I guess you feel that you understand
this stuff and are confident in your ability at this point to effect the
outcome you desire. If things break badly, I'll try to assist, but I
make no promises WRT outcomes nor guarantee my availability.
--
Stan
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