Re: [gentoo-user] Botched Raid1 install

[Daniel Frey]

On 01/-10/37 11:59, James wrote:
> Background:
> I worked on this last April can gave up on the (livedDVD)
> install with too many other things to do, and pissed off at
> a lack of usable (current) documentation.
>
> So, taking a fresh look at the BOTCHED system:
> The 2 drives are identical 2TB: Seagate
> drives:  Model Number:       ST32000542AS
>
> I read about the 4K block problem and could have
> easily made a formating mistake....(?).
>
> fdisk /dev/sda  (not the best tool to use...
>

fdisk does have a partition/drive limit of ~2.2TB, but this drive should
still work with it. The only other option is GPT, but I don't think grub
boots from that yet (unless you use grub2 with patches?)

>
> Disk /dev/sda: 2000.4 GB, 2000398934016 bytes
> But in my attempt to install, I used this geometry:
> fdisk    -H 224 -S 56 /dev/sda

That should align it to 4k blocks, I had to do the same on my SSD
(224/56=4)...


> using the livedDVD:
>
>  cat /proc/mdstat
> Personalities : [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
> md125 : active raid1 md127p1[0]
>       262080 blocks [2/1] [U_]
>
> md126 : active raid1 md127p2[0]
>       5023680 blocks [2/1] [U_]
>
> md127 : active raid1 sdb[1] sda[0]
>       1948227584 blocks [2/2] [UU]
>
>

Are the partitions on each drive *exactly* the same? If the end cylinder
and start cylinder for the other drive is off by one it will affect two
partitions, leaving them in a dirty state and the third in a clean state.

>
> It has been suggested kernel >=2.6.37 will have (better?)
> support for 4k sectors disks [1].
>

I believe I have 2.6.37 on my htpc and it works fine with the 4k-aligned
SSD.

> Should I just start over?

I would start over.

Are you using BIOS-raid? (Such as Intel ICH*R?) I assume no, given the
'fd' type partitions. If you are, you are using the wrong approach. It's
already in a raid set and you need to create normal partitions on it,
not type 'fd'.

However, there's a lot of information on how to use mdraid and create
native linux software raid partitions.

If you are trying to use BIOS raid, it's a little different, and
unneeded if you are not using Windows. The reason I mention this is that
mdadm gave my BIOS fakeraid /dev/md126* partitions. When I created
native linux raid partitions, they were /dev/md0, /dev/md1, etc.

I can't really help more until I know exactly what you are trying to do.
Right now (to me, anyway) it looks like you are mixing software raid and
BIOS fakeraid, as with native mdadm you generally don't have partitions
(/dev/md126p1, /dev/md126p2, etc) with native raid (which is /dev/md0,
/dev/md1, etc) as I said above.

If you are trying to use mdadm with a BIOS fakeraid, then you are
correct in that there's no documentation. Just yesterday I finally got a
working install after three weeks of messing around.

What's the output of `mdadm --detail-platform`?

Dan