Re: ataraid in 2.6.?

[Christophe Saout <christophe@saout.de>]

Am Mo, den 29.12.2003 schrieb Arjan van de Ven um 10:49:
>
> the plan is to have a userspace device mapper app take it's place.
> As for the timeframe; I'm looking at it but the userspace device mapper
> code is still a bit of a mystory to me right now.

It is? I think it's kind of simple (probably, if you know what's going
on ;)). Which interface are you looking it?

I'm just looking at the ataraid code. Is my assumption correct, that it
simply interleaves sectors between two harddisks? Even sector number ->
hd1, odd number -> hd2?

Using the simple dmsetup tool one could try something like:

echo 0 $(expr $(blockdev --getsize /dev/<HD1>) \* 2) stripe 2 1
/dev/<HD1> 0 /dev/<HD2> 0 | dmsetup create ataraid

Where <HD1> and <HD2> should of course be replaced by the raw disks.

If everything is correct a device /dev/mapper/ataraid should be created.

Using libdevmapper something like:
dm_task_create(DM_DEVICE_CREATE)
dm_task_task_set_name (required)
dm_task_set_uuid (optional)
dm_task_add_target (only once in this case, contains the stripe target)
dm_task_set_ro (if readonly)
dm_task_set_major / _minor (if you don't want a dynamically allocated)
dm_task_run

--
Christophe Saout <christophe@saout.de>
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