On Mon, Dec 29, 2003 at 06:08:21PM +0100, Christophe Saout wrote:
> 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?

not always (one format has the hd2 offset by 10 sectors)

> 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

thanks for the info! I'll look into what this means ;)