[dm-devel] Multipath target does not shift block offset?

[Tim Burgess]

Hi,

I've just been playing with the multipath dm target, and would like to 
create a single device mapper device consisting of several, 
concatenated, multipathed devices.  The intuitive way to do this would be:

# HBA 2 failing to 3
0 286749488 multipath 2 round-robin 1 0 /dev/sdd round-robin 1 0 /dev/sdl
286749488 286749488 multipath 2 round-robin 1 0 /dev/sde round-robin 1 0 
/dev/sdm
573498976 286749488 multipath 2 round-robin 1 0 /dev/sdf round-robin 1 0 
/dev/sdn
<snip>

However, when one tries to set up such a device, we get the error message:

kernel: device-mapper: device /dev/sde too small for target

I would have assumed that the mapping specified above would map the 
whole (sector range 0-286749487) of the sde/sdm device into the range 
286749488-573498975 of the dm device.  However, dm appears to be trying 
to map the range 286749488-573498975 of the dm device to the same 
offsets in the sde/sdm device.

Is this what was intended?

Cheers,
Tim

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