Friday, May 9, 2008

Device-mapper driver

I want to explain in what state my driver is currently how to test etc.. 

Actually I have implemented 3 simple targets[1] inside NetBSD device-mapper. I can 
create virtual block device based on linear target(in linux LVM it is Logical volume).  
I can create file-system on it and mount it. 

For now I have to use this command to create file-system on my dm device

newfs -F -s {size} /dev/mapper/{char  device}

DIOWEDGEINFO and DIOCGDINFO ioctls are not implemented now and therefore 
newfs can find size of virtual block device. These ioctls are next on my task list.

Other more sophisticated targets like stripe, mirror, snapshot are not implemented but with help of reinoud@ I have added support for them in to C structures.  Structure layout can be found at [2].

Yesterday I have tried lvm2tools with my current driver and they mostly refuse work on NetBSD.  I will look at this next I want to finish this before coding period for SOC project starts. Because in summer I will have no time to work on device-mapper backend I will be busy with rewriting of interface to functional state.

[1]http://people.redhat.com/agk/talks/FOSDEM_2005/
[2]http://147.175.97.81:8080/dm/revision/file/8a70e9e68ab656befa48f3f58b08a6c65f9a2f9e/dm.h

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