NetBSD LVM SoC project

[Adam Hamsik <haaaad%gmail.com@localhost>]

Hi, folks

We (I and martin@) are working on NetBSD LVM support. Basically it is  
device-mapper driver written
from scratch. We decided to go this way because it seems to be easiest  
way to get LVM functionality to NetBSD. Also Linux lvm2tools and  
libdevmapper are well tested and they are use in production.

1)
Linux LVM has 3 parts: device-mapper driver, libdevmapper library and  
lvm2tools.

Device-mapper driver maps logical blocks to physical blocks with  
predefined strategy called "target". Communication protocol between  
libdevmapper and device-mapper is defined as number of ioctl calls.

LVM2 tools do most of magic what is needed to get LVM properly done.  
lvm2tools create physical volumes, volume groups and logical  
volumes(logical disks). Only Logical volumes go through
device-mapper driver.

2) Actual device-mapper driver status

We have implemented ioctl interface with some minor cases which are  
not needed now. We have working zero and error targets(they are only  
made for testing;). We are looking to get linear target done
before SoC application starts.

3) SoC tasks

Want to do

3.1) import device-mapper, lvm2tools into NetBSD base system. Get  
lvm2tools into useable state.
   LVM2tools are ported but doesn't work now.

3.2) change standard ioctl interface to use proplib in our tree. I  
think this is way to go because
   actual ioctl interface is really messy. In this task I have to  
change 2 files in libdevmapper
   dmsetup/dmsetup.c and lib/ioctl/libdm-iface.c and our device- 
mapper driver.

3.3) Improve and test our device-mapper code. Probably with ATF test  
suite.

3.4) Write documentation and import it into htdocs.

 If time permits tasks

3.1) multipath target used for mutlipathing devices.

3.2) clustered LVM.

My time plan is this

In first part of SoC timeframe work on LVM2tools integration and  
device-mapper bug fixes.

After first Mid-term evaluations deadline I want to work on proplib  
interface and get it done.

In August 18 I want to start with writing documentation and if time  
permits I want to look at clusterlvm.

I'm attaching more detailed file to this mail.

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Description: Adobe PDF document

Regards

Adam.

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