need help in installing debian on p21

I searched a lot about installing debian on p21 but everyhwhere found it for pro and v2
Dont know if the pro and p21 have same install procedure :(
Little noob in this
can u pls help me in this
And now I am using arch linux.
So do I have to revert to original first or directly have to install.
Need instructions
Thanks

P21 is usually Oxnas, and has different installation procedure. To make sure that you have Oxnas version look at dmesg output (the first few lines shows the machine type).

If it is V2 then all you need is to either rerun the installation for Debian. If it is Oxnas then see here:
http://forum.doozan.com/read.php?3,6336

Yes it is oxnas
I am using arch linux
And installed with v3 installtion procedure
Arch is giving me a lot of problems. Thats why want to try debian
Can you please tellme the procedure bro :)
Thanks

I did, above.