[dm-devel] 4k block LUN problem

["Vassar, Bob" <Robert Vassar am sony com>]

Hello,

I have a problem with a SAN array. I need LUNs over 2TB (15TB is my target) so my LUN block size is set to 4096. When I remove the black list entry for this device Linux won't boot until the fiber channel lane times out. My SAN appliance is reporting under run errors with a read that is not a multiple of 4096 and debug shows a read of length:0. I think this is coming from the path checker since when I change this to "tur" the system boots and dm sees the equal UUID's and creates the dm-x device.  When I try to create a file system on the dm device this fails writing the super blocks.  

It appears that some dm function can not handle 4096 block size correctly since if I remake my LUN's at 512byte the dm device is created and boots with readsector0 as path checker and I can create an ext file system with no problem.  Does any know if dm only works on 512 block devices or is there a configuration parameter to handle block sizes other than 512 on the physical device (not file system block). I have been back and forth with RH support for over a week and getting very frustrated.  

Thanks,
Bob