Thank you Andreas for your response. In this case, what is your recommendation, I have a newer OSS hardware that requires >= RHEL 5.8 to support the PERC810 RAID controllers in it which connects to our dumb storage box(OST). Can I downgrade the kernel after the initial install and then reboot with older version or kernel? If I do this my guess is RAID controller wouldn't not work. Any other options here? Thank you, Amit -----Original Message----- From: Dilger, Andreas [mailto:andreas.dilger@intel.com] Sent: Monday, July 01, 2013 10:18 PM To: Kumar, Amit Cc: hpdd-discuss(a)lists.01.org Subject: Re: [HPDD-discuss] Adding new OSS: Kernel & Lustre modules compatibility On 2013-07-01, at 15:55, "Kumar, Amit" <ahkumar@mail.smu.edu<mailto:ahkumar@mail.smu.edu>> wrote: Quick question for Lustre 1.8.5: As we add new OSS, does every OSS need to have the same version of the OS kernel and Lustre modules? Typically yes. This is the only way the code is tested. Cheers, Andreas