I am assuming you want to do this from Linux and not from CMS. If I remember it right, the DASD driver does not show you the entire device, only the data portion of CKD and also not record 0. This means that if dasd has been once formatted, Linux will try to access it as formatted drive.
There is a way to access raw tracks from Linux, look in Device Drivers, Features and Commands and search for "Accessing full ECKD tracks". Unfortunately, the last time I tried this (a couple of years ago) not all kernels supported this and also even on newer kernels, some non-IBM devices did not support raw track mode from Linux. Why do you need to unformat drives? I once had a similar need because under certain conditions the Linux dasd driver would go into a loop trying to access badly formatted drives (this happened only on certain devices, but I forgot the details). I ended up writing a user exit for the directory manager that would wipe out the first few tracks on a newly created minidisk. HTH, Tomas Tomas Pavelka CA Technologies Sr Software Engineer CA CZ, s.r.o V Parku 12, 148 00 Praha Czech Republic Office: +25996 | tomas.pave...@ca.com Id. Císlo 25694073, z obchodního rejstříku, vedeného Městským soudem v Praze, oddíl C, vložka 61808 / Id. No. 25694073, registered in the Commercial Register maintained by the Municipal Court in Praque, Section C, File 61808 -----Original Message----- From: Linux on 390 Port [mailto:LINUX-390@VM.MARIST.EDU] On Behalf Of Dimitri John Ledkov Sent: Tuesday, May 17, 2016 8:12 AM To: LINUX-390@VM.MARIST.EDU Subject: How to unformat a dasd drive? Hello, Is it possible to "unformat" a dasd drive such that on Linux it appears as "n/f" in lsdasd output? -- Regards, Dimitri. ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit https://urldefense.proofpoint.com/v2/url?u=http-3A__www.marist.edu_htbin_wlvindex-3FLINUX-2D390&d=DQIBaQ&c=_hRq4mqlUmqpqlyQ5hkoDXIVh6I6pxfkkNxQuL0p-Z0&r=DK2K-NIOOl0HxbipU0v85tkUyLDvwTVlpJtE__bnwNo&m=WFNCiVt1kjAqOG9uGgX4U7KnbiL6iFQ2IOERde-8zdU&s=nM3vMo000RB2KxSiVR9roT4FQ_pYUVlbF7-wfXoUEPM&e= ---------------------------------------------------------------------- For more information on Linux on System z, visit https://urldefense.proofpoint.com/v2/url?u=http-3A__wiki.linuxvm.org_&d=DQIBaQ&c=_hRq4mqlUmqpqlyQ5hkoDXIVh6I6pxfkkNxQuL0p-Z0&r=DK2K-NIOOl0HxbipU0v85tkUyLDvwTVlpJtE__bnwNo&m=WFNCiVt1kjAqOG9uGgX4U7KnbiL6iFQ2IOERde-8zdU&s=AbPFiVvF5Taw8nEjIYblCJY-mXyy5EjBLuCZOJ2qyJY&e=
