From mboxrd@z Thu Jan 1 00:00:00 1970 From: Moshe Yudkowsky Subject: Unable to eradicate previous version of device information, even with zero-superblock and dd Date: Mon, 28 Jan 2008 09:05:24 -0600 Message-ID: <479DEF34.70306@pobox.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids I've been trying to bring up a RAID10 device, and I'm having some difficulty with automatically-created device names. mdadm version 2.5.6, Debian Etch. With metadata=1.2 in my config file, mdadm --create /dev/md/all --auto=p7 -n 4 --level=10 /dev/sd*2 This does seem to create a RAID array. I see that my /dev/md/ directory is populated with all1 through all7. On reboot, however, I notice that there's a suddenly a /dev/md127 device. Confused, I attempted to start over many times, but I can't seem to create a non-"all" array and I can't seem to create a simple /dev/md/0 array. Steps: To eradicate all prior traces of md configuration, I issue these commands: mdadm --stop /dev/md/all which stops. mdadm --zero-superblock /dev/sd[each drive]2 I went further (after some trouble) and issued dd if=/dev/zero of=/dev/sd[each drive]2 count=2M I then issue: rm /dev/md* /dev/md/* The ARRAY information is commented out of the config file (mdadm.conf). On reboot, I see that the devices /dev/md/all, /dev/md/all1, etc. have reappeared, along /dev/md127, /dev/md_127, and /dev/md_d127. This is very, very puzzling. Well, I thought I could work around this. I issued mdadm --create /dev/md/all with the same paramters as above. I can use cfdisk and fdisk (either one) to create two partitions, /dev/md/all1 and /dev/md/all2. However, mkfs.reiserfs /dev/md/all1 claims that the /dev/md/all1 has "no such device or address." ls -l /dev/md/all gives brw-rw---- 1 root disk 254, 8129 (date) /dev/md/all1 QUESTIONS: 1. If I create a device called /dev/md/all, should I expect that mdadm will create a device called /dev/md/127, and that mdadm --detail --scan will report it as /dev/md127 or something similar? 2. How can I completely eradicate all traces of previous work, given that zero-superblock and dd on the drives that make up the array doesn't seem to erase previous information? -- Moshe Yudkowsky * moshe@pobox.com * www.pobox.com/~moshe "If you're going to shoot, shoot! Don't talk!" -- Eli Wallach,"The Good, the Bad, and the Ugly"