On 11/26/13 04:29, Luca Ferrari wrote: > On Tue, Nov 26, 2013 at 9:49 AM, obsd, cgi <obsd...@postafiok.hu> wrote: >> Wouldn't it be much easier that before I create the bioctl softraid CRYPTO >> I would dd zero the psychical disk for the first.. dunno, 10 MBytes? > > I don't see how and why it should be easier. We are talking about a > single line dd command with a different target and count, isn't it? > > Luca
not only that, zeroing the physical disk doesn't resolve the problem you may run into. People tend to be creatures of habit. Given no reason to do otherwise, people tend to do the same thing over and over. So...today, you take a couple disks, zero the first 10MB, put a 1G boot partition and make the rest RAID, then build a mirrored set, do your testing, and call it done. Tomorrow, you take the same disk, zero the first 10MB, put a 1GB boot partition on it, and make the rest RAID, and intend to build a crypto RAID partition on it. Except...Poof! your RAID1 chunk is baaack! Why? Because you didn't touch the softraid data which is 1GB up the disk. Done this a few times. :-/ Just zero the RAID partition. Then, especially in the case of crypto, zero the RAID disk, too. (yeah, I just slightly changed my advice. Thinking about it further, fdisk and disklabel sometimes have got really confused by things that don't look right. I think things have been improving there, but I'm not sure all edge cases have been fixed. If you zero the RAID partition BEFORE creating a RAID1, odds are what is there will look like a lot of zeros. Crypto...almost certainly it WON'T look like a lot of zeros, and it might be useful to put it to a lot of zeros first. So, zeroing the partitions then zeroing the softraid "disk" is the safest and easiest. Can you skip one? Maybe. If it fails, trust me, you will lose all the time you think you saved, many times over) Nick.
