On 15.11.2010 13:27, Zoltan Szecsei wrote:
On 2010-11-14 18:48, Mikael Abrahamsson wrote:
*What is the correct fdisk or parted method get rid of the DOS & GPT
flags, and create a correctly aligned partition, and should this be a
0xda partiton (& then I use metatdata 1.2 for mdadm)?
I just "dd if=/dev/zero of=/dev/sdX bs=1024000 count=1" to zero the
first megabyte of the drive to get rid of the partition table (you get
rid of the v1.2 metadata at the same time actually). Then you know for
sure you're correctly aligned as well as md is 4k aligned.
I did this on all 8 drives (/dev/sd[a-h])
root@gs0:/etc# dd if=/dev/zero of=/dev/sdb bs=1024000 count=1
1+0 records in
1+0 records out
1024000 bytes (1.0 MB) copied, 0.0103209 s, 99.2 MB/s
root@gs0:/etc# dd if=/dev/zero of=/dev/sdc bs=1024000 count=1
But the GPT id has not disappeared.
You might want to do blockdev --rereadpt /dev/sd[a-h] to make sure
kernel registers new situation (or do the same with sfdisk -R)
Also, GPT stores backup partition table + gpt header at the end of the
disk. Kernel might be clever enough to rely on it if you destroy the
data at the beginning of the disk.
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