port-amd64/43105: Destroying a GPT partition with dd will cause gpt destroy / create to fail

[peter%kerwien.homeip.net@localhost]

>Number:         43105
>Category:       port-amd64
>Synopsis:       Destroying a GPT partition with dd will cause gpt destroy / 
>create to fail
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    port-amd64-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Apr 02 11:55:00 +0000 2010
>Originator:     Peter Kerwien
>Release:        NetBSD 5.0.2_PATCH
>Organization:
>Environment:
NetBSD server1 5.0.2_PATCH NetBSD 5.0.2_PATCH (GENERIC) #0: Sat Mar 27 17:55:16 
UTC 2010 root@server1:/usr/obj/sys/arch/amd64/compile/GENERIC amd64
>Description:
When I created a large disk array, and tried to add a gpt partition it failed 
to destroy/create a GPT label:

server1# gpt -v destroy sd0
gpt: rsd0d: mediasize=4499999293440; sectorsize=512; blocks=8789061120
gpt: unable to open device 'rsd0d': Invalid argument

The reason for this (According to Christos Zoulas, thx for all help!) is that I 
destroyed a GPT partition with dd, the trailing GPT copy will not be able to 
get validated leading to inability to remove/add a new GPT label.

I had to zap it with the help of some small program:

#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <err.h>

int
main(void)
{
        static char buf[0x200];
        int fd = open("/dev/rsd0d", O_RDWR);

        if (fd == -1)
                err(1, "open");
        if (lseek(fd, 0x417bcdbfe00ULL, SEEK_SET) == (off_t)-1)
                err(1, "lseek");
        if (write(fd, buf, sizeof(buf)) == -1)
                err(1, "write");
        (void)close(fd);
        return 0;
}

Then I managed to execute gpt destroy / created on sd0 to create a new GPT 
partition again.

For more information, see the following thread:

http://mail-index.netbsd.org/netbsd-users/2010/03/30/msg005937.html
>How-To-Repeat:
1. Destroy a GPT partition with dd.
2. Try to destroy / create a new label with:

# gpt destroy sd0

or

# gpt create sd0. Will result in:

gpt: unable to open device 'rsd0d': Invalid argument

>Fix:
Zap the trailing EFI partition at the end of the disk.