The below small C program will help us to identify if a Disk/Partition is still used by ASM, has been used by ASM or has not been used by ASM on Unix or Linux platforms.
1. First of all, we need to compile the below C code:
#include <stdio.h>
#include <fcntl.h>
#define BLOCK_SIZE 4096
int main(int argc, char *argv[])
{
char buf[BLOCK_SIZE];
char *fname;
int fd;
int count;
if (argc != 2)
{
fprintf(stderr, "Exactly one argument required\n");
return (-1);
}
fname = argv[1];
fd = open(fname, O_RDONLY);
if (fd < 0)
{
perror(fname);
return (-1);
}
count = read(fd, buf, sizeof(buf));
if (count < 0)
{
perror(fname);
return (-1);
}
if (count < sizeof(buf))
{
return (1);
}
if ( buf[32] == 'O' && buf[33] == 'R' && buf[34] == 'C' && buf[35] == 'L'
&& buf[36] == 'D' && buf[37] == 'I' && buf[38] == 'S' && buf[39] == 'K')
{
if (buf[71] != 4) {
printf("This disk %s still used by ASM\n",argv[1]);
return (0);
}
else
printf("This disk %s has been used by ASM\n",argv[1]);
return (0);
}
printf("This disk %s has not been used by ASM\n",argv[1]);
return (1);
}
2. Save the above code as an ASCII file, then using a C Compiler compile it as follow:
$ ls -rw-r--r-- 1 oracle oinstall 2014 Jun 16 15:57 checkasmdisk.c
$ cc checkasmdisk.c -o checkasmdisk
$ ls -rwxr-xr-x 1 oracle oinstall 5670 Jun 16 15:57 checkasmdisk -rw-r--r-- 1 oracle oinstall 2014 Jun 16 15:57 checkasmdisk.c
3. Check the desired disk(s) with the compiled script. we can obtain 4 states as shown below as a result of the script:
1. Disk has not been used by ASM
Connected to: Oracle Database 11g Enterprise Edition Release 11.1.0.6.0 - Production With the Partitioning, OLAP, Data Mining and Real Application Testing options SQL> !dd if=/dev/zero of=/dev/sda14 bs=8192 count=12800 12800+0 records in 12800+0 records out SQL> !checkasmdisk /dev/sda14 This disk /dev/sda14 has not been used by ASM
2. Disk is still used by ASM
SQL> create diskgroup DATADG external redundancy disk '/dev/sda14'; Diskgroup created. SQL> !checkasmdisk /dev/sda14 This disk /dev/sda14 still used by ASM
3. Disk has been used by ASM
SQL> drop diskgroup DATADG; Diskgroup dropped. SQL> !checkasmdisk /dev/sda14 This disk /dev/sda14 has been used by ASM
4. Disk cannot be accessed
# ls -l /dev/sda14 brw-rw---- 1 oracle dba 8, 14 Jun 11 19:12 /dev/sda14 # chown root:disk /dev/sda14 # ls -l /dev/sda14 brw-rw---- 1 root disk 8, 14 Jun 11 19:12 /dev/sda14 SQL> !checkasmdisk /dev/sda14 /dev/sda14: Permission denied brw-rw---- 1 root disk 8, 14 Jun 11 19:12 /dev/sda14