How To Identify If A Disk/Partition Is Still Used By ASM, Has Been Used by ASM Or Has Not Been Used by ASM (Unix/Linux)? (Doc ID 603210.1)

In this Document

Goal

Fix

Applies to:

Oracle Server - Enterprise Edition - Version 10.1.0.2 to 11.1.0.7 [Release 10.1 to 11.1]
Information in this document applies to any platform.

Goal

The present 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.

Fix

1) First of all, we need to compile the next C code:

#include
#include
#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   {
    perror(fname);
    return (-1);
  }

  count = read(fd, buf, sizeof(buf));
  if (count   {
    perror(fname);
    return (-1);
  }
  if (count   {
    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 in 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), we can obtain 4 states:

3.1) 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

3.2) 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

3.3) 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

3.4) 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 oracle dba 8, 14 Jun 11 19:12 /dev/sda14