oracleasm scandisks - Unable to instantiate disk "vol_name"

APPLIES TO:

Linux OS - Version Oracle Linux 5.0 and later
Linux x86
Linux x86-64

SYMPTOMS

System:

# uname -a ; rpm -qa |grep oracleasm
Linux el5pvHAguest 2.6.18-92.1.17.0.1.el5xen #1 SMP Tue Nov 4 16:01:14 EST 2008 i686 i686 i386 GNU/Linux

oracleasmlib-2.0.3-1.el5
oracleasm-2.6.18-92.1.17.0.1.el5xen-2.0.5-1.el5
oracleasm-support-2.1.0-5.el5
#    

Scandisk returns no message:

# /etc/init.d/oracleasm scandisks
Scanning the system for Oracle ASMLib disks: [ OK ]
#

Tailing the /var/log/oracleasm log:

# tail -f /var/log/oracleasm
oracleasm-read-label: Unable to open device "/dev/dm-1": No such file or directory
Reloading disk partitions: done
Cleaning any stale ASM disks...
Scanning system for ASM disks...
Disk "VOLDATA001" does not exist or is not instantiated
Instantiating disk "VOLDATA001"
Unable to instantiate disk "VOLDATA001"

Note with with oracleasm-support 2.1 you can also use the oraclasm binary, from /usr/share/doc/oracleasm-support-2.1.0/ReleaseNotes:

New in 2.1.0
------------
* There is a new '/usr/sbin/oracleasm' command that provides a much more
flexible interface to the oracleasm support software. oracleasm
operations are subcommands for the 'oracleasm' program. The
/etc/init.d/oracleasm script now uses the 'oracleasm' program as well.
All new features are accessed by using the new 'oracleasm' command.

Using the new oracleasm binary you see:

# /usr/sbin/oracleasm scandisks
Reloading disk partitions: done
Cleaning any stale ASM disks...
Scanning system for ASM disks...
Instantiating disk "VOLDATA001"
Unable to instantiate disk "VOLDATA001"
Instantiating disk "VOLDATA001"
Unable to instantiate disk "VOLDATA001"
Instantiating disk "VOLDATA001"
Unable to instantiate disk "VOLDATA001"
#
#
# /usr/sbin/oracleasm listdisks
#

CAUSE

The the driver is not loaded and "/etc/init.d/oracleasm configure" had not been completed.
This was seen when a second system was being configured, but oracleasm was not loaded/configured.

SOLUTION

1. Configure oracleasm which will also load driver , for example:

# /etc/init.d/oracleasm configure
Configuring the Oracle ASM library driver.

This will configure the on-boot properties of the Oracle ASM library
driver.  The following questions will determine whether the driver is
loaded on boot and what permissions it will have.  The current values
will be shown in brackets ('[]').  Hitting <ENTER> without typing an
answer will keep that current value.  Ctrl-C will abort.

Default user to own the driver interface [root]:
Default group to own the driver interface [root]:
Start Oracle ASM library driver on boot (y/n) [y]:
Scan for Oracle ASM disks on boot (y/n) [y]:
Writing Oracle ASM library driver configuration: done
Initializing the Oracle ASMLib driver:                     [  OK  ]
Scanning the system for Oracle ASMLib disks:               [  OK  ]
#
#
# /etc/init.d/oracleasm listdisks
VOLDATA001
#