Shared Storage Volumes
Shared disks are visible to all nodes in the cluster. Real Application Clusters requires the use of raw devices on Linux or cluster file system files. When using raw devices, carefully partition the disks to insure partitions are sized adequately. The LVM (Logical Volume Manager) is very useful and makes the management of raw devices more flexible.
Use the disk utility from the RedHat system utilities menu to format the disk (there can be multiple partitions or one large partition).
Use pvcreate to create a physical volume for use by the logical volume manager.
$ pvcreate -d /dev/sda
For a single partition on a multi-partition drive, use the partition designator such as /dev/sda1.
Use vgcreate from a root session to create a volume group for the drive or for the partition that will be used for the raw.
$ vgcreate -l 256 -p 256 -s 128k /dev/sda
The above command allows 256 logical partitions and 256 physical partitions with a 128K-extent size.
Use lvcreate to create the logical volumes inside the volume group. An example script is shown below.
pvcreate -d /dev/sda
vgcreate -l 256 -p 256 -s 128k /dev/pv1 /dev/sda
lvcreate -L 500m /dev/pv1
lvcreate -L 500m /dev/pv1
lvcreate -L 300m /dev/pv1
lvcreate -L 100m /dev/pv1
The above commands create /dev/pv1/lvol1 to lvoln.
Next, bind the volumes to the raw devices. This is accomplished through the /usr/bin/raw command.
vgchange -a y /dev/pv1
/usr/bin/raw /dev/raw/raw1 /dev/pv1/lvol1
/usr/bin/raw /dev/raw/raw2 /dev/pv1/lvol2
/usr/bin/raw /dev/raw/raw3 /dev/pv1/lvol3
/usr/bin/raw /dev/raw/raw4 /dev/pv1/lvol4
/usr/bin/raw /dev/raw/raw5 /dev/pv1/lvol5
/usr/bin/raw /dev/raw/raw6 /dev/pv1/lvol6
/usr/bin/raw /dev/raw/raw7 /dev/pv1/lvol7
/usr/bin/raw /dev/raw/raw8 /dev/pv1/lvol8
/usr/bin/raw /dev/raw/raw9 /dev/pv1/lvol9
Soft links can be created from the raw volumes to make file recognition easy.
Using Network Attached Storage (Filers)
Network attached storage can be used for storing the RAC database files in an Oracle RAC on a Linux cluster, besides the usual SCSI and FC-based direct and SAN-based shared storage. However, the support is very limited at this time. Only the Network Appliance Filer (8xx and 9xx Series), EMC Celerra and Fujitsu filers (NR1000 Series) are currently supported for network-attached storage.
We will briefly examine the storage part of the implementation using NetApp filer 880.
Sample storage configuration steps include:
For more details, see the white paper ‘Oracle9i RAC Installation with a Netapp Filer in Red Hat Advanced Server Linux environment’ by Sunil Mahale, Vasu Subbiah, Petros Xides - September 2002
For more information, see the book Oracle 11g Grid and Real Application Clusters 30% off if you buy it directly from Rampant TechPress .
Written by top Oracle experts, this RAC book has a complete online code depot with ready to use RAC scripts.