Architecture considerations and best practices for architecting an Oracle RAC solution with Serviceguard and SGeRAC

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Cluster-wide Device Special Files
Using Cluster-wide Device Special Files (cDSF) provides additional clarity and simplicity when
planning and implementing an LVM storage configuration on HP-UX. Cluster-wide Device Files,
available starting with Serviceguard A.11.20, ensure that each storage device used by a cluster has
a unique device file name across all nodes. For more information, see
Managing Serviceguard
eighteenth edition.
ASM over SLVM
Starting with SGeRAC A.11.17, ASM over SLVM is also available as another storage option for RAC.
The advantages of using SLVM as an underlying volume manager for ASM are:
• An ASM with SLVM configuration provides multi-pathing for ASM disk groups by using LVM PV
links.
• ASM with SLVM enables the HP-UX devices used for disk group members to have the same names
on all nodes easing ASM configuration.
• Protects ASM data against inadvertent overwrites from nodes inside or outside the cluster. If the
ASM disk group members are raw disks, there is no protection from them being incorporated into
LVM volume groups or VxVM disk groups.
Beginning with HP-UX 11i v3 and Serviceguard/SGeRAC A.11.17.01, ASM deployment over raw
disks is supported.
Criteria for choosing the right storage management for RAC
There are always pros and cons with each storage management option. The following list provides
some criteria one should consider when making a decision:
• Ease of administration and management
– File system (CFS is the best option)
– Consistent storage management for all components
• Initial and latent costs of software licenses
– SLVM/CVM raw volumes and ASM are the least expensive
• Desired performance and availability of the solution
– Raw volumes provide the best performance
• Hardware configurations
• Compatibility with existing applications