Creating DAS or SAN Disk Partitions for ASM

Question

Oracle® Database Installation Guide 11g Release 2 (11.2) for Linux (http://docs.oracle.com/cd/E11882_01/install.112/e24321/oraclerestart.htm#CHDBJGEB)
*3.6.3 Step 2:* Creating DAS or SAN Disk Partitions for Oracle Automatic Storage Management
In order to use a DAS or SAN disk in Oracle ASM, the disk must have a partition table. Oracle recommends creating exactly one partition for each disk.
My question: why does Oracle recommend creating exactly one partition for each disk? For a disk to be used on Suse Linux, I normally need to at the least 3 partitions, i.e., boot, swap, and root.
Scott

Answer 1

Please read the entire manual - before starting setup and configuration.
From the very same manual:
Do not specify multiple partitions on a single physical disk as a disk group device.
Oracle ASM expects each disk group device to be on a separate physical disk.So why use partitioning? If you need to subdivide a LUN into smaller LUNs and use these instead of the larger LUN. Reasons could range from LUNs bigger than 2TB in size (ASM only support up to 2TB size LUNs), to wanting partition 1's of x size for ASM diskgroup 1 and partition 2's of y size for ASM diskgroup 2.
If you do partition, take the extra precaution of marking the partition as a non-file system (partition type <i>da</i>) to safeguard against someone (like a sysadmin looking for space) from mounting it as a file system.
Generally though - I would not partition LUNs for ASM use.