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For this page, we'll assume that we want to use devices /dev/sd[e-z] for ASM.

Identify Disks

Used "fdisk -l | grep Disk" to see that /dev/sd[e-z] are the disks we'll use for ASM (they had no partition table).

Disk Speed Check

for dsk in /dev/sd[e-z]; do echo $dsk; dd if=$dsk of=/dev/null iflag=direct bs=2M count=100; done

Partition Disks

Run this to create disk partitions on partition 4 for ASM use:
for dsk in /dev/sd[e-z]; do echo -en "u n p 4 32768 p w "|fdisk $dsk; done
  • We use partition 4 because it is not typical and will make disks easier to identify for ASM usage later on. There is no technical reason for it.
  • The 32768 offset is for disk alignment. See Christo's blog post, "Aligning ASM Disks on Linux".

udev and Permissions for Disks

IMPORTANT: udev or init configurations need to be in place to ensure that /dev/sd*4 is owned by oracle.

For example, we have these lines in the file /etc/udev/rules.d/99-oracle-asmdevices.rules:
KERNEL=="sd[e-z]4", OWNER="oracle", GROUP="dba", MODE="0660"
Restart the udev service:
# /sbin/udevcontrol reload_rules # RHEL/OEL 4/5
# /sbin/udevadm control --reload-rules # RHEL/OEL 6

# /sbin/start_udev