Installation guide

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Once PowerPath software is configured, new logical disk devices of the form
/dev/emcpowera are added to the end of the list. These logical devices correspond one-
to-one to the actual physical LUNs. Do not be alarmed if the emcpower logical devices
do not show up immediately after installing PowerPath. Often, you have to reboot each
server to see the logical disk devices. To confirm the mapping of /dev/sda physical
devices to /dev/emcpowera logical devices, issue the following command as the root
user:
# powermt display dev=all
At this point, it is necessary to create at least one OS partition on each of the LUNs. The
command to create partitions is “fdisk”. A typical session with fdisk to create a single
partition on a LUN would proceed like the following:
# fdisk /dev/emcpowera
p (to create a primary partition)
1 (to create partition 1)
<return> (to accept the first block as the start of the partition)
<return> (to accept the final block as the end of the partition)
w (to write the partition header to the disk)
Following the creation of partitions, the disks need to be formatted with file systems (or
the equivalent). Oracle is actually rather flexible, allowing disks to be formatted with
standard Linux file systems, the Oracle Cluster File System, Oracle Automatic Storage
Management Disk Group format, or simply left as raw disk devices. The last four
options are most appropriate for working with Oracle Real Application Cluster databases
(configuring Oracle RAC is beyond the scope of this whitepaper). It is usually most
appropriate to configure external storage designated for OracleAS servers with a Linux
file system. The following command formats a partition as a Linux ext3 file system with
a large number of potential files and a label to mount the file system with:
# mke2fs –j –N 5000000 –L /myfilesystem /dev/emcpowera1
Create a mount point for the file system by creating an empty directory with the
command:
# mkdir /myfilesystem
To mount the file system at boot time, place a line in the /etc/fstab file with syntax similar
to the following:
LABEL=/myfilesystem /myfilesystem ext3 defaults 0 0
To test the mount immediately, issue the command:
# mount –t ext3 /dev/emcpowera1 /myfilesystem
Use the following commands to confirm the file systems:
# mount
# df –h
The SAN should now be configured to work with OracleAS.