Enabling device persistence for newly discovered LUNs

The Linux Host sees LUNs on the storage system as SCSI devices. When you have multiple LUNs, you must be able to persistently identify each LUN across system reboots. This means you should make sure each LUN has a unique file system label and then mount the file system using that label.

Before you begin

Discover the LUNs.

About this task

The issue of persistent identification occurs because the Linux operating system assigns a unique device name, such as /dev/sda, to each LUN as it discovers the LUN. If you reboot or restart the iSCSI service, these names might change because the order in which the operating system discovers LUNs cannot be predicted.

When you use multipathing, DM-Multipath automatically creates persistent devices for each LUN in the /dev/mapper/ directory on the Linux host.

Step

Mount the new file system by adding an entry to /etc/fstab.

If you are running ...	Enter the following line ...
DM-Multipath with Red Hat Enterprise Linux	`device mount_point type` _netdev,defaults 0 0
DM-Multipath with SUSE Linux Enterprise Server	`device mount_point type` _netdev,defaults nofail,rw 0 0

device is the name of the device in the /dev/mapper/ directory. You can create a file system directly on a multipath device in /dev/mapper/. You do not have to create a partition or label on the multipath device.

mount_point is the mount point you created for the file system.

type is the file system type, such as ext2 or ext3.

_netdev is used for any network-dependent devices such as iSCSI. It is only used in iSCSI environments and lets you add iSCSI mount point devices to /etc/fstab.