SCSI disk device nodes

Device names for SCSI disks are assigned in the order in which the devices are detected. In a typical SAN environment, this can mean a seemingly arbitrary mapping of names to actual devices that can change between boots. Therefore, using standard device nodes of the form /dev/<device_name> where <device_name> is the device name that the SCSI stack assigns to a device, can be a challenge.

Alternatively, you can use udev to create device nodes that are based on unique properties of a SCSI device and so identify a particular device. Such device nodes are independent of the sequence in which the devices are set online and can help you to reliably address an intended disk space.

Multipath

Users of SCSI-over-Fibre Channel attached devices should always consider setting up and using redundant paths through their Fibre Channel Storage Area Network.

Path redundancy improves the availability of the LUNs. In Linux®, you can set up path redundancy using the device-mapper multipath tool. For information about multipath devices and multipath partitions, see the chapter about multipathing in How to use FC-attached SCSI devices with Linux on z Systems®, SC33-8413.