HP-UX 11i v3 Mass Storage Device Naming

• It enables certain re-configurations of the host system and the storage area network (SAN),
without affecting the representation of the device on the host system. This includes operations
such as connecting the device through a different HBA on the host, and moving the device to
a different switch or hub in the SAN.
Persistent Device Special File (DSF) Naming Scheme
The persistent DSF is a path independent and persistent
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representation of a Logical Unit (LUN). It is
bound to the LUN using the LUN’s unique World Wide Identifier (WWID). If the device is moved the
persistent DSF is not affected.
The format of a persistent DSF name is as follows: /dev/<subdir>/<class><instance>[options]
• subdir: A subdirectory for the device class (for example, rdisk for raw device special files for
disks, disk for block device special files for disks, rtape for raw device special files for tape
devices, etc.).
• class: In general this corresponds to the class of the device: tape, disk, etc.
• instance: instance number assigned by the operating system to the device within its class.
• options: device options depending on the class of the device. For instance disk partition, tape
density selection.
Note: To determine class and instance number of devices, run the ioscan command (see
ioscan(1M)
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).
If the device does not support a LUN WWID (inquiry page 0x83), the system can not uniquely
identify it. In this case the system creates a device special file in the format described above, but the
device special file will be associated with the path through which the device is discovered. If the
device has multiple paths, multiple DSFs will be created. If the device is moved or the SAN is re-
configured, the device special file may change as a unique LUN WWID is not available to fully and
uniquely identify it.
The system automatically creates both legacy and persistent device special files for all devices
discovered on the system
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, and for certain predefined device options depending on the driver the
device is bound to. However, legacy device special files are created only up to the architectural limit
which allows up to 32768 legacy DSFs and 256 ext_bus. Above the legacy addressing scheme
limits, only persistent device special files are created.
The following sections describe the agile addressing naming scheme for different device classes.
Disk device file naming convention
Disk devices correspond to block devices including the following types: random access, storage
array, CD/DVD, Write-Once Read-Multiple (WORM), and Optical Memory (OM). They are typically
claimed by the esdisk class driver. The format of the device special file depends on the method used
to access the device:
• Raw access: /dev/rdisk/disk<instance>[_p<disk_partition_number>]
• Block access: /dev/disk/disk<instance>[_p<disk_partitionnumber>]
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Persistency only applies to the current installation and may not be maintained across re-installations
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On 11i v3 the default view of ioscan is the legacy view, to see new agile information with ioscan use the ‘–N’ option.
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Legacy devices are not created when legacy mode has been disabled with the rmsf –L command.
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