Veritas Volume Manager 5.0.1 Administrator's Guide, HP-UX 11i v3, First Edition, November 2009

Discovering disks and dynamically adding disk arrays
DMP uses array support libraries (ASLs) to provide array-specific support for
multipathing. An array support library (ASL) is a dynamically loadable shared
library (plug-in for DDL). The ASL implements hardware-specific logic to discover
device attributes during device discovery. DMP provides the device discovery
layer (DDL) to determine which ASLs should be associated to each disk array
In some cases, DMP can also provide basic multipathing and failover functionality
by treating LUNs as disks (JBODs).
How DMP claims devices
For fully optimized support of any array and for support of more complicated
array types, DMP requires the use of array-specific array support libraries (ASLs),
possibly coupled with array policy modules (APMs). ASLs and APMs effectively
are array-specific plugins that allow close tie-in of DMP with any specific array
model.
See the Hardware Compatibility List for the complete list of supported arrays.
During device discovery, the DDL checks the installed ASL for each device to find
which ASL claims the device. If no ASL is found to claim the device, the DDL checks
for a corresponding JBOD definition. You can add JBOD definitions for unsupported
arrays to enable DMP to provide multipathing for the array. If a JBOD definition
is found, the DDL claims the devices in the DISKS category, which adds the LUNs
to the list of JBOD (physical disk) devices used by DMP. If the JBOD definition
includes a cabinet number, DDL uses the cabinet number to group the LUNs into
enclosures.
See “Adding unsupported disk arrays to the DISKS category” on page 92.
DMP can provide basic multipathing to ALUA-compliant arrays even if there is
no ASL or JBOD definition. DDL claims the LUNs as part of the aluadisk enclosure.
The array type is shown as ALUA. Adding a JBOD definition also enables you to
group the LUNs into enclosures.
Disk categories
Disk arrays that have been certified for use with Veritas Volume Manager are
supported by an array support library (ASL), and are categorized by the vendor
ID string that is returned by the disks (for example, “HITACHI”).
Disks in JBODs which are capable of being multipathed by DMP, are placed in the
DISKS category. Disks in unsupported arrays can also be placed in the DISKS
category.
See “Adding unsupported disk arrays to the DISKS category” on page 92.
83Administering disks
Discovering and configuring newly added disk devices