Device Emulation Types; Partitions; Failover - HP XP20000/XP24000 Configuration Manual

• Multimode optical cables with SC or LC connectors
• Public or private arbitrated loop (FC-AL) or direct fabric attach
• Fibre Channel switches
Even though the interface is Fibre Channel, this guide uses the term "SCSI disk" because disk array
devices are defined to the host as SCSI disks.

Device emulation types

The XP family of disk arrays and the SVS 200 support these device emulation types:
OPEN-x devices: OPEN-x logical units represent disk devices. Except for OPEN-V, these devices
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are based on fixed sizes. OPEN-V is a user-defined size based on a CVS device. Supported
emulations include OPEN-3, OPEN-8, OPEN-9, OPEN-E, OPEN-L, and OPEN-V devices.
LUSE devices (OPEN-x*n): Logical Unit Size Expansion (LUSE) devices combine 2 to 36 OPEN-x
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devices to create expanded LDEVs larger than standard OPEN-x disk devices. For example, an
OPEN-x LUSE volume created from ten OPEN-x volumes is designated as OPEN-x*10.
• CVS devices (OPEN-x CVS): Volume Size Configuration (VSC) defines custom volumes (CVS) that
are smaller than normal fixed-sized logical disk devices (volumes). OPEN-V is a CVS-based custom
disk size that you determine. OPEN-L does not support CVS. Although OPEN-V is a CVS-based
device, the product name in the SCSI inquiry string is OPEN-V opposed to the fixed size
OPEN-[389E] devices that appear as OPEN-x-CVS.
LUSE (expanded) CVS devices (OPEN-x*n CVS): LUSE CVS combines CVS devices to create an
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expanded device. This is done by first creating CVS custom-sized devices and then using LUSE to
combine from 2 to 36 CVS devices. For example, if three OPEN-9 CVS volumes are combined to
create an expanded device, this device is designated as OPEN-9*3-CVS. OPEN-V devices are
designated as OPEN-V*n (without CVS).
NOTE:
For the SVS 200, and the XP24000/XP20000/XP12000/XP10000 when connected to external storage
devices, HP recommends using OPEN-V as the emulation the array makes visible to the host. This allows
configuration of external storage LDEVs without losing data. Using any other emulation may cause data
loss in the external storage LUNs. For new deployments, OPEN-V should be chosen because some features
(such as XP Snapshot or Continuous Access Journal) are only supported with OPEN-V.
Refer to Table 8

Partitions

In a Linux environment, one LUN can be divided into a maximum of four primary partitions (using
fdisk) or maximum of one extended partition.

Failover

The disk arrays support many standard software products that provide host, application, or I/O path
failover and management.
12 Installing and configuring Linux for the XP disk array
on page 30 for detailed information.